The current conventional wisdom among strength coaches seems to be that all clients and athletes should focus on a full range of motion (ROM) to promote superior strength and performance gains. While maintaining full ROM is obviously ideal, depending on the type of athlete you’re working with (and their specific goals), new research is shedding some light on how squat depth translates to performance gains.
A new study compared the effects of squat depth on vertical jump and sprint performance.(1) Twenty-eight college-aged male athletes were divided up and assigned to one of the three groups - full-squat, half squat and quarter squat - then performed a 16-week training protocol to assess the impacts on vertical jump and 40-yard sprint time. Interestingly, the greatest improvements in vertical jump and sprint time were found in the quarter-squat group (see Figure 1.0 and 2.0).
Figure 1.0 – Effect of Squat Depth on Vertical Jump
Figure 2.0 – Effect of Squat Depth on 40-Yard Sprint
Researchers believe that joint-angle specific changes to neuromuscular control may be the root cause of the improvements. Studies have found superior improvements in EMG in trained movements, versus those that are untrained.(2) Of course, the first quarter of the squat most closely resembles the hip and knee flexion ranges seen during jumping or sprinting, which is not surprising for most strength coaches. However, it’s interesting that in highly trained athletes, the load in the full squat seems ineffective for promoting gains in the quarter squat. In short, if you’re not doing quarter squats with your athletes who need to jump higher and run faster, you may be missing out on a piece to promote superior adaptation and performance. (However, it should be noted quarter squats also elicit greater anterior shear force that could predispose athletes to overuse injuries, if they’re not periodized appropriately.)
Depending on your athlete’s sport, the findings in this new study may be very impactful. Athletes with poor movement patterns or taller ectomorph-type athletes (i.e. basketball, volleyball, etc.) may benefit greatly from periods of training with quarter squats. If you’re performing deep squats with a basketball player, and using their 1-RM to base their training intensity, the work they perform at the quarter squat level will likely not be sufficient enough to overload the athlete and create positive adaptations. This new perspective of joint-angle overload suggests it’s not enough to simply train at different joint angles, you must overload the specific angle that applies specifically to your athlete’s sport (i.e. sprinting, jumping, etc.).
At the end of the day, quarter squats and full squats are very different; your neuromuscular system assesses and adapts to the stresses of varying squat depths differently. Therefore, it would make sense to incorporate more varied squat depth in your training protocols, just like the use of a variety of exercise to promote the greatest gains in strength and performance.
Dr. Marc Bubbs ND, CISSN, CSCS
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