Before going any further it's important to identify that there are 2 different squat styles that are used : traditional and powerlifting. Both styles have their pros and cons and it's not necessarily down to body type or sport that dictates style. Traditional squat (high bar, shoulder width stance, upright trunk) is what's used in the majority of research and powerlifting style (wide stance, hip and back dominant) is still out for grabs for research from a biomechanical POV. So bare this in mind when reading evidence in this area surrounding WS. Also they use traditional squat style with feet straight which isn't commonly used in squatting.
So what is speculative about WS :
WS help you get depth
WS give you a stronger squat
Keep you more upright
Give you a stable base
In order to get a better idea of heel height influence you have to look at evidence around the ankle joint. Research looking at individuals with poor ankle mobility (reduced DF) has shown to impact on both lower limb and foot biomechanics and even a small increase of 10-17mm can impact on leg biomechanics on single leg squat and squat by reducing knee valgus and reducing hip flexion.
If you have flat feet / over pronation / navicular drop a small incline of 10mm has been shown to assist in improving you fore foot stability and you can further enhance this by arch supports. Flat feet has been shown to increase knee valgus in the squat as well as reducing knee flexion and increasing hip flexion.
Interestingly a 5 degree incline has shown to posteriorly displace the femoral condyles on the tib plateau in 20 degrees knee flexion which may further suggest that flat foot squat impacts on lower limb biomechanical changes may be down to biomechanical (convex-concave rule) changes in the knee.
Another point that has come across in literature particular to kinetic effects, the soleus works the hardest in both flat and heeled conditions in relation to gastroc with it soleus working harder in flat foot conditions. This suggesting that more emphasis In training should be put strengthening the soleus more than the gastroc to develop the squat. In addition a squat in heeled conditions can assist with reducing lateral talo crural activity and enable the gastroc to work equally further improving foot biomechanics and could assist in squat strength and power.
A high heeled squat can help with increasing quad activation but this has been shown in extreme heights of about 15cm. With regards to a solid sole and there is only one study that analysed this and demonstrated that firmer sole can help with minimising foot movement in the squat suggesting that a solid sole is important for safety and stability but doesn't improve squat power.
With all studies there is a mixture of methods for squatting with varying load, restricting aspects of the movement, squat speed, different heel heights, squat depth, foot position, bar position, different analysis equipment and different lab conditions so linking or comparing these studies is impossible making effects of WS still speculative at best.
So overall the evidence is still limited in is area but it definitely shows that subtle changes to the foot completely change squat biomechanics. WS or not, care should taken if you change your supportive equipment and ensure you graduate your training program.
Potentially Ideal for:
- maintaining a vertical shank on squt to prevent further stress to the ankle joint
- individuals with reduced ankle dorsi flexion
- can be helpful in treatment for patella tendinopathy
- shoulder width stance squat
- can assist with forefoot / flat foot issues
- help with increasing knee flexion
- front squat and single leg squat exercises
Potentially Not ideal for:
- Individuals patella tendinopathy
- wide squat stance or powerlift style squat
- novice lifters if they have full ankle mobility
- mobility events
- plyometric based activity
Hope that helps and any queries contact me.
Thank for reading.
(All images taken form google images)