Razi Journal of Medical Sciences

Background: Effects of lower limb muscles fatigue on foot plantar distribution during walking has not been documented clearly in the literature. The purpose of this study was to determine the effect of quadriceps femoris muscle fatigue on alteration of the center of pressure and plantar pressure distribution during stance phase of walking.

Methods: Twenty-two males (age: 23.5±3.17 years, weight: 78.8±3.21 kg, height: 179.2±4.64 cm) participated in the study. Leg extension machine was used to induce quadriceps fatigue with 50% of one-repetition maximum. Peak plantar pressure distribution was collected using a foot scan pressure system during stance phase of walking. Paired t-test was used for data analyses.

 Results: Peak plantar pressure at the hallux first, third, fourth and fifth metatarsal bones and lateral part of heel was significantly increased (respectively: p=0.001, p=0.011, p=0.001, p=0.019, p=0.013, p=0.001), while peak pressure was decreased at the medial part of heel (p=0.001) and toes 2-5 area (p=0.001) after fatigue protocol. The center of pressure location was significantly shifted toward the lateral side of the foot (p=0.003) at contact phase, while it shifted toward the medial side at loading response phase (p=0.001) after fatigue. Conclusion: Results of this study showed that quadriceps muscle fatigue could increase foot plantar pressure characteristics, consequently influence pain and lower limb injuries.