This study compared functional demand (FD) between older and younger women walking at habitual and fast speed and determined strength thresholds necessary to maintain FD below 80%. FD was calculated by expressing walking flexion and extension joint torques of the ankle, knee, and hip as a percentage of maximal strength. Young women had an average FD of 65% across joint actions and speeds, whereas older women had FD of 90%. In older women, the greatest FD occurred in the hip musculature. The hip, knee, and ankle extensor strengths required to maintain FD below 80% were 1.66, 1.86, and 0.57 Nm/kg, and flexor strengths were 1.24, 0.49, and 0.69 Nm/kg, respectively. Older women have limited functional reserve to increase gait speed and rely heavily on available hip strength during walking. This study identifies strength targets for the hip, knee, and ankle that will assist in maintaining FD of older women at a sustainable level.
Deborah Hebling Spinoso, Nise Ribeiro Marques, Dain Patrick LaRoche, Camilla Zamfollini Hallal, Aline Harumi Karuka, Fernanda Cristina Milanezi and Mauro Gonçalves
Mary Hellen Morcelli, Dain Patrick LaRoche, Luciano Fernandes Crozara, Nise Ribeiro Marques, Camilla Zamfolini Hallal, Mauro Gonçalves and Marcelo Tavella Navega
The aim was to compare torque and rate of torque development of lower limb muscles between older women with functional and slow gait speeds to determine which muscle group is the best predictor of functional gait speed, and to establish strength thresholds needed for functional walking speed. Torque and rate of torque development of hip, knee, and ankle muscles were measured in older women who were divided in 2 groups according to gait speed: slow gait speed (<1.22 m·s−1) and functional gait speed (≥1.22 m·s−1). For each muscle group, 3 maximal isometric contractions were performed, and peak torque and rate of torque development were recorded. Older women with slow gait speed had lower peak torque than older women with functional gait speed for hip extension (28%), knee flexion (15%), knee extension (14%), and plantar flexion (16%) (all Ps < .05). Older women with slow gait speed had lower peak rate of torque development for hip flexion (29%), hip extension (37%), knee flexion (34%), knee extension (33%), and plantar flexion (19%) (all Ps < .05). Knee extension peak rate of torque development and hip extension peak torque were the better predictors of functional gait speed with thresholds of 2.96 N·m·s−1·kg−1 and 1.26 N·m·kg−1, respectively.