One Squat Fits All? Most Likely Not… but Allometric Scaling Might Compare Them All: An Exploratory Study

The squat exercise is one of the most widely practiced globally, prompting an investigation into the interplay among dimensional (particularly body height, BH), kinematic, and kinetic metrics. The study involved physically active men (n = 18, age: 23.8 ± 5 years, BH: 177.3 ± 10 cm, body mass: 78.1 ± 9 kg, body mass index: 24.9 ± 2.3 kg/m2, at least 6 months of squat training experience). They performed five squat repetitions (hands at midwaist) while being recorded with a Basler camera (100 Hz, sagittal plane) to estimate kinematic metrics (segmental inclination and joint angles at the lowest descending position), in synchronization with vertical ground reaction force and center of pressure recording (forceplate 1000 Hz, Kistler Type-9286AA, Bioware v. 5.5.1.0 software). Statistical analysis (SPSS 30.0, p ≤ 0.05) included one-way ANOVA to test the BH effect and allometric analysis to produce scaling exponents for the squat performance indices (Force, Leverage, and Stability Index) used to rank participants’ performance efficiency while neutralizing the influence of body size. The body-dimensional metrics differed significantly among the 3 BH groups, except for segmental proportions (p > 0.05). Apart from the more upright shank (about 6 degrees) in the Tall than in the Medium and Short BH groups (p < 0.05), no significant BH effect was observed in the kinematic and kinetic metrics (p > 0.05). Allometric scaling allowed us to rank participants’ performance across geometrically similar body sizes and underpinned the overall mechanical disadvantage of taller participants, as well as the role of the trunk-to-thigh body proportion in postural stability during squatting.