Footwear outsole temperature may be more related to plantar pressure during a prolonged run than foot temperature

Abstract

Objective: The temperature of the sole of the foot has been suggested as an alternative to the measurement of plantar pressure during running despite the scarce evidence about their relationship. The temperature of the footwear outsole could also be representative of plantar pressure distribution due to its less multifactorial dependence. The aim of the study was to determine if plantar pressure during a prolonged run could be related to plantar temperature, either of the sole of the foot or the footwear outsole. Approach: Thirty recreational runners (15 males and 15 females) performed a 30-minute running test on a treadmill. Thermographic images of the sole of the foot and the footwear outsole were taken before and immediately after the test, and dynamic plantar pressure was measured at the end of the test. Pearson correlations and stepwise multiple linear regressions were performed. Main results: Plantar pressure percentage was related to a moderate correlation with plantar temperature percentage in forefoot and rearfoot (P<0.05), showing a greater relationship with the footwear outsole than with the sole of the foot (r=0.52-0.73 vs r=0.40-0.61, respectively). Moreover, moderate correlations were also observed between footwear outsole and sole of the foot temperature variables, especially in rearfoot. Significance: Footwear outsole temperature may be better related to plantar pressure distribution than sole of the foot temperature, in the forefoot and rearfoot. The midfoot is the most sensitive and variable region to analyze, as it does not seem to have any relationship with plantar pressure.