Relationship between quadriceps angle (Q) and plantar pressure distribution in football players

To determine whether there is an association between the Q-angle (Q) and the distribution of plantar pressure in football players, and to compare the characteristics of these athletes with non-practitioners of this sport.

121 male participants were selected: 50 football practitioners (FP) and 71 non-practitioners (NP). We concurrently evaluated the Q-angle and the plantar pressure through the software of postural assessment (SPA) and the F-Mat System, respectively. To verify the correlation between the Q-angle and peak pressure values in four segments of the foot (medial and lateral forefoot, medium-foot and hind-foot), the Pearson coefficient (r) for parametric analysis was used. The independent t-test was used to compare these variables between the groups. Data normality was verified by the skewness values, adopting a significance level of 5%.

A negative and weak correlation was found (r=-0.32) between the Q-angle and the plantar pressure in the right medium-foot. The groups differed with regards to the right Q-angle (11.36º in FP versus 13.80º in NP) and the left Q-angle (11.03º in FP versus 13.96º in NP). Plantar pressure was also different between the groups, with FP showing higher mean values for the right side and for the left side of the forefoot (0.77 kg/cm² in FP versus 0.63 kg/cm² in NP, and 0.65 kg/cm² in FP versus 0.54 kg/cm² in NP, respectively). However, mean peak pressure values for the left medium-foot were higher among NP (0.37 kg/cm² in FP versus 0.46 kg/cm² in NP).

There was no evidence of an association between the Q-angle and the distribution of plantar pressure in FP. The athletes showed reduced Q-angle values and higher mean peak pressure values for the right and left aspects of the forefoot, suggesting a varus malalignment and a supine distribution of plantar bases.