Relative Effort while Walking Is Higher among Women Who Are Obese, and Older Women

Abstract

Purpose Individuals who are obese, and older individuals, exhibit gait alterations that may result, in part, from walking with greater effort relative to their maximum strength capacity. The goal of this study was to investigate obesity-related and age-related differences in relative effort during gait. Methods Four groups of women completed the study, including 10 younger healthy-weight, 10 younger obese, 10 older healthy-weight, and 9 older obese women. The protocol included strength measurements at the hip, knee, and ankle in both flexion and extension, and gait trials under self-selected and constrained (1.5 m·s−1 gait speed and 0.65-m step length) conditions. Relative effort was calculated as the ratio of joint torques during gait, and strength from a subject-specific model that predicted strength as a function of joint angle. Results Relative effort during self-selected gait was higher among women who were obese in knee extension (P = 0.028) and ankle plantar flexion (P = 0.013). Although both joint torques and strength were higher among women who were obese, these increases in relative effort were attributed to greater obesity-related increases in joint torques than strength. Relative effort was also higher among older women in hip flexion (P < 0.001) and knee extension (P = 0.008), and attributed to age-related strength loss. Results were generally similar between self-selected and constrained gait, indicating the greater relative effort among women who were obese and older women was not attributed to differences in gait spatiotemporal characteristics. Conclusions Women who were obese, as well as older women, walk with greater relative effort. These results may help explain the compromised walking ability among these individuals.

The Effects of Power Training Frequency on Muscle Power and Functional Performance in Older Women: A Randomized Controlled Trial

“…All PT groups demonstrated either no change or a decrease in RPE for the training sessions (despite increases in 1RM and training load) and functional performance after training. Although there is an age-related increase in the relative force required to perform tasks (i.e., force required divided by maximum force capacity) (15,22), the increases in strength (1RM) in PT groups in this work would serve to reduce the relative force requirements for activities of daily living and might explain the decrease in perceived exertion after training. Hartman et al (13) found that in older adults, RT led to decreases in RPE during functional tasks as well as decreased oxygen cost for some of these functional tasks.…”

“…There were no differences in age, body mass, body mass index (BMI), and fat-free mass (FFM) between the groups at baseline (p 5 0.33-0.96); however, subjects in PT1 were significantly shorter compared with CON (p 5 0.03). On average, according to BMI (;26-27 kg•m 22 ) classification, subjects in each group were overweight, but there was large variation in BMI. After training, there were no differences within groups (p 5 0.13-0.97) or between groups (0.62-0.94, data not shown) for body mass, BMI, and FFM.…”