Squat Stance, Grip Width, and Heel Height Effects on Patellofemoral Joint Loading During the Overhead Squat

Squat technique and heel elevation influence knee joint loading and patellofemoral mechanics, with important implications for rehabilitation, movement screening, and exercise prescription. However, no study has directly quantified these variables when comparing the Functional Movement Screen (FMS) overhead squat with an individual’s preferred stance and grip (PS) across different heel height conditions. Therefore, this study aimed to examine the FMS overhead squat by comparing knee joint loading and patellofemoral mechanics with a preferred squat stance. Ethical approval was granted by the University Ethics committee. Ten recreationally active participants (age: 22.9 ± 2.7 years; height: 179.7 ± 6.8 cm; mass: 79.5 ± 10.8 kg) performed overhead squats using both the FMS and PS techniques under five heel height conditions: flat-footed (0 cm), 1 cm, 2 cm, 3 cm heel wedges, and the FMS box (4.3 cm). Three-dimensional motion capture and force plate data were used to calculate mean peak patellofemoral joint stress (PFJS) and patellofemoral joint force (PFJF). Across all conditions, squat depth was controlled at 90° knee flexion using real-time motion capture feedback. Two-way repeated measures ANOVAs examined the effects of heel height and movement technique on PFJS and PFJF. PFJS showed no main effect of technique (F(1,9) = 0.82, p = .390), but a significant effect of heel height (F(1.72,15.46) = 29.53, p < .001), with PFJS increasing progressively with heel elevation; the interaction was not significant (p = .256). PFJF demonstrated a similar pattern, with no effect of technique (F(1,9) = 1.16, p = .309) but a significant effect of heel height (F(1.76,15.79) = 28.21, p < .001) and no interaction (p = .249). Post hoc analyses indicated significantly greater PFJS and PFJF in all elevated heel conditions compared with flat-footed, with the highest values observed in the box condition. A between-technique difference occurred only in the flat-footed condition, where PS produced greater PFJF than FMS (p = .022). The relatively small sample size may limit generalisability. Overall, heel elevation substantially increased patellofemoral joint loading, suggesting heel height may be a useful variable for progressing or regressing PFJS and PFJF during rehabilitation for patellofemoral pain syndrome.