Relationship between muscle strength and the time taken to complete a standardized walk-turn-walk test

We examined the effects of age and gender on the relationship between knee strength and walking time during a walk-turn-walk test in 176 male and 168 female generally healthy participants of the Baltimore Longitudinal Study of Aging who were aged 21-89 years. Subjects were timed as they walked 50 ft (15.24 m), turned around, and walked back to the starting point, both at a comfortable pace and as fast as possible. Isokinetic concentric knee extensor strength was measured at 30 degrees /s by using a Kin-Com dynamometer. Both comfortable and fast gait times increased with increasing age for both women and men, starting in middle age. An interaction was found between gender and age showing that older women are slower than older men at both paces. Gait time decreased linearly with increasing knee extensor strength, plateauing at higher strength levels (>130 N m for comfortable gait, and 190 N m for fast gait). Most women occupied the linear part of the curve below the plateau. Adjustment for body size, age, physical activity, and particularly number of steps to complete the task removed the relationship between strength and gait time for the comfortable gait. Women took longer to complete the walk-turn-walk test than men at older ages, were on the linear part of the strength-gait time relationship, and used more steps to complete the task, all of which may contribute to their greater likelihood of frailty in later years.