Hip thrust vs squat: which should you choose? For glute growth, a nine-week randomized trial found similar gains with either lift; squats produced more measured quadriceps and adductor growth, while each exercise improved its own three-repetition strength test most.
A six-week experiment with identical twins is an interesting case study, but its one person per exercise cannot settle the comparison for everyone. Read that story alongside the larger trial, your goal and the setup you can repeat comfortably.
The answer below starts with a goal-based choice, then checks what the MRI trial and the twins actually measured. It also explains why a larger first-session EMG signal did not reliably predict later glute growth.
Hip thrust vs squat: choose by goal
This table compares measured outcomes, not which exercise is universally superior. The strongest direct growth comparison here used untrained college-aged adults and equalized set volume, so a different program or trainee may respond differently.
| Your main goal or constraint | Reasonable first choice | What the evidence actually supports |
|---|---|---|
| Build glute size | Either lift, or both if they fit your program | The nine-week MRI trial found similar measured glute growth, with uncertainty around between-group differences. |
| Build quadriceps and adductor size too | Back squat | Those thigh regions grew more in the squat group in that trial. |
| Emphasize glutes while limiting added thigh work | Hip thrust may fit better | The hip-thrust group had less measured quadriceps and adductor growth in that nine-week protocol; this is not a body-shape guarantee. |
| Improve your back squat test | Practice squats | Squat three-repetition maximum gains favored squat training. |
| Improve your hip-thrust test | Practice hip thrusts | Hip-thrust three-repetition maximum gains favored hip-thrust training. |
| You dislike or cannot set up one lift comfortably | Use a tolerable variation and seek form help when needed | Neither exercise is mandatory; pain or an injury deserves individual assessment, not a blanket substitution rule. |
If your only reason to choose a hip thrust is that it feels more active in the glutes, the MRI result is a useful correction. A sensation or an electrical activation reading during one set does not rank long-term growth for every person.
How the six-week experiment worked
Contreras trained identical twin sisters who had exercised for years but had not previously followed progressive squat or hip-thrust programs.
One twin performed parallel back squats for the lower body; the other performed barbell hip thrusts. Each attended 18 sessions over six weeks.
The weekly plan used a medium day of four sets of 10 at roughly 75 percent of one-repetition maximum, a heavier day of five sets of six near 85 percent, and a lighter day of three sets of 15 near 65 percent.
The final set could continue for additional repetitions when possible. Both also performed comparable upper-body and abdominal work, with loads progressing week by week.
They were instructed to follow similar calorie and macronutrient plans, and their body weights changed little. Those details help interpret the comparison, but they do not make two separate people perfectly matched experimental units.
Even identical twins can differ in training history, technique, effort, recovery, and their response to a particular exercise. Neither was randomly assigned from a large group, and neither performed both programs in a crossover design.
That makes this a revealing small experiment, not a decisive trial of what everyone should do.
What happened to glute thickness
Contreras measured upper and lower gluteus maximus thickness with ultrasound. Thickness is one useful indicator of local muscle growth, though it is not the same thing as total muscle mass or a photograph of body shape.
In the 2015 preliminary blog report, the squat twin’s upper and lower measurements rose by about 20 and 21 percent. The hip-thrust twin’s two measurements were described as rising by about 28 percent each.
Those are the figures quoted in the accompanying Facebook post. They reflect what Contreras published at that stage of the project.
Both twins therefore improved during a short period of consistent, progressive training. The direction of the difference favored the hip thrust for the particular glute measurements reported here.
It would be a mistake to convert those within-person changes into a promise that a reader will gain 20 or 28 percent glute size in six weeks. The twins had a specific background and a coached, tightly structured plan.
Ultrasound thickness at two locations also cannot tell us everything about glute shape, leg-muscle growth, or long-term results beyond six weeks.
The useful result is not that one lift won forever. It is that both twins got stronger and both grew measurable glute thickness.
Why the reported percentages differ
The later doctoral-thesis abstract reports a different set of exact percentages for the same single-subject twin study.
It lists upper-glute thickness changes of 20.7 percent for the squat twin and 23.5 percent for the hip-thrust twin. For lower glutes, it gives 20.3 and 23.1 percent, respectively.
The thesis still reports increases with both lifts and a small advantage for the hip-thrust twin in those measured sites. But its 23-percent figures are not the 28-percent preliminary figures in the original blog.
The public abstract does not explain the full reason for that numerical change. It may reflect a later analysis or reporting revision, but that is an inference, not a fact we can establish from the abstract alone.
For that reason, we present both sets with their provenance rather than silently treating the earlier blog figures as final. Readers using the social post should know the 28-percent values came from Contreras’s preliminary report.
Neither set permits a meaningful population-level ranking from only two participants. A few percentage points between twins can be interesting, but it cannot substitute for a larger controlled study.
Strength and horizontal-force results
The squat twin increased her one-repetition back squat from 95 to 155 pounds. Her hip thrust also rose, from 225 to 265 pounds, despite not practicing it as her main lower-body lift.
The hip-thrust twin increased her squat from 95 to 135 pounds. Her hip thrust rose from 195 to 315 pounds.
These results illustrate specificity: the person practicing squats improved her squat more, while the person practicing hip thrusts improved her hip thrust much more.
They also show carryover in both directions. Training the hips and legs through one movement can improve another movement, especially when neither had been trained progressively in that way before.
Contreras additionally tested maximum horizontal pushing force using a force plate and a wall push. His preliminary report described an increase from 309 to 370 newtons for the squat twin and from 320 to 422 newtons for the hip-thrust twin.
Those changes correspond to roughly 20 and 32 percent, respectively, matching the social post’s summary. This is a specific laboratory-style push test, not a direct measurement of sprint speed or sports performance.
Although a hip thrust loads the hips differently from a squat, force direction alone does not determine transfer to every sport. Technique, speed, range of motion, and an athlete’s existing training all matter.
What the experiment cannot prove
One twin per condition means there is no way to estimate how much ordinary individual variation shaped the observed difference. The word “identical” does not solve that statistical problem.
The two programs also differed in how much total weight was moved and how long each set lasted. In the preliminary report, squat repetitions produced much more total time under tension, while hip thrusts accumulated a much greater volume load.
That means the comparison is not a perfectly isolated test of exercise name alone. It compares two real training approaches with several simultaneous differences.
The study did not establish that every person will grow more glute muscle from hip thrusts, that squats are inferior for total leg development, or that one lift replaces the other.
It did not measure quadriceps growth in the twins. Its horizontal-force test also should not be described as proof that hip thrusts always improve sprinting more than squats.
Six weeks is long enough to see changes in this pair, but not long enough to know which strategy performs better after months or years of training.
Contreras himself called for an adequately powered randomized trial. That caution belongs alongside the striking figures, not hidden at the bottom of the story.
What the nine-week MRI trial adds
In the 2023 Plotkin and colleagues study, 34 untrained college-aged participants were assigned to a back-squat group of 16 or a hip-thrust group of 18. They completed 15 to 17 supervised sessions over nine weeks with the number of training sets matched between groups.
MRI scans measured cross-sectional area at upper, middle and lower glute sites before and after training. Glute growth was similar on average, and the estimates modestly favoring hip thrusts had enough variance that the authors did not claim a clear glute winner.
Quadriceps and adductor growth was greater after squats. Strength gains favored the exercise participants practiced, while deadlift and wall-push test improvements were similar across groups.
During the first session, surface EMG was higher for the measured glute sites in the hip thrust. That electrical signal did not consistently predict which participants would show more MRI-measured glute growth nine weeks later, so activation alone cannot settle an exercise-selection argument.
How to read the study’s 2026 correction
A 2026 journal correction disclosed that BC Strength donated the hip-thrust apparatus and that two authors sell exercise-related products or services. It clarified that those authors helped design the study but did not recruit or train participants or collect or analyze data.
The correction also records that the trial was registered after its 2022 start and says the reported data and results are unchanged. These disclosures matter when weighing the evidence; the trial still involved untrained young adults, lasted nine weeks, and tested one main lift per group.
An earlier study of 22 well-trained women reported greater glute and quadriceps growth with back squats than hip thrusts under its own protocol. That difference reinforces the need to compare populations, methods and measures rather than claim that one experiment closes the subject.
How to use this evidence
The most direct nine-week trial did not show a clear glute-growth winner. It did find more thigh growth and larger squat-test gains in the squat group, while hip-thrust-test gains favored the hip-thrust group.
Those are group results from a specific protocol, not predictions for your body. To frame your own choice, write down the outcome you care about, which movement you can practice comfortably, and what lower-body work you already do.
Feeling one lift in the glutes more strongly is not proof it will grow them more. Likewise, the twins’ different percentages are a starting point for asking better questions, not a result to copy.
If both exercises fit your training, you do not have to treat them as opposing teams. A qualified strength coach can help select variations and an amount of work that match your goals and recovery, especially if technique or symptoms are a concern.
Compare like with like: measured muscle growth, which strength test improved, who was studied, and what the program involved. Avoid basing a training change on one EMG graph, a six-week pair of twins, or a claim that either lift is mandatory.
References
Plotkin, D. L., et al. (2023). Hip thrust and back squat training elicit similar gluteus muscle hypertrophy and transfer similarly to the deadlift. Frontiers in Physiology, 14, 1279170. https://doi.org/10.3389/fphys.2023.1279170
Plotkin, D. L., et al. (2026). Correction: Hip thrust and back squat training elicit similar gluteus muscle hypertrophy and transfer similarly to the deadlift. Frontiers in Physiology, 17, 1987823. https://doi.org/10.3389/fphys.2026.1987823
Barbalho, M., et al. (2020). Back squat vs. hip thrust resistance-training programs in well-trained women. PubMed record.
Contreras, B. (2015, August 10). Squats versus hip thrusts part II: The twin experiment. Bret Contreras. https://bretcontreras.com/squats-versus-hip-thrusts-part-ii-the-twin-experiment/
Contreras, B. (2015). Kinematics, kinetics, and electromyography of vertical and horizontal hip extension exercises and their transference to acceleration and power [Doctoral thesis, Auckland University of Technology]. AUT open repository.
Medical disclaimer: This article is general product information, not medical advice. The equipment described here is not a treatment for any condition. If you have an injury, ongoing pain, or a medical condition, talk to a doctor or physical therapist before using any of it.
