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).
