Lunging Into Stride Length Wrap up!

Here’s our latest in the Sports Health section from Dr. Jonathan Hartman and Dr. Marshall LeMoine. This topic has been broken out into 3 parts due to its’ length so keep an eye out every Wednesday of this month to stay on top of this great article.

We hope you’ve enjoyed this article thus far! To recap here are the links in case you missed them and need a refresher

• Lunging Into Stride Length Part I:  Introducing the Benefits of a Functional Lunge

• Lunging Into Stride Length Part II:  Research Based Evidence of Benefits of the Lunge for Strength and Sport Adaptations

• Lunging Into Stride Length Part III:  Lift Progressions of the Lunge to Optimize Performance

For your reference during the movement assessment, here’s the Step Back Barbell Lunge Movement Fault Guide and quick reference cheat sheet. If you’d like to read on further, the research and citations are listed below!

Here’s the Step Back Lunge demonstrated by Dr Hartman himself. (In case you missed this in our first post.)

Step Back Barbell Lunge Movement Fault Guide:

Lateral View:

• Chin neck angle constant 60-90 (Cue: Hold a tennis ball under chin- DNF, Stick on back/ head, allow gaze to follow body)

• External auditory meatus over shoulder

• Thumbs always over the bar (To avoid wrist extension and wrist injury, also allows for elbows up for latissimus engagement)

• Any bar lunge, the bar will ALWAYS be just below C7 spinous process

• Elbows back and slightly up (should only see one elbow from the side if they are in line)

• Abdominal Brace (Breath in and out at the top of lunge, never bottom position, no trunk rotation or lateral flexion)

• Lumbar spine neutral to start

• Start the lunge with a hip hinge first then allow a knee break and continue with 1:1 knee and hip flexion rate

• Front knee pulled out over toes 1-3 (throughout closed chain knee flexion of the front leg)

• No femoral adduction/IR on either leg when in closed chain (on descend or ascend)

• Front foot does not have excessive pronation

• Both feet start hip distance apart or slightly narrower, foot that steps back tracks in a straight line and lands on the ground in the same plane as starting foot position

• Step back and lower (do not touch knee to ground)

• Re-rack weight by returning to starting position, Look to see that the bar is at the same height on both sides, Lock bar in, then finally Look to check that it is fully locked in, then step out (Always re-rack weight with 3 “L” Check Procedure Look/Lock/Look then step out)

Posterior View:

• Cervical neutral without lateral flexion

• Thumbs always over the bar (To avoid wrist extension and wrist injury, also allows for elbows up for lats engagement)

• Any bar back lunge, the bar will ALWAYS be below C7 spinous process

• Elbows back, slightly up, same height (Bar parallel to ground)

• Abdominal Brace (Breath in and out at the top of lunge, never bottom position, no trunk rotation or lateral flexion)

• Lumbar spine neutral to start

• Start the lunge with a hip hinge first then allow a knee break and continue with 1:1 knee and hip flexion rate

• Front foot neutral eversion / inversion (Toe sign)

• Front knee pulled out over toes 1-3 (throughout closed chain knee flexion of the front leg)

• No femoral adduction/IR on either leg when in closed chain (on descend or ascend)

• Front foot does not have excessive pronation

• Both feet start hip distance apart or slightly narrower, foot that steps back tracks in a straight line and lands on the ground in the same plane as starting foot position

• Equal leg window always seen from posterior view throughout motion

• Step back and lower (do not touch knee to ground)

• Re-rack weight by returning to starting position, Look to see that the bar is at the same height on both sides, Lock bar in, then finally Look to check that it is fully locked in, then step out (Always re-rack weight with 3 “L” Check Procedure Look/Lock/Look then step out)

Quick Look Movement:

• Bar starts on the rack level of inferior scapular angle

• Patient steps under and positions bar, patient feels comfortable with bar weight and is ready

• Set up Trunk to Floor positioning

• Chin neck angle 60-90 entire time without lateral flexion

• Turn on Brace (Tactile cue/one long controlled pursed lip exhale breath or breath held for entire motion is OK)

• One leg steps back and hip hinge initiation with trunk anterior lean to start movement followed by knee flexion

• After hip hinge initiation, hip and knee flexion at same rate on front leg

• Step back and lower (do not touch knee to ground)

• Step back with foot landing in line with starting position

• Avoid Femoral adduction/ IR

• Breath at top and reposition as needed

• Re-rack weight with 3 “L” Check Procedure Look/Lock/Look then step out

Research Quick Reference:

• Gluteus maximus and medius are better activated with exercises that have a single stance leg component (1)

• To Increase the hip extensor impulse and hip extensor EMG of the (G-max and BF) use a forwards trunk lean (Average of 107.9° hip flexion) (7)

• In order to enhance activation of the superficial core musculature unilateral UE weights should be used over bilateral UE weights (14)

• Joint loading progression for the hip can begin with Single-leg squat → Reverse lunge → Forward lunge (3)

• Joint loading progression for the knee and ankle can begin with Reverse lunge → Forward lunge → Single-leg squat (3)

• Walking lunge + weight held in the contralateral arm to the anterior/ moving leg leads to an increase the gluteus medius and vastus lateralis activation. (16)

CITATIONS

1. Boren K, Conrey C, Le Coguic J, Paprocki L, Voight M, Robinson TK. Electromyographic analysis of gluteus medius and gluteus maximus during rehabilitation exercise. International Journal of Sports Physical Therapy. 2011;6(3):206-223.

2. Chowdhury, S., & Kumar, N. (2013). Estimation of forces and moments of lower limb joints from kinematics data and inertial properties of the body by using inverse dynamics technique. Journal of Rehabilitation Robotics, 1(2), 93-98

3. Comfort P, Jones PA, Smith LC, Herrington L. Joint Kinetics and Kinematics During Common Lower Limb Rehabilitation Exercises. Journal of Athletic Training. 2015;50(10):1011-1018. doi:10.4085/1062-6050-50.9.05.

4. Contreras, Bret. Force Vector Training (FVT). The Glute Guy, 1 July 2010, Bretcontreras.com/load-vector-training-lvt/.

5. Dwyer MK, Boudreau SN, Mattacola CG, Uhl TL, Latterman C. Comparision of lower extremity kinematics and hip muscle activation during rehabilitation tasks between sexes. J Athl Train. 2010;45(2):181–190

6. Ekstrom RA, Donatelli RA, Carp KC. Electromyographic analysis of core trunk, hip, and thigh muscles during 9 rehabilitation exercises. J Orthop Sports Phys Ther. 2007;37(12):754–762.

7. Farrokhi S, Pollard CD, Souza RB, Chen YJ, Reischl S, Powers CM. Trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. J Orthop Sports Phys Ther. 2008 Jul;38(7):403-9. doi: 10.2519/jospt.2008.2634. Epub 2008 Apr 15.

8. Flanagan et al (2003). Lower extremity biomechanics during forward and lateral stepping activities in older adults. Clinical Biomechanics, 18(3), 2 14-22. Roger W. Earle (2005). Essential of personal training. National Strength and Conditioning Association.

9. Hefzy MS, al Khazim M, Harrison L. Co-activation of the hamstrings and quadriceps during the lunge exercise. Biomed Sci Instrum. 1997;33:360–365.

10. Khaiyat OA, Norris J. Electromyographic activity of selected trunk, core, and thigh muscles in commonly used exercises for ACL rehabilitation. Journal of Physical Therapy Science. 2018;30(4):642-648. doi:10.1589/jpts.30.642.

11. N Boudreau, Samantha & Dwyer, Maureen & Mattacola, Carl & Lattermann, Christian & Uhl, Tim & Medina McKeon, Jennifer. (2009). Hip-Muscle Activation During the Lunge, Single-Leg Squat, and Step-Up-and-Over Exercises. Journal of sport rehabilitation. 18. 91-103. 10.1123/jsr.18.1.91.

12. Riemann BL, Lapinski S, Smith L, Davies G. Biomechanical Analysis of the Anterior Lunge During 4 External-Load Conditions. Journal of Athletic Training. 2012;47(4):372-378.

13. Riemann, Bryan & Congleton, A & Ward, R & Davies, George. (2013). Biomechanical comparison of forward and lateral lunges at varying step lengths. The Journal of sports medicine and physical fitness. 53. 130-8.

14. Saeterbakken AH, Fimland MS, Navarsete J, Kroken T, van den Tillaar R (2015) Muscle Activity, and the Association between Core Strength, Core Endurance and Core Stability. J Nov Physiother Phys Rehabil 2(2): 028-034. DOI: 10.17352/2455-5487.000022

15. Saeterbakken, Atle & Fimland, Marius. (2011). Muscle activity of the core during bilateral, unilateral, seated and standing resistance exercise. European journal of applied physiology. 112. 1671-8. 10.1007/s00421-011-2141-7.

16. Stastny et al (2015). Does the dumbbell-carrying position change the muscle activity in split squats and walking lunges? Journal of Strength and Conditioning Research, 29(11), 3177-3187. Thomas R. Baechle et al (2013) Essentials of strength training and conditioning. National Strength and Conditioning Association.

17. Stuart MJ, Meglan DA, Lutz GE, Growney ES, An KN. Comparison of intersegmental tibiofemoral joint forces and muscle activity during various closed kinetic chain exercises. Am J Sports Med. 1996; 24(6):792–799.
    

Lunging Into Stride Length Part II: Research Based Evidence of Benefits of the Lunge for Strength and Sport Adaptations

Here’s our latest in the Sports Health section from Dr. Jonathan Hartman and Dr. Marshall LeMoine. This topic has been broken out into 4 parts due to its’ length so keep an eye out every Wednesday of this month to stay on top of this great article.

If you missed last week’s blog post on the Lunging Into Stride Length Part I:  Introducing the Benefits of a Functional Lunge.

Evidence

This next section is split into 3 parts in order to focus on current evidence surrounding muscle activation, the benefits of single leg stance and core activation, and finally how differing variations of the lunge exercise stack up to each other. Let’s start with a 2011 study that utilized EMG to measure the muscle activity of the gluteus maximus and medius of 26 healthy subjects during 18 different lower extremity exercises. This study showed that of the top 4 exercises for gluteal muscle activity the only stance exercise that proved to be of high-level activation was a single leg stance exercise. This study helps to support the idea that exercises incorporating a single leg stance component, such as the movements seen in the ascent and descent of a step lunge will increase the activation of the gluteus maximus and medius muscles (1).

In 2008, Farrokhi et al. performed a study on 10 healthy individuals to determine how a change in trunk position via a forwards lean, neutral, or erect trunk would influence the lower extremity kinematics and kinetics at the hip, knee, and ankle during a forward lunge. This study also monitored how these trunk variations would influence the muscle activity of the lateral gastrocnemius, vastus lateralis, gluteus maximus and biceps femoris. This study showed that the forward trunk lean lunge resulted in an average of 107.9 degrees of hip flexion, and was found to significantly increase the hip extensor impulse and EMG of the gluteus maximus and biceps femoris when compared to the neutral trunk position. This study can further guide our exercise precision and prescription to target the posterior chain via optimizing the trunk angle of the athlete when performing a lung exercises (7).

Forward Trunk Lean Vs. Erect Trunk Lean

In a 2009 study that took 44 healthy individuals, and had them perform a lunge, single-leg squat, and step-up-and-over exercise, and  recorded EMG of 5 muscles (rectus femoris, dominant and nondominant gluteus medius, adductor longus, and gluteus maximus). This study showed that the rectus femoris, gluteus maximus, and dominant side gluteus medius were activated in a progression from least to greatest during the step up and over, lunge, and single leg squat. Interestingly gluteus medius on the non-dominant leg activation was from least to greatest during the single leg squat, step up and over, and then the lunge. This study supports the idea that the lunge muscle activation differs with the dominant and nondominant leg but in either circumstance this exercise is a viable and possible superior choice option for strength training when compared to the step up and over and the single leg squat (11).

Next, surface EMG was used on twelve active female subjects to compare activation of eight trunk, hip/core, and lower limb muscles (erector spinae, rectus abdominis, gluteus maximus, vastus lateralis, rectus femoris, vastus medialis, biceps femoris, and semitendinosus) during the forward lunge, double leg raise, glute bridge, sit-up, and squat. The neutral trunk forward lunge produced significantly higher activation in the vastus medialis, vastus lateralis, and rectus femoris muscles compared to the other exercises, thus supporting the specificity of muscular adaptations to specific lifts (10).

One important take away from these studies is the fact that we can strengthen the lower extremities and gain muscle activation with a majority of the weight emphasis on a single leg. Since we are strengthening with a bias towards one leg the load on the bar or weight held in the hand will be less than a similar closed chain bilateral lower extremity exercise such as the squat. This is a very useful thought as limiting the load on the spine and increasing single leg stability and strength, while activating frontal plane trunk stability may be beneficial for a high level athlete looking for career longevity or for an athlete trying to gain lower extremity strength after recovering from a trunk injury. Not only does this reduce joint forces on the spine, it allows for better matching to sports specific positional movements.

Next, let’s look at the core muscles with lunge progressions. Weights can be held overhead with a barbell, dumbbells or even a single dumbbell and this next study sheds light on which will activate the supportive trunk musculature to a better extent. Using 15 healthy males, EMG of the superficial core muscles (rectus abdominis, external oblique, and erector spinae) was measured between a seated, standing, bilateral, and unilateral dumbbell shoulder press exercise. This study’s findings show that in order to enhance activation of the superficial core musculature, standing exercises should be used instead of seated exercises, and unilateral upper extremity exercises should be used instead of bilateral upper extremity exercises (14). Thus if we wish to further challenge the trunk of the athletes performing these lifts we would want to progress from a bilateral upper extremity external load such as a barbell to a unilateral upper extremity load such as a kettlebell or dumbbell held by the side and then possibly overhead.

The succeeding 3 studies look at variations of lunges and their various benefits. In the first study a total of 16 recreationally active, college-aged adults participated in an anterior lunge with 4 external-load conditions of 0%, 12.5%, 25%, and 50% of body mass applied while kinematic and ground reaction force data was collected. This study showed that from a kinematic perspective, the lunge involves greater motion at the knee, but from a kinetic perspective the anterior lunge is a hip-extensor dominant exercise and with the addition of external weight the greatest joint kinetic increases were seen at the hip and ankle, with little change in the knee contributions. Thus, kinematically the lunge focuses more joint motion at the knee than ankle and hip but kinetically it remains extensor dominant and increased loading increased ankle and hip contributions with minimal linear knee contributions (12).

In a study with nine men who performed a single-leg squat, forward lunge, and reverse lunge with kinetic data captured using 2 force plates and 3-dimensional kinematic data via a motion-capture system. They observed greater eccentric and concentric peak vertical ground reaction forces during the single-legged squat than during both lunge variations with no differences between the two lunges. Using this evidence appropriately with respect to a joint loading progression from least to most for the hip, could begin with the single-legged squat with progression to the reverse lunge and then finishing with the forward lunge. In contrast, a joint loading progression from least to most for the knee and ankle should begin with the reverse lunge and progress to the forward lunge and then the single-legged squat. So, if you want the least amount of hip joint loading, think single leg squat. If you want the least knee and ankle joint loading, think reverse lunge, which reversely loads the hip joint more. This study can help guide which type of lunge we use in correlation to the joint forces at the hip, knee, and ankle with higher level athletes who are prone to overuse of certain joints, who’s muscle activation are altered by joint mechanics, or who are rehabilitating from pain at any of the above joints (3).

Finally, in 2015, a study was conducted to determine the effects of dumbbell-carrying position on the kinematics and electromyographic (EMG) of the gluteus medius, vastus medialis, vastus lateralis, and biceps femoris during walking lunges and split squats. The 28 subjects performed ipsilateral walking lunges (weight held on the same side as the moving limb), contralateral walking lunges (weight held on the opposite side as the moving limb), ipsilateral split squat, and contralateral split squat in a randomized order in a simulated training session for a 5RM. This study showed a higher eccentric vastus lateralis amplitude during walking lunges with weight held in contralateral arm. The walking lunges with the weight in the contralateral arm resulted in higher eccentric gluteus medius amplitudes as well as peak amplitudes of greater than 90% MVIC. Therefore, the walking lunge with the weight held in the contralateral arm to the moving leg may be optimal to increase the gluteus medius and vastus lateralis maximal strength and activation (16).

Keep an eye out for next week’s Lunging into Stride Length Part 3, where we will discuss Lift Progressions of the Lunge to Optimize Performance

CITATIONS

1. Boren K, Conrey C, Le Coguic J, Paprocki L, Voight M, Robinson TK. Electromyographic analysis of gluteus medius and gluteus maximus during rehabilitation exercise. International Journal of Sports Physical Therapy. 2011;6(3):206-223.

2. Chowdhury, S., & Kumar, N. (2013). Estimation of forces and moments of lower limb joints from kinematics data and inertial properties of the body by using inverse dynamics technique. Journal of Rehabilitation Robotics, 1(2), 93-98

3. Comfort P, Jones PA, Smith LC, Herrington L. Joint Kinetics and Kinematics During Common Lower Limb Rehabilitation Exercises. Journal of Athletic Training. 2015;50(10):1011-1018. doi:10.4085/1062-6050-50.9.05.

4. Contreras, Bret. Force Vector Training (FVT). The Glute Guy, 1 July 2010, Bretcontreras.com/load-vector-training-lvt/.

5. Dwyer MK, Boudreau SN, Mattacola CG, Uhl TL, Latterman C. Comparision of lower extremity kinematics and hip muscle activation during rehabilitation tasks between sexes. J Athl Train. 2010;45(2):181–190

6. Ekstrom RA, Donatelli RA, Carp KC. Electromyographic analysis of core trunk, hip, and thigh muscles during 9 rehabilitation exercises. J Orthop Sports Phys Ther. 2007;37(12):754–762.

7. Farrokhi S, Pollard CD, Souza RB, Chen YJ, Reischl S, Powers CM. Trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. J Orthop Sports Phys Ther. 2008 Jul;38(7):403-9. doi: 10.2519/jospt.2008.2634. Epub 2008 Apr 15.

8. Flanagan et al (2003). Lower extremity biomechanics during forward and lateral stepping activities in older adults. Clinical Biomechanics, 18(3), 2 14-22. Roger W. Earle (2005). Essential of personal training. National Strength and Conditioning Association.

9. Hefzy MS, al Khazim M, Harrison L. Co-activation of the hamstrings and quadriceps during the lunge exercise. Biomed Sci Instrum. 1997;33:360–365.

10. Khaiyat OA, Norris J. Electromyographic activity of selected trunk, core, and thigh muscles in commonly used exercises for ACL rehabilitation. Journal of Physical Therapy Science. 2018;30(4):642-648. doi:10.1589/jpts.30.642.

11. N Boudreau, Samantha & Dwyer, Maureen & Mattacola, Carl & Lattermann, Christian & Uhl, Tim & Medina McKeon, Jennifer. (2009). Hip-Muscle Activation During the Lunge, Single-Leg Squat, and Step-Up-and-Over Exercises. Journal of sport rehabilitation. 18. 91-103. 10.1123/jsr.18.1.91.

12. Riemann BL, Lapinski S, Smith L, Davies G. Biomechanical Analysis of the Anterior Lunge During 4 External-Load Conditions. Journal of Athletic Training. 2012;47(4):372-378.

13. Riemann, Bryan & Congleton, A & Ward, R & Davies, George. (2013). Biomechanical comparison of forward and lateral lunges at varying step lengths. The Journal of sports medicine and physical fitness. 53. 130-8.

14. Saeterbakken AH, Fimland MS, Navarsete J, Kroken T, van den Tillaar R (2015) Muscle Activity, and the Association between Core Strength, Core Endurance and Core Stability. J Nov Physiother Phys Rehabil 2(2): 028-034. DOI: 10.17352/2455-5487.000022

15. Saeterbakken, Atle & Fimland, Marius. (2011). Muscle activity of the core during bilateral, unilateral, seated and standing resistance exercise. European journal of applied physiology. 112. 1671-8. 10.1007/s00421-011-2141-7.

16. Stastny et al (2015). Does the dumbbell-carrying position change the muscle activity in split squats and walking lunges? Journal of Strength and Conditioning Research, 29(11), 3177-3187. Thomas R. Baechle et al (2013) Essentials of strength training and conditioning. National Strength and Conditioning Association.

17. Stuart MJ, Meglan DA, Lutz GE, Growney ES, An KN. Comparison of intersegmental tibiofemoral joint forces and muscle activity during various closed kinetic chain exercises. Am J Sports Med. 1996; 24(6):792–799.
    

Lunging Into Stride Length Part I: Introducing the Benefits of a Functional Lunge

Here’s our latest in the Sports Health section from Dr. Jonathan Hartman and Dr. Marshall LeMoine. This topic has been broken out into 3 parts due to its’ length so keep an eye out every first Wednesday of the month to stay on top of this great article.

INTRODUCTION

With any high-level athletics training, it is important to keep the “force vector training theory” in mind. This trains the athlete as close to their sport’s specific body position while opposing or resisting the most exact line of pull, or direction of resistance that they will encounter when playing their full speed sport. This will vastly help the athlete attain the most sport specific muscular adaptations and the correct sport movement patterns, for best carryover onto the field or court (4). We should strive to train each athlete according to the proper sport specific force vectors with optimal muscle activation patterns which at times may involve ipsilateral lower and upper extremity sport patterning, (seen with the squat for a jumping athlete), or a contralateral upper and lower extremity sports pattering, (seen with the lunge for a running athlete). In the past articles I have broken down an ipsilateral pattern with the squat and deadlift, and thus in this article I will discuss the contralateral pattern enhancing strength gains that can be attained using the lunge.

This article will focus on the benefits of the step back, forwards, and stationary lunge as it is a functional multi-joint exercise that is commonly integrated into lower extremity progressive athletic optimization programs. This exercise has vast benefits as it can mimic the reciprocal contralateral patterns seen in sports activities, can target single leg stance trunk stability and control, can aid in enhancing single limb push off and stability, and can be modified and progressed in a vast array of ways to target specific sports specific muscle groups of the lower extremities and trunk. When compared to a closed chain bilateral lower extremity exercise such as a squat, this lift is primarily performed with the majority of the weight on a single lower extremity and thus we can overload the muscles of the supporting lower extremity with less overall weight therefore reducing the total load on the athlete’s spine. I will also give insight into how to progress this seemingly simple exercise into many different ways, using many different external aids, as well as highlight which joints and parts of the movement are most susceptible to form break down. The supportive studies for this article will shed light on how the evidence behind the lunge will closely simulate the strength adaptations needed for the sport specific muscles involved in running and single leg stride sports. There is also evidence to support how the differing aids and variations of this lift will affect certain muscles and joints, as well as this lift’s role in enhancing pelvic and trunk stability and balance.

Keep an eye out for next month’s Lunging into Stride Length Part 2, where we will discuss the research based evidence behind lunge variations

CITATIONS

1. Boren K, Conrey C, Le Coguic J, Paprocki L, Voight M, Robinson TK. Electromyographic analysis of gluteus medius and gluteus maximus during rehabilitation exercise. International Journal of Sports Physical Therapy. 2011;6(3):206-223.

2. Chowdhury, S., & Kumar, N. (2013). Estimation of forces and moments of lower limb joints from kinematics data and inertial properties of the body by using inverse dynamics technique. Journal of Rehabilitation Robotics, 1(2), 93-98

3. Comfort P, Jones PA, Smith LC, Herrington L. Joint Kinetics and Kinematics During Common Lower Limb Rehabilitation Exercises. Journal of Athletic Training. 2015;50(10):1011-1018. doi:10.4085/1062-6050-50.9.05.

4. Contreras, Bret. Force Vector Training (FVT). The Glute Guy, 1 July 2010, Bretcontreras.com/load-vector-training-lvt/.

5. Dwyer MK, Boudreau SN, Mattacola CG, Uhl TL, Latterman C. Comparision of lower extremity kinematics and hip muscle activation during rehabilitation tasks between sexes. J Athl Train. 2010;45(2):181–190

6. Ekstrom RA, Donatelli RA, Carp KC. Electromyographic analysis of core trunk, hip, and thigh muscles during 9 rehabilitation exercises. J Orthop Sports Phys Ther. 2007;37(12):754–762.

7. Farrokhi S, Pollard CD, Souza RB, Chen YJ, Reischl S, Powers CM. Trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. J Orthop Sports Phys Ther. 2008 Jul;38(7):403-9. doi: 10.2519/jospt.2008.2634. Epub 2008 Apr 15.

8. Flanagan et al (2003). Lower extremity biomechanics during forward and lateral stepping activities in older adults. Clinical Biomechanics, 18(3), 2 14-22. Roger W. Earle (2005). Essential of personal training. National Strength and Conditioning Association.

9. Hefzy MS, al Khazim M, Harrison L. Co-activation of the hamstrings and quadriceps during the lunge exercise. Biomed Sci Instrum. 1997;33:360–365.

10. Khaiyat OA, Norris J. Electromyographic activity of selected trunk, core, and thigh muscles in commonly used exercises for ACL rehabilitation. Journal of Physical Therapy Science. 2018;30(4):642-648. doi:10.1589/jpts.30.642.

11. N Boudreau, Samantha & Dwyer, Maureen & Mattacola, Carl & Lattermann, Christian & Uhl, Tim & Medina McKeon, Jennifer. (2009). Hip-Muscle Activation During the Lunge, Single-Leg Squat, and Step-Up-and-Over Exercises. Journal of sport rehabilitation. 18. 91-103. 10.1123/jsr.18.1.91.

12. Riemann BL, Lapinski S, Smith L, Davies G. Biomechanical Analysis of the Anterior Lunge During 4 External-Load Conditions. Journal of Athletic Training. 2012;47(4):372-378.

13. Riemann, Bryan & Congleton, A & Ward, R & Davies, George. (2013). Biomechanical comparison of forward and lateral lunges at varying step lengths. The Journal of sports medicine and physical fitness. 53. 130-8.

14. Saeterbakken AH, Fimland MS, Navarsete J, Kroken T, van den Tillaar R (2015) Muscle Activity, and the Association between Core Strength, Core Endurance and Core Stability. J Nov Physiother Phys Rehabil 2(2): 028-034. DOI: 10.17352/2455-5487.000022

15. Saeterbakken, Atle & Fimland, Marius. (2011). Muscle activity of the core during bilateral, unilateral, seated and standing resistance exercise. European journal of applied physiology. 112. 1671-8. 10.1007/s00421-011-2141-7.

16. Stastny et al (2015). Does the dumbbell-carrying position change the muscle activity in split squats and walking lunges? Journal of Strength and Conditioning Research, 29(11), 3177-3187. Thomas R. Baechle et al (2013) Essentials of strength training and conditioning. National Strength and Conditioning Association.

17. Stuart MJ, Meglan DA, Lutz GE, Growney ES, An KN. Comparison of intersegmental tibiofemoral joint forces and muscle activity during various closed kinetic chain exercises. Am J Sports Med. 1996; 24(6):792–799.
    

The Deadlift: Purposeful and Functional Loading

AUTHORS
Dr. Jonathan Hartman PT, DPT, OCS, CSCS, FAAOMPT
Dr. Marshall LeMoine PT, DPT, OCS, SCS, CSCS, FAAOMPT

QUICK LINKS
Introduction
Anatomical and Movement Faults
Evidence
Deadlift Movement Fault Guide
Citations

INTRODUCTION

Can you imagine bending over and staring down at a barbell with weights stacked on each side adding up to over 1000 lb and then lifting that bar from a dead stop off the ground to above your knees? Welcome to the deadlift. A closed chain, dynamic integrated motion, where stammering weight can be moved from the ground, to above the knees, challenging the entire muscular system. Athletes can perform this lift with extremely high weight (world record 1041 pounds), thus dynamic form breakdown can have serious consequences, most commonly at the low back, shoulders, and knees (1). The deadlift exercise is widely used by athletes of many sports, as well as recreational lifters, to enhance power and strength of the posterior chain musculature. How does it measure up to other full body dynamic weighted lifts? Does it really target specific posterior chain muscles or larger groups of muscles more than other complex weighted lifts? And what are the most common faults and injuries seen with power lifts and how can we as movement specialists avoid them? This article will focus on the answers to the preceding questions, shed light on the most common faults seen at each phase of the standard deadlift, look into current evidence to guide when and why one would choose this lift, and describe how to best perform it to target the most sport specific muscles. Enjoy the read!

ANATOMICAL & MOVEMENT FAULT

A 2016 meta-analysis used a systematic review to show that the low back, shoulder, and knee regions were the most commonly injured locations found among varying full body weight and power lifting exercises (1). The deadlift is a full body closed chain integrated movement that can be done a number of different ways with differing equipment. The main muscles used are commonly referred to as the posterior chain, most notably the gluteals, hamstring, erector spinae, and adductor muscles, as well as entire abdominal cavity. There are a multitude of ways to break up any lifting exercise, but I will break up the standard deadlift into three phases: the static start phase, the pull or ascent phase ending with the lockout, and the descent phase. This will allow us to simplify the faults, and match them to the phase they are most occur in. It is important to remember that the individual athlete’s anthropomorphic form will dictate function, and thus as athletes start to get more comfortable with the complexities of the lift or are progressing in rehabilitation from various injuries their form can change. That being said, the underlying principles of this section will guide the clinician towards honing in on areas of commonly seen movement faults and sites of tissue break down to make the lift as safe and effective as possible.

Prior to the lift have the athlete watch you or another person perform the lift from multiple planes while explaining the what, where, and why of the most common faults seen at each phase. It may be important to talk about proper stance width, grip type, external equipment use (such as wrist wraps, weight belts, shoe selection, knee wraps, bar type), and lifting goals with special emphasis on the muscles of focus and purpose of the lift itself. Watch the patient perform this complex power lift from at least 2 planes in order to get the full kinematic picture before deciding what to optimize.

Tune in next week to learn the different phases of deadlift…

Here’s the continuation of the The Deadlift: Purposeful and Functional Loading, and below are the different phases of deadlift

A. Static Start Phase

At the starting position of the deadlift we want our athletes in a position that will maximize perpendicular bar path and vector force from the ground without putting any anatomical structures under excessive or unnecessary shearing, compressive, or torsional forces. This means starting with specific resting muscle tension and stored potential energy, with the hips higher than the knees, weight back into the heels, and the bar making contact with their shins. Many of the studies in this article that have focused on the deadlift or power lifting have shown that the low back is the overall most common source of tissue breakdown. Therefore let’s take a moment to unpack why this could be. It is thought that the correct way to start this lift is with the weight resting on the floor, where the athlete must have adequate low back, hip, knee and ankle range of motion and be able to support all structures in this position with significant tissue wind up and potential energy. It is erroneous to think that every lifter is capable of starting this lift from the floor with a safe neutral lumbar spine position, considering that each person's torso, femur, tibia, and arm length vary drastically. This, plus soft tissue factors lead to limits in starting position with the weight on the floor. The most common movement fault and poor compensatory pattern that can be seen in order to lift a bar from the ground at this phase is starting the lift with a posterior pelvic tilt with lumbar spine flexion. The underlying principle is that in order to reduce low back injury the athlete must maintain a neutral lumbar lordosis from the start to the end of the lift. Using both in vivo and in vitro analysis with multiple modes of real time imaging and biomechanical computer modeling programs it has been shown conclusively that as the lumbar spine becomes more and more flexed the contribution of the lumbar stabilizing musculature decreases and the supportive force generated by the ligaments and bony tissue increases, resulting in higher shearing forces and increased likelihood for low back injury (11-12). Thus each athletes individual safe full range of motion for this lift starts with the lowest possible bar position prior to a posterior pelvic tilt. Accommodations for bar height can be made by having the athlete start with the weights elevated on steps, block risers, barbell plates themselves, or assisted rack risers. Be sure to educate the athlete that each lifter should start and end the lift with a neutral spine and due to each athlete’s individual body proportions there is no single right way for every athlete to perform the same lift, and this may change with tissue adaptations throughout life.   

Another way to add to low back support is through increased trunk stability and activation via ancillary exercises as shown in past months articles. Prior to and throughout the entirety of the dynamic phases of the lift the athlete must activate his or her core musculature in order to increase intraabdominal pressure which has been shown to further add to trunk active stiffness and reduce the sole reliance on the low back musculature. Breathing with these lifts should be done after the entire lift is completed before the next rep with the weight on the ground or at the top of the lift just before the descent, but never in the pull or descent phases. During these phases the systems maximal effort is required, and thus keeping this intraabdominal pressure constant will lead to improved overall trunk stability.

Another area of concern is shoe choice which may affect starting dorsiflexion position, and thus affect trunk and hip starting position. This can be addressed by trying the lift with varying external heel heights or insoles and then getting a shoe to match. Secondarily, since this is a power exercise we want our athletes to choose a shoe whose sole provides a firm, wide, flat stable base which can correct for excessive medial arch collapse if needed. This is very important as we want to make sure that no ground reaction force is lost due to an air or large foam soled running or cross training shoe. Providing a firm stable base to push from, with the deadlift has been shown to reduce the lift’s overall force production and muscle activation (6). In summary for the starting position, make sure the athlete starts with a neutral spine, avoiding a posterior pelvic tilt with a strong abdominal bracing engagement and using a shoe that allows for correct body position accommodating any anatomical foot variances from the ground up if needed.   

B. Pull/Ascent Phase

A poor movement compensation commonly seen at the start of the lift is when athletes initiate the pull with a superior eye gaze going into cervical hyperextension, which can lead to cervical structures being compressed and sheared. There are however some schools of thought that purposefully promote cervical spine hyperextension with weight lifting in order to enhance and increase the lumbar spine extension needed for the attempted weight. It is said that the cervical and the lumbar spine both represent developmentally, what is called a secondary spinal curve, and thus have a deeply rooted connection. where cervical spine extension will promote, mirror, and enhance lumbar spine extension. As this connection is still theory, a common way to reduce balance is to have athletes look upwards, reducing the ability for the body to right itself visually and vestibularly. It is safest to keep our athletes close to cervical spinal neutral as possible, with a constant chin neck angle between 60 to 90 degrees, thus avoiding excessive cervical extension and limit stress on the passive structures of the cervical spine. A unique way to train neutral cervical spine position is to have the athlete hold a softball or tennis ball under their chin by nodding down on the ball, pressing it against their manubrium/ jugular notch but be sure to match the chin neck angle to the size of the ball. Next have them perform the deadlift unweighted for form, while holding the ball in place with the pressure from their chin. This will not only turn on the deep neck flexors adding cervical spine stability but it will show them that their eye gaze must change as they become up-righted throughout the lift.

Next, in order to maximize the perpendicular work force during the entire pull phase of the lift it is pertinent that the bar path is a straight line that is perpendicular to the ground at all times. The bar should stay as close to the lifters shins and body as possible, avoiding any sagittal plane motions. As the bar travels away from the shins and body there is a linear increase in the moment arm from the hips, which adds increased shear and strain stressors on the low back, as well as a linear loss in perpendicular power and energy that can and should be corrected. The movement specialist can best identify this fault by watching the bar path from the lateral view. As previously stated, the bar should stay in contact with the shins with weight being more into the heels, hence why many serious lifters may prefer to wear thin shin guards to prevent scrapping the shins. One common fault that can be seen as the athlete clears their knees with the bar, is that the athlete pulls the bar posterior losing a perpendicular path to meet their hips, to finish the lift standing erect. To facilitate a straighter bar path simply have the athlete squeeze their glutes and thrust their hips forward to the bar immediately after the bar passes their knees, instead of pulling the bar back to meet their hips. This will lead to less energy lost in the sagittal plane and a safer constant strain on the low back. Other ways that have been listed in various resources to cue a straight bar path is by using an unlocked Jones machines which uses  supportive uprights, videotaping the lift with post lift assessment and reflection, external verbal cues, tactile cues by wearing shin guard and having the athlete purposefully scrape the shin to keep the bar in contact with the body. Also, during the pull phase the majority of loaded tibiofemoral motion will be completed and thus it is pertinent to talk about the most common movement faults seen at the knee and how to avoid them. The most common movement fault seen here is tibiofemoral adduction with or without internal rotation, which can be seen as the knee dives inwards and the thigh rotates. This can be further increased if the foot is set into excessive eversion with the base of support too wide leading to the athlete’s inability to keep the knees tracking over the toes (leading to more femoral Adduction with internal rotation). This fault can lead to increased ligamentous and soft tissue stress and increase the likelihood of patellofemoral irritation. It is important to work with our athletes to find the correct stance which allows them to keep their knees tracking over their toes, avoiding both primary and relative femoral adduction and internal rotation. Also, make sure if the athlete is using knee wraps, as is common with weighted deadlifts, that the knee wrap is applied from medial to lateral thus promoting a tactile facilitation into tibiofemoral external rotation and abduction as wrapping the joint from lateral to medial may seem picky but it will promote facilitation of the athletes knee into a faulty position which is not advised.  Finally at the end of the pull we can focus on the low back during the terminal bar position, referred to as the lockout phase. A common fault at this phase is for the athlete to perform the lift in lumbar hyperextension, which can lead to facet joint irritation and undue stress on the low backs passive structures as well as decreased the total time under tension of the dynamic muscular structures. Focus on cueing them to stand straight up and finish the lift by squeezing the glutes and lift the chest with the lumbar spine in neutral not by extending the low back. This poor compensatory pattern may be due to the athlete’s lack of control towards the end of the lift requiring a bony stop to reach the lockout phase or just misunderstanding of how the lift should look at its terminal phase as loaded end range facet joint positions are not advised at the lockout phase of the deadlift.

C. Descent Phase

In this phase the athlete will either be slowly lowering, or dropping the weight, depending on the amount of weight. It is important that it is done with a neutral spine, avoiding a posterior pelvic tilt.

Again, look at lifts from at least 2 planes/views in order to get the full kinematic picture before deciding on what to optimize. See below for a much more detailed version of the lift broken down into 2 planes can be seen below in the “Deadlift Movement Fault Guide” and “Quick Look Movement” along with the supplementary videos and pictures. I strongly urge you as a movement specialist to further look into books by Dr. Stuart McGill, professor of spine biomechanics at the University of Waterloo, who’s books focus on evidence based lumbar spine and high level sports related lifts and motions. Also, look into Mark Rippetoe’s “Starting Strength” book for a professional biomechanical power lifting approach, or Ma Strength’s recently translated Chinese evidence based Olympic lifting manual and videos on various social media where you can get a plethora of different evidence based training tips and ideas. Along with these great resources I frequently look into published kinematic studies of various lifts. Having said this if you follow the recommendations above of the most common faults seen at each phase you can reduce the chances of unnecessary tissue stress and strain leading to increased risk for pain or injury for your athletes.

Follow us next week to conclude with the evidence in muscle activation during the deadlift compared with other strength lifts.

For the final segment of the The Deadlift: Purposeful and Functional Loading, and below lists the evidence in muscle activation for the deadlift compared to other strength lifts.

EVIDENCE

Now we will use evidence to look at the specific muscles the deadlift targets, how it measures up to other power and strength lifts, the effects of different equipment used with the deadlift, who could benefit from this mode of training, the effects of differing grips and supplementary perturbation training with this lift.

This first study focuses on hamstring activation due to its inherently large muscular involvement in the deadlift movement. Hamstring muscle power deficit and muscular ratio imbalance between the quadriceps and hamstring muscles have been proven many times over to be strong predicting factors of future and past hamstring strains. Thus, in this study 11 weight trained, high level, male athletes were used in order to compare the single leg deadlift, versus the hamstring curl, and the squat, for 3 repetitions at 75% 1RM. They measured the biceps femoris and semitendinosus eccentric and concentric muscle activation in the three different exercises. They found that the concentric hamstring curl and single leg deadlift elicited the greatest integrated and highest peak EMG activity of the hamstrings, with no significant difference between these two exercises. The concentric squat showed approximately 50% the integrated EMG activity and 70% the highest peak hamstring activation (9).

Mcallister et al. compared muscular EMG activation eccentrically and concentrically using the leg curl, good morning, glute-ham raise, and Romanian deadlift exercises. This study used twelve healthy, weight-trained men who performed duplicate trials of one repetition at 85% 1RM for each lift in random order. The study monitored the erector spinae, gluteus medius, semitendinosus, biceps femoris, and medial gastrocnemius, and showed that there are significant differences in activation within the same muscles when comparing all exercises eccentrically to concentrically (8).

When looking at EMG muscle activation of the gluteus maximus, biceps femoris, and erector spinae with the barbell deadlift, hex bar deadlift and hip thruster for 1RM, we see that there is small, yet important differences in muscle activation based on each exercise chosen. When Andersen et al. compared these three lifts with thirteen healthy resistance-trained men, aged 20–25 years old, they found that the barbell deadlift was clearly superior in activating the biceps femoris compared to the hex bar deadlift and hip thrust. The hip thrust showed slight favor towards the highest gluteus maximus activation and all three exercises had similarly high erector spinae activations. During a lift with maximum loading, the hip thrust, had the highest, although insignificant, muscle activation for the gluteus maximus, particularly in the upper phase of the movement.  The two standing exercises had possibly decreased tension on the hip extensors. On the other hand, the hex bar deadlift generally provided the lowest muscle activation for all leg these muscles tested. These slight changes in muscle activation can be used when we are looking for athletic optimization and correct exercise choice for the muscles we want to target (2).

Next let's take a look at Camara et al. whose study compared muscle activity with the barbell deadlift and hex bar deadlift, using submaximal loading among 20 resistance-trained men. Subjects performed the hex bar and straight bar deadlift for 3 reps at 65 and 85% 1 RM. The study used electromyography (EMG) to calculate the muscle activation of the vastus lateralis, biceps femoris, and erector spinae, as well as a force plate to measure peak force, peak power, and peak velocity. This study found significantly greater normalized EMG values of  the vastus lateralis for both the concentric and eccentric phases of the hexagonal-barbell deadlift and significantly greater EMG values of the bicep femoris during the concentric phase and of the erector spinae during the eccentric phase with the barbell deadlift. The hexagonal-barbell deadlift demonstrated significantly greater peak force, peak power, and peak velocity values than those of the straight-barbell deadlift. These results suggest that the lift variations led to different patterns of muscle activation and that the hexagonal barbell may be more effective at developing maximal force, power, and velocity and that for those with lower back related symptoms the hex bar deadlift may be more optimal due to its ability to more evenly distribute the load among all weight bearing joints and reduce the moment at the lumbar spine. Conversely, one should choose the straight bar deadlift if the goal of the training session is to emphasize activation of the lumbar and hamstring musculature (5).  

 The next study looked at subjects with mechanical low back pain to see which factors at initial assessment would predict if a subject would have a beneficial or poor outcome with a deadlift strength training program. The study used 35 subjects, 26-60 years old, with a dominating pattern of nociceptive mechanical low back pain, with a duration for at least 3 months. Each subject’s age, sex, and body mass index were taken and each subject completed the Patient-Specific Functional Scale, the Roland-Morris Disability Questionnaire, as well as a 100mm visual analog scale. Each subject was taken through a movement control test battery made up of 7 lumbar hip dissociation tests, and was timed on 3 trunk muscle endurance tests (the side bridge, prone bridge, and the Biering-Sørensen prone extension). The deadlift exercise was then performed 12 times during an 8-week period. The results showed that the higher the pain intensity, >60mm on VAS, and the lower performance on the Biering-Sørensen test, <60 seconds at initial evaluation, the less likely that participants were to benefit from deadlift training regime. The most robust predictor being the Sørensen hold time. The Sørensen test was postulated to be more significant than the VAS scale due to its ability to test the activation capacity of the stabilizing hip and back extensors for a sustained period. Thus if low endurance of the hip and back extensors and high pain intensity are found at initial evaluation with an individual with mechanical low back pain, other interventions should be considered to improve these tests prior to initiating deadlift training for the most beneficial outcomes (4).

It has been suggested that the inclusion of instability devices in resistance training may increase muscle activation in the trunk and extremities to a greater extent than traditional resistance training methods. Chulvi-Medrano et al. tested this theory while monitoring lumbar multifidus spinae, thoracic multifidus spinae, the lumbar erector spinae, and thoracic erector spinae through EMG, while measuring pull force output through a load sensor attached from the bar to the ground using 31 resistance-trained participants. Each participant performed a 5 Sec MVIC isometric deadlift pull followed by 5 repetitions with 70% 1RM weight while standing on flat ground, on a T-Bow (U-shaped rocker board with coronal plane motion as an unstable surface), and on a Bosu trainer (flat side down). This study showed that performing deadlift maximal holds and dynamic deadlifts under stable conditions produces more EMG activity of the back musculature and more overall pulling force. Therefore, the use of instability devices in deadlift training does not increase pull force performance, nor does it provide greater activation of the paraspinal/ trunk posterior chain muscles (6).  

When running my searches for the highly discussed topic of grip types, I came across a very interesting master’s thesis study in 2011 by Beggs, which focused on this very controversial topic of grip type and muscle activation. Powerlifting websites commonly have many questions pertaining to this topic with such questions as: “Should both hands be pronated? Should I use an alternate grip? Which hand should be supinated or pronated if I do use an alternate grip? This study examined muscle activation and relative joint angles during a barbell deadlift while using either a double‐pronated or right and left overhand/underhand (OU) grip with each participant testing 3 grips total. This study used ten weight‐trained individuals average age of 21.2 years old who performed the barbell deadlift with 60% and 80% of their 1‐repetition maximum with wrist straps allowed for double-pronated 80%1 RM only. The EMG recordings were taken of the left and right biceps brachii, brachioradialis, upper trapezius, and upper latissimus dorsi, and motion capture was used to measure angles of the wrist, elbow, knee, and hip. This study shows some important considerations for upper extremity athletes who want to start, or are currently performing this lift, and already have increased game and practice stress placed at the elbow and wrist or who are prone to the overuse and underuse of certain upper extremity muscles. In summation, the supination grip hand showed significantly greater biceps EMG activity than ALL pronated‐hand conditions at equivalent intensity and significantly less Brachioradialis EMG activation. Surprisingly The trapezius and latissimus dorsi showed no statistically significant findings with respect to grip. When looking at joint angles supination caused significantly more wrist flexion, elbow extension, and neither knee nor hip angles were significantly different at any point between the three grip variations at either 60 or 80% of 1‐RM (3). If there is no need to be concerned with specific upper extremity muscle overuse and the athlete is to use an alternate grip the most important thing is to watch them lift with each option and then choose the grip that the athlete is most confident with as well as the one that shows a superior normalization of upper extremities and spinal structures.

It is pertinent to use the research and anatomical fault guidelines to optimize our athletes in high level performance power lifts in order to better target sport specific movement and musculature as well as to reduce unnecessary stress and strain on joints and body regions already placed under a high demand.

DEADLIFT MOVEMENT FAULT GUIDE

“There is no ONE perfect way for EVERY athlete to perform the same lift, but there is ONE perfect way for EVERY individual athlete to  perform each specific lift which may change throughout their life.”

Lateral View:

• Chin neck angle constant 60-90 (Cue: Hold a tennis ball under chin- DNF, Stick on back/ head, allow gaze to follow body)

• External auditory meatus over shoulder

• Slightly lifted chest, knees bent, butt must always start higher than the knees at the start (this is not a squat)

• Pull shoulders together, engage mid traps, reduce scapular upward rotation (rhomboid overuse) and elevation (upper traps overuse) on the start

• Hand width will vary but will be outside the thighs with feet about hips distance apart

• Thumbs always under bar (Alternate grip if heavy but check to see which ER/IR arm shows the most neutral spine and normalized positioning )

• Abdominal Brace (Breath in and out at the bottom of deadlift prior to pull phase)

• Lumbar spine neutral to start, without trunk rotation via visibility of both shoulders (Avoid starting in a posterior pelvic tilt ALWAYS)

• Feet hips distance apart or slightly wider (Should only see 1 foot from this view as they will be in the same frontal plane)

• Feet up to 30 degrees Eversion

• Initiate by sitting back into heels and by pulling the bar towards the shins just prior to the pull phase

• Initiate with a hip drive and glutes squeezed towards the bar, then allow knee extension and continue with a 1:1 knee and hip extension rate (Do not pull the bar to your hips, instead thrust your hips to the bar)

• Trunk must lean forward with a neutral spine to make the correct bar path

• Pull Sequence  (Hip extension and Knee extension 1:1 ratio; STOP with back in neutral, Hips flexed, Knees flex, Bar touches risers/ ground)

• Bar is never more than 1” from body to reduce spinal torque and lost energy

• Avoid lumbar spine hyperextension at lockout (Seen with hips anterior to shoulders) Stop in lumbar spine neutral, chest lifted, and glutes squeezed

• Knees pulled out over toes 1-3, Avoid excessive tibiofemoral anterior translation

• Bar starts and ends over mid foot (Straight and perpendicular bar path to the floor)

Posterior View:

• Chin neck angle constant 60-90 (Cue: Hold a tennis ball under chin- DNF, Stick on back/ head, allow gaze to follow body)

• No cervical side bend, or excessive hinge creasing

• Slightly lifted chest, knees bent, butt must always start higher than the knees at the start (this is not a squat)

• Shoulders pulled together and engaged mid traps (try to reduce scapular upward rotation from rhomboids and elevation form upper traps on the start)

• Hand width will vary but will be outside the thighs with feet about hips distance apart

• Thumbs always under bar (Alternate grip if heavy but check to see which ER/IR arm shows the most neutral spine and normalized positioning

• Pull shoulders together, engage mid traps, reduce scapular upward rotation (rhomboid overuse) and elevation (upper traps overuse) on the start

• Body centered on the Bar (Hands equal distance from body, checked via distances from the plates and knurling of the bar)

• Abdominal Brace (Look for excessive lateral trunk shift/ lean or lateral posterior wall creasing, Breath in and out at the bottom of deadlift prior to pull phase)

• Lumbar spine neutral to start (Avoid starting in a butt wink/ posterior pelvic tilt ALWAYS)

• Feet hips distance apart or slightly wider

• Feet up to 30 degrees Eversion (Lateral toe sign should be symmetrical)

• Initiate by sitting back into heels and by pulling the bar towards the shins

• Initiate with a hip drive and glutes squeezed towards the bar, then allow knee extension and continue with a 1:1 knee and hip extension rate (Do not pull the bar to your hips, instead thrust your hips to the bar)

• Trunk must never shift right or left and both legs should extend at the same rate

• Trunk must lean forward to make correct bar path

• Pull Sequence  (Hip extension and Knee extension 1:1 ratio; STOP with back in neutral, Hips flexed, Knees flex, Bar touches risers/ ground)

• Avoid lumbar spine hyperextension at lockout (seen via creasing) Stop in lumbar spine neutral, chest lifted, and glutes squeezed

• Knees pulled out over toes 1-3, Avoid femoral adduction/ internal rotation (Use theraband as tactile cue as in squatting)

• Bar starts and ends over mid foot (Straight and perpendicular bar path to the floor)

Quick Look Movement:

• Start Position: Spinal neutral (no posterior pelvic tilt), Feet hips distance, Sustained chin tuck (60-90), butt higher than knees at all times

• Abdominal Brace (Breath in and out at the bottom of the deadlift, never during dynamic motion)

• Sit back and load body, then initiate with hip hinge and glute squeeze, driving hips towards the bar followed by knee extension

• Pull Sequence  (Hip extension and Knee extension 1:1 ratio; STOP with back in neutral, Hips flexed, Knees flex, Bar touches risers/ ground)  

• Avoid femoral adduction/ internal rotation

• Motion ends at the lockout with athlete in lumbar spine neutral, chest lifted, and glutes squeezed

• Maintain spinal neutral for weight drop or controlled lowering

Research Quick Reference:

• Athletes with mechanical low back pain least likely to benefit from deadlift training have a Sørensen <60 seconds and a VAS of >60mm (6/10)

• Men at 65% to 85% 1 RM reduce lumbar spine stress and increase vastus lateralis EMG activity,  greater peak force, peak power, and peak velocity with Hex bar deadlift.

• Use straight bar deadlift to emphasize activation of the lumbar region and hamstrings.

• The use of instability devices in deadlift training does not increase force performance, nor does it provide greater activation of the paraspinal/ trunk posterior chain muscles

• At 75% 1RM the leg curl and single leg deadlift involve the hamstrings to a similar degree, while the back squat involves about 50% the integrated and 70% the peak hamstring EMG activity.

• There is significantly different muscle activation during each lift’s eccentric and concentric phases.

• Pronated or supinated grip will change wrist and elbow joint angles and lead to differing upper extremity muscular EMG activation when performing deadlift at 60% and 80% 1 RM, thus be mindful of grip with upper extremity repetitive athletes to avoid commonly overused tissues.

CITATIONS

1. Aasa U, et al. Br J Sports Med 2017;51:211–220. doi:10.1136/bjsports-2016-096037

2. Andersen, Vidar, et al. “Electromyographic Comparison Of Barbell Deadlift, Hex Bar Deadlift And Hip Thrust Exercises.” Journal of Strength and Conditioning Research, 2017, p. 1., doi:10.1519/jsc.0000000000001826.

3. Beggs, Luke Allen, "Comparison of muscle activation and kinematics during the deadlift using a double-pronated  and overhead/underhand grip” (2011). University of Kentucky Master's Theses. 87.

4. Berglund, Lars, et al. “Which Patients With Low Back Pain Benefit From Deadlift Training?” Journal of Strength and Conditioning Research, vol. 29, no. 7, 2015, pp. 1803–1811., doi:10.1519/jsc.0000000000000837.

5. Camara, Kevin D., et al. “An Examination of Muscle Activation and Power Characteristics While Performing the Deadlift Exercise with Straight and Hexagonal Barbells.” Medicine & Science in Sports & Exercise, vol. 48, May 2016, p. 470., doi:10.1249/01.mss.0000486413.06515.da.

6. Chulvi-Medrano, Iván, et al. “Deadlift Muscle Force and Activation Under Stable and Unstable Conditions.” Journal of Strength and Conditioning Research, vol. 24, no. 10, 2010, pp. 2723–2730., doi:10.1519/jsc.0b013e3181f0a8b9.

7. Distefano LJ, Blackburn JT, Marshall SW, Padua DA. “ Gluteal muscle activation during common therapeutic exercises.” J Orthop Sports Phys Ther. 2009 Jul;39(7):532-40. doi: 10.2519/jospt.2009.2796.

8. Mcallister, Matt J., et al. “Muscle Activation During Various Hamstring Exercises.” Journal of Strength and Conditioning Research, vol. 28, no. 6, 2014, pp. 1573–1580., doi:10.1519/jsc.0000000000000302.

9. Wright, Glenn A., et al. “Electromyographic Activity of the Hamstrings During Performance of the Leg Curl, Stiff-Leg Deadlift, and Back Squat Movements.” Journal of Strength and Conditioning Research, vol. 13, no. 2, 1999, pp. 168–174., doi:10.1519/00124278-199905000-00012

10. Fisher, J., et al., A randomized trial to consider the effect of Romanian deadlift exercise on the development of lumbar extension strength, Physical Therapy in Sport (2012), doi:10.1016/j.ptsp.2012.04.001

11. McGill, S.M. 2002. Low Back Disorders: Evidence-Based Prevention and Rehabilitation. Champaign, IL: Human Kinetics. 4D WATBAK biomechanical computer model, version 2.0.3. 1999. Faculty of Applied Health Sciences, University of Waterloo, Ontario, Canada.

12. McGill, Stuart. Ultimate Back Fitness and Performance Fourth Edition .Waterloo, Ontario Canada, 2009. Print. (P.73)

13. Rippetoe, Mark., and Lon Kilgore. Starting Strength: Basic Barbell Training.3rd ed. Wichita falls, Tx: Asagaard Co, 2011. Print.

14. Robbins, David CSCS, NASM-CPT, "A Comparison Of Muscular Activation During The Back Squat And Deadlift to the Countermovement Jump" (2011). SHU Theses and Dissertations. 1.

15. Schellenberg F, Taylor WR, Lorenzetti S. Towards evidence based strength training: a comparison of muscle forces during deadlifts, goodmornings and split squats. BMC Sports Science, Medicine and Rehabilitation. 2017;9:13. doi:10.1186/s13102-017-0077-x.

Barbell Hip Thrust: The Gluteus Maximus’ Best Friend

AUTHORS
Dr. Jonathan Hartman PT, DPT, OCS, CSCS, FAAOMPT
Dr. Marshall LeMoine PT, DPT, OCS, SCS, CSCS, FAAOMPT

QUICK LINKS
Introduction
Anatomy
Evaluation
Exercise Progression with video
Quick Look: Movement
Citations

INTRODUCTION

Over the past 10 years we have seen an increase in many new innovative ways to strengthen muscles. One exercise that has gained vast popularity is the barbell hip thrust; but is it effective for muscle activation, hypertrophy, and strength gains and does it correlate to athletic performance enhancement? This and more will all be covered in this throughout this post as we dive into the anatomy and kinematics of the hip thrust, reasoning for how and why to use the hip thrust, and how it compares to other full body lower extremity exercises.

When thinking of training movement for higher-level athletes we have to incorporate sport specific training motions. One way of doing this is by using the “force vector training theory”. Which is based on the principle that the most sport specific muscular adaptations and movement enhancing carryover will be derived from training the athlete in their sport specific body position to directly oppose or resist the most exact line of pull, or direction of resistance that they will encounter when playing their full speed sport (8). Basically, we should be training each athlete according to the proper sport specific force vectors and optimal muscle activation patterns (8).

End range hip extension strength and force generation for horizontal acceleration used in sprinting, soccer, football, and many other professional sports can be very important and few exercises currently focus on this concept. The barbell hip thrust is inherently different from other forms of closed chain lower extremity training modes such as the squat or deadlift due to the fact that it imposes a anteroposterior vector load rather than a superior inferior axial vector load. Research is now showing that this horizontal force training application can lead to increased sprinting speeds as well as other sport specific adaptations thought to mainly be obtained through axially loaded exercises (2).

ANATOMY

Anatomically I will focus mainly on the gluteus maximus muscle as it pertains to the barbell hip thrust, as this is one of the main muscles of interest in current literature when looking at strength, power, and injury prevention of the lower quarter. The gluteus maximus is a multiplanar muscle that has been proven to aid in knee and pelvic/ trunk stability. In Addition, it’s proper functioning has been shown to have a protective effect against many lower and upper extremity injuries and is a fundamental muscle required for all lower (and the majority of upper) extremity ballistic sport movements. The gluteus maximus has been linked time and time again to its role in the tibiofemoral joint’s frontal plane moment by the many articles published by Powers et al. A single gluteus maximus muscle can be further broken down into three activation subdivisions in the sagittal plane and two activation subdivisions in the frontal plane. These activation subdivisions have been shown to fire separately based on the specific task performed (11,12). This unique and separate muscle subdivision activation of the gluteus maximus has been studied with various tasks being assessed by a laser-based mechanomyographic monitoring technique. It was measuring the mean contraction time in subdivisions of the muscle, both in the sagittal plane (superior, middle, inferior) and in the frontal plane (medial and lateral) (11,12).  These studies help us further understand how certain subdivisions of a large muscle can be functioning optimally in certain ranges of joint motion or during a specific part of a sports activity, and not in other ranges or parts. This helps shed light on the importance of the concept of vector specific muscle adaptations and training. It shows that certain portions of the same muscle can be functioning sub optimally at perhaps only one part of a sport specific motion, and that sometimes this depth of training specificity becomes vitally important if we want the whole muscle to work optimally, in order to best perform a high level integrated athletic movement. For Example, lets say a muscle may be working quite well with the hip in 90 degrees of hip flexion it does not mean that for the rest of the available range of motion it will continue to work optimally if it is never tested or trained in that range.

Other muscles which should be addressed and studied with this exercise are the quadriceps, gluteus medius and minimus, adductors, hamstrings, tensor fasciae latae, as well as any other muscles attached to the pelvis aiding in its stability and force generation such as the obliques, psoas, iliacus, deep and superficial lumbar extensors, and rectus abdominis. It is clear that this is a multifactorial exercise, which will activate many other muscles besides just the gluteus, so it is good to keep all of these anatomical connections in mind. Using anatomical kinematics it is easy to see how this exercise could correlate to sport specific improvements and could be favored by athletes of various professional and collegiate sports. It is important to also think of the vast clinical implications of this exercise as it will be shown to be a viable option for lower extremity strengthening, in the case that there are limitation such as: an athlete who has pain with end range hip flexion, pain and sensitivity with axially loading of the lower extremities, is on weight bearing precautions, has knee flexion extension limitations, or is for some reason unable to strengthen in an upright position. Versatility and creativity is a tool worth its weight in gold when rehabilitating injured high level athletes and this is another example of a creative way to strengthen and train which has been shown to have sport specific carryover, with comparable if not better muscular activation, than many traditional axially loaded closed chain lower extremity exercises.

EVALUATION

Let me start with a very important side note. Many studies currently use EMG (Electromyography) testing to analyze muscle activation during different exercises and movements. There are a few misconceptions with this. Electromyography measures the amplitude of electrical activity (the sum of the electric potential differences) of all of the active muscle motor units during a selected exercise that can be detected by the electrode placement. EMG cannot be said to solely measure motor unit recruitment as it measures motor unit recruitment combined with motor unit firing frequency. EMG does not directly measure force or force production, although some research shows a linear relationship between the two when the muscle being tested is not under fatigue. Another complication is that EMG activity will increase as it picks up on increased intracellular action potentials given off with increasing muscular fatigue that can be misconstrued as increased muscle activation. Thus EMG amplitude can be safely said to be an overall measurement of motor unit activity in the muscles required for each tested movement. This makes it most appropriately used to help the professional correctly choose the exercises that target the specific muscles we are trying to train or that are needed for each sport specific movement. Extrapolating that muscle EMG results lead to the selected muscle histological hypertrophy, specific strength, force production, or functional gains would be erroneous as further longitudinal research or research focused on these sport specific outcomes as variables would have to be used to back this thought. We are now seeing studies which combine both EMG testing and sport specific functional movement pre and post testing in order to correctly correlate sport specific adaption carryover attributed to different training modes.

The purpose of this first study, from 2015, was to compare the surface EMG activity of the upper and lower gluteus maximus, biceps femoris, and vastus lateralis between the back squat and barbell hip thrust, both dynamically and with a 3 second isometric hold. Thirteen trained women, mean age twenty-eight years old, performed an estimated 10-repetition maximums in the back squat and barbell hip thrust. The barbell hip thrust elicited significantly greater mean and peak upper gluteus maximus, lower gluteus maximus, and biceps femoris EMG activity than the back squat. There were no significant differences in mean or peak vastus lateralis EMG activity. Thus with this select population, the barbell hip thrust is a viable option for training the lower extremities which activates the gluteus maximus and biceps femoris to a greater degree than the back squat using an estimated 10RM load (6).

Furthermore, because the knee is flexed during the barbell hip thrust as the hip is driven into full extension it is theorized that the hamstrings are put into a position of active insufficiency, which would lead to a greater muscular effort requirement from gluteus maximus to generate sufficient hip extension torque. However other synergistic muscles such as the adductors could also produce this torque. Another study used EMG to show that when testing maximal isometric hip extension torque at 90°, 60°, 30°, and 0° hip flexion angles the gluteus maximus EMG activity is lowest with the hip in 90° of hip flexion and highest with the hip in 0° of hip flexion which would correlate more closely to the thrusters line of resistance and movement than that of a traditional squat (17).

Next, in 2016 a study focused on comparing the differences in upper and lower gluteus maximus, biceps femoris, and vastus lateralis EMG amplitude for the barbell, band, and American hip thrust variations. Again, thirteen healthy female subjects, mean age twenty-eight years old, performed 10 repetitions of their 10-repetition maximum of each variation in a counterbalanced and randomized order. The barbell hip thrust variation showed statistically greater mean gluteus maximus EMG amplitude than the American and band hip thrust variations, and statistically greater peak gluteus maximus EMG amplitude than the band hip thrust variation, but no other statistical differences were observed (5).

Now that we see that these EMG studies support the use of the barbell hip thrust to activates the gluteus maximus and other lower extremity muscles, the next question is does this correlate to functional sport improvements? A pilot study consisting of twenty-six participants, mean ages twenty-two years old, with an athletic background were recruited to participate in this study. The participants were divided into four groups, consisting of the back squat, deadlift , hip thrust, and control group. They took part in training three times weekly for a total of six weeks. This training followed a condensed linear periodization model consisting of a two-week emphasis on hypertrophy, two-week emphasis on strength, and a two-week emphasis on power and showed promise in functional gains (2). Then in 2016 a formal study compared the front squat to the barbell hip thrust by measuring the sport specific outcomes of vertical jump, horizontal jump, 10m sprint, 20m sprint, hip thrust, front squat, and isometric mid-thigh pull. The study consisted of twenty-four male rugby and rowing athletes, ages fourteen to seventeen years old, who were assigned to perform in the hip thrust or front squat group with workouts twice per week for 6 weeks, for a total of 12 sessions. The front squat and barbell hip thrust group results were broken down further into 8 effect size groups ranging from “Most unlikely” (<0.5%) to “Most likely” (>99.5%) effect size based on a 90% confidence limit in order to qualify the true effect size. The between-groups results are as follows; both the vertical jump and 3RM front squat “Possibly” (25-75%) favored the front squat group. The 10m and 20m sprint times “Possibly” (25-75%) favored the hip thrust group and it is “Unlikely” (5-25%) that one intervention was better than the other for improving the horizontal jump (3). When looking at the barbell hip thrust within-group effects as they correlate to the functional sport specific tasks it is shown that barbell hip thrust has a  “Very likely” (95-99.5%) beneficial effect for the 20-m sprint times and 3RM hip thrust strength and a “Possibly” (25-75%) beneficial effect for the 3RM front squat strength, vertical jump, horizontal jump, and 10-m sprint time (3).

Overall these studies indicate that the barbell hip thrust does activate gluteal muscles but athletes that participate in vertically based sports such as basketball and volleyball may benefit from the front squat more than the barbell hip thrust. However, in sports such as sprinting, football, and other low driving acceleration sports it may be more beneficial for athletes to perform the barbell hip thrust, because of its carryover into horizontal acceleration. Also, from this study the barbell hip thrust does seem to increase front squat and vertical jump performance when looking at pre and post testing. Thus the hip thrust is still a viable option to increase front squat and vertical jumping performance when squatting is contraindicated or just as an adjunct exercise to reduce axial load on the spine. These studies favor the theory that the direction of the resistance force vector relative to the body does play a large role in performance transference, and that axially resisted movements such as the squat appear to transfer better to vertically based sports, and anteroposterior resisted movements such as the barbell hip thrust appear to transfer better to horizontally based activities such as the 20-m sprint (3).

EXERCISE PROGRESSION

Let’s now walk through a possible progression for this exercise, but keep in mind this is very general and all training should be tailored to each individual’s sport function, athlete presentation, or stage of healing at the current time of training. Step one performing a subjective and objective evaluation, joint clearing, and other sport specific testing to make sure the lift is both sport specific, functional, and safe. Next, assess the athletes movement form without a bar, using a visual, verbal, and kinesthetic demo while simultaneously providing reasoning as to why certain body positions are important. Then progressing the athlete to a barbell hip thrust as shown in the accompanying video with this article and refer to the “Quick Look Movement” below for body positional cues and corrections. It may be pertinent at this point to correct movement faults and one of the most common is tibiofemoral adduction. To correct for this, especially with novice lifters, try the proprioceptive cue of an abduction band placed just above the knees. This has been shown in a 2017 squat study to aid untrained participants in the ability to achieve the muscle activation patterns required to promote neutral knee alignment and to resist medial collapse. In this study not only did this lead to neutral/correct tibiofemoral alignment but the addition of the band also increased gluteus max and gluteus medius muscle activity in the novice lifters and did not reduce the firing or change the form of the trained individuals (9). These phases may go fast but remember that this lower weight form is integral, as this lift will eventually be heavily loaded. If breakdown occurs with low weight, then it will most likely mean breakdown at higher weight, which may have larger negative consequences. Next, slowly add weight throughout the single or over multiple sessions. Starting weight can be based on the ease of the motion itself, squat, deadlift, or other lower extremity isometric and dynamic testing and measures.

Now this is where training may start to become very sport specific and goal oriented. Questions that should be asked might be are we looking to gain speed of contraction, to train around pain, to retrain muscles in new ranges of motion, or teach new motor patterns? These concepts and goals will dictate if we progress to using such aids as bands on the bar to train certain concepts of muscle adaptation, or add in training for ballistic speed, or start to add in upper extremity motions. Another concept is to train for differing lower extremity positions adding hip thrust with femoral abduction, adduction, internal, external rotation, and varying knee flexion angles based on sport specific lower extremity positional strength within safe kinematics and reason. This thought of training athletes in sport specific lower extremity positions which are not kinematically perfect but still safe is a slightly odd concept which should not be taken lightly as I do not think putting joints and athletes at risk for injury is wise when training. However, it would be false to think that an athlete who is stable and strong in a single idealized position would be stable in the  sport’s sometimes required unidealized body positions or movement patterns. Thus training towards these patterns or with differing lower extremity positions is not always a far off thought. Pushing the thought process up the chain, do we want to theoretically increase torsional stress on the trunk by performing the exercise single leg, with unstable hanging weights, with weight differences side to side, or on an unstable surface. Finally, I strongly believe after performing these strengthening exercises it is necessary to then put that newly activated muscle back into function. This laid out program is only one very brief version of what could possibly be done with each athlete and throughout this article it can be seen there are many benefits of the thrust movement if it is matched to the sport specific activity and trained with proper technique.

Some exercises to consider would be lumbar extension or side plank isometric holds on a roman chair at the gym with the hip pad positioned at different vertebral levels. Then we would progress this exercise by adding in a secondary component related to the sport such as the holds while catching a football, dribbling, shooting. Another exercise that is beneficial for trunk rotational faults would be side step outs without allowing trunk rotation while holding a weighted pulley or band with both upper extremities static at the navel level. You could also trial the static 45 degree hip flexion holds with a theraband around the thighs to promote posterior chain contribution and then add increased weight and lower extremity motions in all planes with the trunk held stable as shown in the accompanying video.

Side plank variations with the lower or upper extremity open chain limbs performing sports specific motions are also great functional exercises to perform that have been shown to maximize trunk activation at minimal spine load. Due to the high demand of some sports it may become important for the athlete to work on core stability with ipsilateral or contralateral lower and upper extremity open and closed chain functional patterns. If they are related to sport specific movements trial neutral spine association or dissociation with crawling, supine frozen bear rolling, bird dog, or dead bug type exercises with possible cable machine, free weight, or theraband resistance attached to upper or lower extremities.  

QUICK LOOK: MOVEMENT

• Back pad just below inferior border of scapula

• Padding on bar between bar and ASIS if needed

• Engage core using cues and proper bracing techniques prior to starting the lift

• Feet hips distance or slightly wider

• Knees in line with feet (No femoral adduction on hip drive (adductor dominance), can be cued with thigh band)

• Start with hip drive as hips push bar straight up

• Keep forward superior eye gaze

• Chin tuck sustained for entire motion (No cervical extension as you thrust up)

• No chest flair as you thrust upwards (Avoid TL junction irritation and hypermobility)

• Flat torso at top end position (Shoulders in line with the hip and knee)

• At the top end position maintain neutral spine (No anterior pelvic tilt/ lumbar spine lockout)

Exercise Progression:

• Hip thrust unweighted

• Hip thrust with abduction proprioceptive band unweighted

• Hip thrust with/without abduction band weighted

• Hip thrust with elastic bands for eccentric load/ Weight differences/ Unstable surface

• Hip thrust with single leg

Research Quick Reference:

• Young trained female athletes performing a 10RM barbell hip thrust both dynamically and isometrically will elicited significantly greater mean and peak upper gluteus maximus, lower gluteus maximus, and biceps femoris EMG activity when compared to a back squat. (Select muscle EMG activity greater with barbell hip thrust vs. squat)

• When testing maximal isometric hip extension torque at 90°, 60°, 30°, and 0° hip flexion angles the gluteus maximus EMG activity is lowest with the hip in 90° of hip flexion and highest with the hip in 0° of hip flexion which correlates more closely to the thrusters line of resistance vs a squat. (Isometric gluteus maximus EMG activity highest with the hip in full extension)

• When comparing the Barbell, Band, and American hip thrust variations with young trained female athletes performing a 10RM the barbell hip thrust variation showed greater mean gluteus maximus EMG amplitude than the American and Band hip thrust variations, and greater peak gluteus maximus EMG amplitude than the band hip thrust variation. (Pick thruster variations based on targeted EMG muscle activation)

• When comparing front squat vs. hip thrust training to the sport specific outcomes of vertical jump, horizontal jump, 10m sprint, 20m sprint, hip thrust, and front squat with young athletic males, the vertical jump and 3RM front squat showed greater results from the front squat trained group, and the 10m and 20m sprint times showed greater results form the hip thrust trained group, there was no between group difference in regards to horizontal jump. The hip thrust group showed improvements in the 20-m and 10-m sprint times, 3RM hip thrust strength, 3RM front squat strength, vertical jump, and horizontal jump. (Match training movements using the sport specific force vector theory for best carryover and hip thrust may be a viable alternative training method for conventional squats)

CITATIONS

1. Contreras, B, Cronin, JB, Schoenfeld, BJ, Nates, RJ, andSonmez, GT. Are all hip extension exercises Created equal? Strength Cond J 35: 17–22, 2013.

2. Worrell TW, Karst G, Adamczyk D, Moore R, Stanley C, Steimel B, et al. Influence of joint position on electromyographic and torque generation during maximal voluntary isometric contractions of the hamstrings and gluteus maximus muscles. J OrthopSport Phys Ther. 2001;31(12):730-740.

3. Wakahara T, Fukutani A, Kawakami Y, Yanai T. Nonuniform muscle hypertrophy: its relation to muscle activation in training session. Med Sci Sports Exerc. 2013;45(11):2158–2165.

4. Wakahara T, Miyamoto N, Sugisaki N, et al. Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training. Eur J Appl Physiol. 2012;112(4):1569–1576

5. Robertson, DGE, Wilson, JM, and St Pierre, TA. “Lower extremity muscle functions during full squats,” Journal of Applied Biomechanics, vol. 24, no. 4, pp. 333–339, 2008.

6. Morrissey, MC, Harman, EA, and Johnson, MJ. Resistance training modes: Specificity and effectiveness. Med Sci Sports Exerc 27: 648– 660, 1995.

7. McAndrew D, Gorelick M, Brown J. Muscles within muscles: a mechanomyographic analysis of muscle segment contractile properties within human gluteus maximus. J Musculoskelet Res. 2006;10(01):23– 35.

8. Lyons K, Perry J, Gronley JK, Barnes L, Antonelli D. Timing and relative intensity of hip extensor and abductor muscle action during level and stair ambulation. An EMG study. Phys Ther. 1983;63(10):1597– 1605.

9. Gullett, JC, Tillman, MD, Gutierrez, GM, and Chow, JW. A biomechanical comparison of back and front squats in healthy trained individuals. J Strength Cond Res 23: 284–292, 2008.

10. Foley, Ryan C.A. et al. “Effects of a band loop on lower extremity muscle activity and kinematics during the barbell squat.” International Journal of Sports Physical Therapy 12.4 (2017): 550–559. Print.

11. Contreras, Bret. Force Vector Training (FVT). The Glute Guy, 1 July 2010, Bretcontreras.com/load-vector-training-lvt/.

12. Contreras, B, Cronin, J, and Schoenfeld, B. Barbell hip thrust. Strength Cond J 33: 58–61, 2011.

13. Contreras, B, Vigotsky, AD, Schoenfeld, BJ, Beardsley, C, and Cronin, JA. Comparison of gluteus maximus, biceps femoris, and vastus lateralis EMG activity in the back squat and barbell hip thrust exercises. J Appl Biomech 31: 452–458, 2015.

14. Contreras, B, Vigotsky, AD, Schoenfeld, BJ, Beardsley, C, and Cronin, JA. A Comparison of Gluteus Maximus, Biceps Femoris, and Vastus Lateralis Electromyography Amplitude for the Barbell, Band, and American Hip Thrust Variations. Journal of Applied Biomechanics, 32, 254-260, 2016.

15. Contreras, B, Vigotsky, AD, Schoenfeld, BJ, Beardsley, C, and Cronin, JA. Comparison of gluteus maximus, Biceps Femoris, and Vastus Lateralis EMG amplitude in the parallel, full, and front squat variations in resistance trained females. J Appl Biomech 32: 16–22, 2016.

16. Contreras, B, Vigotsky, AD, Schoenfeld, BJ, Beardsley, C, McMaster, D, Reyneke, J, and Cronin, J. Effects if a six-week hip thrust Vs. Front Squat resistance training program on performance in adolescent males: A randomized controlled trial. Journal of Strength and Conditioning Research. 31(4)/999–100, 2016.

17. Contreras, B, Zweifel, MB, Vigotsky, AD, Njororai Simiyu, WW. Effects of 6-week squat, deadlift, or hip thrust training program on speed, power, agility, and strength in experienced lifters: A pilot study. Journal of Trainology 6:13-18, 2017.