Body Mass and Foot-dominance Disparities in the Foot Plantar Pressure Parameters of Older Women.

Objectives: To examine the effects of foot dominance and body mass on foot plantar pressures in older women of regular, overweight, and obese weights.

Methods: 96 female adults were divided into regular-weight group (68.30 ± 4.19 yr), overweight group (69.88 ± 3.76 yr), and obesity group (68.47 ± 3.67 yr) based on their body mass index scores. Footscan® plantar pressure test system was used to assess the dynamic plantar pressures, and parameters were collected from risk analysis, foot axis analysis, single foot timing analysis, and pressure analysis.

Results: (1) The local risks of lateral forefoot and midfoot, the minimum and maximum subtalar joint angles, the flexibility of subtalar joint, foot flat phase, as well as the average pressures on toes, metatarsals,, midfoot, and lateral heel, with the peak pressures on toe 2-5, metatarsal 2, metatarsal 5, midfoot, and lateral heel had significant within-subject differences. (2) The phases of initial contact and foot flat, the average pressures on toe 2-5, metatarsals, midfoot, and heels, with the peak pressures on metatarsal 1-4, midfoot, and heels exhibited significant between-subjects differences. (3) There was an interaction effect of foot dominance and body mass index on the flexibility of subtalar joint.

Conclusions: The non-dominant foot works better for stability, especially when touching on and off the ground. The dominant foot works better for propulsion but is more susceptible to pain, injury, and falls. For obese older women, the forefoot and midfoot are primarily responsible for maintaining stability, but the lateral midfoot and hindfoot are more prone to pain and discomfort.