by Bret Contreras August 09, 2016
Generating hypotheses is a fundamental aspect of scientific discovery. I encourage all of you to form your own hypotheses based on analyzing the biomechanics of the exercises and exploring the available literature (click HERE to read the Hip Thrust Wiki Page).
The “Lee Hamilton” study is going to be a very big deal in S&C. Either my predictions will pan out and the hip thrust will be catapulted to the top of the list of best glute exercises and most functional exercises, or the critics’ predictions will hold true and hip thrusts won’t lead to any improvements whatsover and can be kicked to the curb.
It is quite clear to me that the critics have poor knowledge of sports science and biomechanical instincts, but that’s why research is so important. Rather than call each other names, cherry-pick anecdotes, generate conspiracy theories, find fake experts to make outlandish claims, shift goalposts and demand impossible evidence, or warp logic to mold to preexisting biases, we can conduct randomized controlled trials and see what the data reveals, then update our knowledge base and form new theories.
We are going to move forward in conducting a huge training study (longitudinal/training studies are rare in S&C because they require much more time and effort than cross-sectional/mechanistic studies) that is going to provide much clarity as to how well the three most popular lower body exercises (squats, deadlifts, and hip thrusts) compare with each other in regards to their transfer to performance and ability to grow the glutes. When I say “we,” I mean Lee Hamilton and his team of researchers, as they’ll be conducting the study. But my team (yours truly, Chris Beardsley, Andrew Vigotsky, Brad Schoenfeld, and John Cronin) will provide input and of course funding. This post will seem intimidating to many individuals who don’t have a good grasp of sports science terminology, but I’ll try to make good sense of it at the end in the conclusion section.
In order to measure all of the variables of interest pre and post intervention (before and after the six weeks of training), Hamilton and colleagues will be utilizing this technology and collecting these data:
We’re going to obtain a tremendous amount of valuable data which will require a serious amount of time to properly analyze all of it.
Essentially, we’re going to take inexperienced lifters and subject them to 6 weeks of 3X/wk training. One group will just full squat, one will just hip thrust, and the other will just conventional deadlift. Volume will be matched and periodized, and progressive overload will be utilized.
Below, I will post my predictions based on my current knowledge of prior research, pilot data, and strength training and sports science. I encourage you to make predictions so that when the study is finally published down the road, you can check to see how savvy your biomechanical instincts were.
Gluteus Maximus Muscle Thickness Changes
Pennation Angle Changes
Fascicle Length Changes
Isometric Midthigh Pull Force Improvements
Horizontal Pushing Force Improvements
Maximum Speed Improvements
10 Meter Sprint Improvements
40 Yard Sprint Improvements
5-10-5 Agility Improvements
Vertical Jump Improvements
Horizontal Jump Improvements
Medball Rotational Scoop Toss Improvements
Isometric Hip Extension Torque at 90 deg Improvements
Isometric Hip Extension Torque at 0 deg Improvements
Squat Strength Improvements
Hip Thrust Strength Improvements
Deadlift Strength Improvements
I’m quite certain that I’ll be wrong on numerous predictions, but that’s what makes research fun – learning via hypothesis testing.
Let me be the first to say that squats and deadlifts are indeed “harder” to perform than hip thrusts. You can check my Instagram and see that I do heavy squats and deadlifts and hip thrusts week in and week out, and squats and deads require more psyching up and lead to greater overall muscle activation than hip thrusts. However, getting better at sports requires the preferential strengthening of some muscles and ranges of motion (ROM) over others. Hip thrusts don’t strengthen the quads like squats or the hams/traps/grip/thoracic erectors like deadlifts, nor do they work you quite as well down deep in the stretch position, but nevertheless they will transfer very well to performance. Hip extension strength through a full ROM is paramount in sports, and the hip thrust is superior for strengthening end-range hip extension strength. This is incredibly important and under-appreciated in S&C
I was fairly confident with certain predictions, especially strength predictions due to specificity. But I completely guessed on other predictions, for example rotational power (I could make a good case for all three exercises), midthigh pull (this will come down to deadlifts versus hip thrusts IMO), and horizontal jump (this will come down to deadlifts versus hip thrusts IMO).
I’ve picked hip thrusts to lead to the greatest levels of gluteus maximus mean and peak EMG amplitude and concentric force, velocity, and power, as well as the greatest changes or improvements in gluteus maximus muscle thickness and pennation angle, horizontal pushing force, 10m and 40yd sprint, maximum velocity, isometric hip extension strength at a neutral (0 degree) hip angle, and max hip thrust strength.
I’ve picked squats to lead to the greatest levels of eccentric force and barbell displacement, as well as the greatest changes or improvements in gluteus maximus fascicle length, 5-10-5 agility, and max squat strength.
I’ve picked deadlifts to lead to the greatest improvements in mid thigh pulling force, vertical and horizontal jump, medball rotational scoop toss, isometric hip extension strength at a flexed (90 degree) hip angle, and max deadlift strength.
Summary of hip thrusts
I believe that hip thrusts will require the greatest amounts of electrical output to the gluteus maximus (due to the interaction between the nature of the unique EMG activation angle curve inherent to the gluteus maximus [see Worrell et al.] and the unique nature of the torque angle curve inherent to the hip thrust exercise).
Due in large part to the superior EMG activation in addition to the tension and metabolic stress they produce, I believe that hip thrusts will lead to the biggest gains in hypertrophy. Since the hip thrust is hardest at the top of the motion when the glutes are shortened, they likely will not lead to any changes in muscle (fascicle) length, but pennation angle might increase slightly.
I believe that due to the mechanical efficiency of the hip thrust exercise, during the rising (concentric) phase, it will yield the highest outputs of force (mass times acceleration), velocity, and power (force times velocity). However, since individuals tend to just let gravity do its thing during the lower (eccentric) phase, the hip thrust will yield the lowest eccentric outputs in force. I believe that the hip thrust will also involve the shortest range of motion out of the three exercises.
I believe that due to the horizontal vector and torque angle curve inherent to the hip thrust, in addition to the superior glute activity and moderate hamstring activity, they will transfer best to sprinting and horizontal pushing force, and they’ll improve torque production the most at a neutral hip extension angle (end-range hip extension strength). Obviously they will maximize hip thrust strength due to the law of specificity, but they will also transfer better to squats than deadlifts and better to deadlifts than squats.
Summary of squats
Due to the interaction between the nature of the unique EMG activation angle curve inherent to the gluteus maximus [see Worrell et al.] and the unique nature of the torque angle curve inherent to the squat exercise, I believe that the squat will yield the lowest gluteus maximus EMG amplitudes. However, due to the muscle damage they produce in addition to moderate activation and tension, they will still produce good gains in gluteus maximus hypertrophy (just not as much as hip thrusts). And since squats are hardest down low in a stretched position (flexed-range hip extension), they will slightly lengthen the muscle fibers (increased fascicle length).
Since squats require a reversal from the eccentric to concentric phase in the air (hip thrusts and deadlifts can almost be dropped to the ground), they’ll lead to the highest levels of eccentric force (mass times acceleration during the lowering phase). Squats will utilize the greatest range of motion in terms of barbell displacement out of all three exercises.
Due to the knee extension demands and heavy eccentric/lowering component inherent to the squat, I believe that they will transfer best to agility. Due to specificity, squats will transfer best to squat strength.
Summary of deadlifts
Due to the movement specificity between deadlifts and vertical jumps, I believe that deadlifts will maximize vertical jumping ability. However, even though deadlifts are axial in nature, I believe that they’ll slightly outperform hip thrusts in horizontal jumping, due to the superior hamstring activation inherent to the deadlift. Even though deadlifts activate the hamstrings better than hip thrusts, I predict that hip thrusts will still be better for speed improvements due to the increased end-range hip extension demands.
I picked deadlifts to transfer best to isometric midthigh pull force due to the similarity in movement pattern, but hip thrusts will strengthen this test very well too due to the similarity in hip extension joint angle and torques. I also picked deadlifts to transfer best to rotational power (rotational medball scoop toss) since they utilize the glutes and the erectors very well and seem to involve more overall core activity, but I can see hip thrusts and squats leading to good improvements as well.
Deadlifts will transfer best to deadlifts in accordance with the law of specificity, and they’ll also improve isometric hip extension torque at 90 degrees (flexed range hip extension strength) to the greatest degree.
Most important, I predict that all three exercises are needed to help maximize performance in athletes. I can’t wait to see how it all pans out!
The post Squat vs. Hip Thrust vs. Deadlift Study Predictions appeared first on Bret Contreras.
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