Determining Squat Depth – Part 2

For this second part of looking at how to determine the ideal depth for squatting, we will look at how muscle activation changes during different squat methods. To look at general cues for squatting and why/when to use them, click here.

When trying to identify how muscle activation changes through different squat depths and relative loads, there are two methods commonly used to measure muscle contribution. There is Electromyography (EMG), which looks at the electric charge outputted from the muscle during contraction to determine when and how much it is working (Caterisano et al, 2002; Clark et al, 2012) . The second method is Net Joint Moment (NJM) which is commonly used to determine Relative Muscular Effort (RME) (Bryanton et al, 2012). NJM is Total Force generated at a specific joint segment, and RME is defined by Bryanton et al (2012) as the ratio of NJM during a specific task to the NJM of an isometric maximal voluntary contraction of that specific muscle (i.e. maximal knee extension exercise).

When researching this topic, it provided me with a fresh reminder of the nuances and the impressionable nature of interpreting research. Caterisano et al (2002) compared muscle activation in squat depth by utilising the same submaximal weight for a partial, parallel and a full squat. Through this, they concluded that as depth increased from partial to full squats, the Gluteus Maximus was the only muscle measured to have a significant increase in activation and quadriceps (vastus medialis) activation decreased with increased depths. Due to the constant weight used, they could not compare activation patterns with different loads.

Contrarily, Bryanton et al (2012) tested 50 – 90% loads for each individual for the back squat of a depth from 30 degrees (shallow) to 119 degrees (deep) of knee flexion (similar ranges to Caterisano et al, 2002). They determined that increased depth increases quadricep and hip extensor (Gluteus Maximus) (both work to straighten the leg) activation and increasing the load with shallower depth, increases ankle plantar flexor (think tip-toe movement) and hip extensor activation, as well.

The majority of research I read agreed with the findings of Bryanton et al (2012). Therefore, based on muscle activation, to determine your ideal squat depth, you must determine what kind of stimulus you are trying to achieve. As mentioned in the previous DPC blog post on Strength Training and Flexibility (can be found here), the SAID (Specific Adaptations to Imposed Demands) is directly relatable. Squatting more at a shallower depth will increase strength in that shallow range , ankle plantar flexor and hip extensor strength . Deeper range will provide a greater stimulus for the strength in that range as well, with more focus on the quadriceps along with the hip extensors (Bryanton et al, 2012).

In an attempt to further summarize an answer to how deep to squat based on muscle activation patterns, Clarke et al (2012) summarizes very well in saying “…stance, feet/hip rotation and depth should be dictated by the technical demands of squatting safely.” Squatting is very beneficial if done right and potentially hazardous if done wrong. Squat within your limits and not strictly for chasing numbers. The third and final Part will look at squat depth and how it relates to physical performances.