The Electromyography (EMG) calibration is used to detect which muscles are being activated during movements. In this case, we will look at the muscles being activated in the different angles of the squat. For starters, let’s talk about what muscles are involved in the squat: quads, hamstrings, and glutes (butt muscles). When studying the squat, the EMG feedback reveals the hip extensor muscles pattern (gluteus maximus, biceps femoris, and semitendinosus) EMG activity to be lowest in the early portion of the lift, increased in the middle portions and decreased at the end. The trunk muscle pattern (latissimus dorsi, abdominal obliques, rectus abdominis, and erector spinae) EMG activity, increased in the early portion of the lift, decreased in the middle parts and ended with a slight increase (Vakos et al., 1994). To specify the detail of the squat, the four portions of the lift were divided into quarters. This information identifies the muscles with the most activity, during the quarter squat phase (beginning and end), as muscles that are not required for joint movement in the hip and leg. The highest EMG activity was found in the middle portion, which would relate to the full squat position. Therefore, the majority power of the squat movement comes from the hip extensor muscles and these are the muscles that one needs to strengthen to increase vertical power and explosion.
Squat depth is a commonly debated topic. Benefits have been shown for quarter (120 degrees of knee flexion) and parallel, or full, squats. Hermassi, Chely, Tabka, Shephard, and Chamari (2011) published evidence that showed no changes in the jump performance of well trained power athletes after 24 weeks of heavy squat training, despite large improvements in a one rep max squat strength. They identified the use of loads that resemble the required skill in terms of movement, speed and pattern as the reason for improved jump performance (Hermassi et al., 2011). In general terms, shallow squats will make certain parts of your legs stronger, but since it is deeper than that of a jumping position, and not quite a full squat, it will not benefit explosive power.
Additional research supports the use of full squats, mainly due to the support of basic functional anatomy. Hartman et al. (2012) pointed out that deep joint angles provide neural and morphological stimuli for the hip and knee extensors to positively influence the acceleration process. Therefore, deep squats can help sustain dynamic maximal strength levels and should rarely be excluded from a strength training program (Hartman et al., 2012).
So how do we squat deep? It’s simple. Sit straight down and let your ankles, knees, and hips flex accordingly to their 100% ability. As you find yourself lowering, you may notice body position changes. You will know when to stop when you notice a position change and make corrections.
The above literature is simply to inform you about the absolute advantages to a “full range of motion” squat, versus anything less. Hopefully this will encourage you work on a deep squat rather than obsessing over a bigger squat number. A lighter weight deep squat will generate more work capacity throughout the mechanical chain than a heavier limited range of motion squat.
The above video has a part two, which takes you into an even deeper look at the anthropometric differences of squatters and their body differences. We as your coaches will help you squat properly, it is your job to squat regularly!
Hartman, H., Wirth, K., Klusemann, M., Dalic, J., Matuschek, C., & Schmidtbleicher, D. (2012). Influence of squatting depth on jumping performance. Journal of Strength and Conditioning Research, ahead of print, doe: 10.1519/JSC.0b013e31824ede62.
Hermassi, S., Chelly, M. S., Tabka, Z., Shephard, R. J., & Chamari, K. (2011). Effects of 8-week in-season upper and lower limb heavy resistance training on the peak power, throwing velocity, and sprint performance of elite male handball players. Journal of Strength and Conditioning Research, 25(9), 2424 – 2433.