Can we really influence the degree of muscle activation in different muscles of the lower body during varying depth squats?
There are a lot of variations in relation to the squat pattern:
- The foot position can be narrow or wide
- The feet can be orientated at different angles
- The bar can be positioned high on the scapula or low on the trapezius
- The orientation of the torso can be altered
- Bar speed can be changed
Not to mention the depth of the squat, which is often the most varied from one individual to the next.
Booth et al., (2002) examined the effect of 4 superficial hip and thigh muscles on squat depth – the researchers examined the EMG activity of the Vastus Medialis (VM), Vastus Lateralis (VL), Biceps Femurs (BF) and the Gluteus Maximus (GM). Each participant completed 3 squat sessions at varying depths:
- Partial (40 degree knee angle)
- Parallel (70-100 degree knee angle)
- Full Depth (greater than 100 degree knee angle)
The key finding of this particle study was that there was no significant difference in the muscle activity of VM, VL or the BF, however the study highlighted that during the concentric phase of the movement, GM activity was increased as squat depth increased. GM activity in relation to total muscle activity as a percentage can be seen below for each squat depth.
- Partial- 16.9%
- Parallel- 28%
- Full Depth- 35.4%
Although a common conception of many personal trainers is the greater activation of the hamstrings as squat depth increases this study would suggest otherwise. To create balance in the lower body, musculature specific hamstring training should be included. Furthermore clients that are unable to achieve full squat depth i.e. below parallel should focus their efforts on developing Glute strength and flexibility to achieve full depth during squat. The frequent utilisation of squats that are partial of parallel theoretically would create significant strength imbalances between the quadriceps and GM, potentially leading to injuries.