Plantar pressure changes after long-distance walking.

PURPOSE: The popularity of long-distance walking (LDW) has increased in the last decades. However, the effects of LDW on plantar pressure distribution and foot complaints, in particular, after several days of walking, have not been studied.
METHODS: We obtained the plantar pressure data of 62 subjects who had no history of foot complaints and who walked a total distance of 199.8 km for men (n = 30) and 161.5 km for women (n = 32) during four consecutive days. Plantar pressure was measured each day after the finish (posttests I–IV) and compared with the baseline plantar pressure data, which was obtained 1 or 2 d before the march (pretest). Mean, peak, and pressure–time integral per pixel as well as the center of pressure (COP) trajectory of each foot per measurement day were calculated using the normalization method of Keijsers et al. A paired t-test with an adjusted P value was used to detect significant differences between pretest and posttest.
RESULTS: Short-term adjustment to LDW resulted in a significant decreased loading on the toes accompanied with an increased loading on the metatarsal head III–V (P < 0.001). At all stages, particularly at later stages, there was significantly more heel loading (P < 0.001). Furthermore, the COP significantly displaced in the posterior direction but not in the mediolateral direction after marching. Contact time increased slightly from 638.5 +/- 24.2 to 675.4 +/- 22.5 ms (P < 0.001).
CONCLUSIONS: The increased heel loading and decreased function of the toes found after marching indicate a change of walking pattern with less roll-off. It is argued that these changes reflect the effect of fatigue of the lower leg muscles and to avoid loading of the most vulnerable parts of the foot.