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

Screen Shot 2018-10-02 at 4.28.11 PM.png

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

Aasa U, et al. Br J Sports Med 2017;51:211–220. doi:10.1136/bjsports-2016-096037
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.
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.
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.
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.
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.
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.
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.
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
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
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.
McGill, Stuart. Ultimate Back Fitness and Performance Fourth Edition .Waterloo, Ontario Canada, 2009. Print. (P.73)
Rippetoe, Mark., and Lon Kilgore. Starting Strength: Basic Barbell Training.3rd ed. Wichita falls, Tx: Asagaard Co, 2011. Print.
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.
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.