Associations Between Women's Obesity Status and Diminished Cutaneous Sensibility Across Foot Sole Regions

People who are obese sustain very high foot pressures when standing, with potential consequences to their feet soles' cutaneous sensibility. In the current investigation, we performed a detailed assessment of foot sole sensibility in women with morbid obesity (n = 13; age = 38.85, SD = 8.09 years) status in comparison with leaner women (n = 13; age = 37.62, SD = 7.10 years). We estimated tactile feet sole sensibility through graduated monofilament light touch applied at several hotspots of both feet soles, covering the toes, metatarsal heads, midfoot internal and lateral arches, and heel. Intergroup comparisons per foot sole region indicated significantly lower sensibility for the group with morbid obesity under the fifth and third metatarsal heads, midfoot lateral and internal arches and heel. We found a large variation across the sole regions, with the lowest difference between the obese and lean groups observed under the hallux (18%) and the largest difference observed under the lateral arch of the midfoot (76%). Correlation analyses between body weight and sensibility scores revealed a significant positive correlation among participants who were leaner (r_s = 0.56, p = 0.05) but not among participants who were obese (r_s = -0.06, p = 0.83). Mainly, our results showed that morbid obesity was associated with significantly higher cutaneous sensibility thresholds, with large variability of the sensibility deficit across different regions of both feet soles. Due to its functional relevance for body balance control, reduced sensibility thresholds among women who are morbidly obese may have implications for stance stability.