METABOLIC COST OF WALKING AT SET AND SELF-SELECTED SPEEDS IN OLDER MALES AND FEMALES

Abstract

PURPOSE To determine if self-selected (SS) walking speeds in older individuals are the most economical in terms of O2 consumption per distance walked (optimum walking speed) as it occurs in young adults and to assess any gender differences in metabolic cost and SS speed of walking. METHODS twenty six healthy older individuals (16 males, 10 females) volunteered for this study (mean age: 74 ± 3 yrs (range 70–82 yrs), height: 165.7 ± 8.2 cm, mass: 72.4 ± 11.3 kg, mean ± SD). Subjects walked on a level treadmill at 3, 4, 5 and 6 km.h−1 for 6 minutes at each speed. Following a rest period, the subjects walked for a further 6 minutes at their SS speed. This was achieved by using an ultrasound proximity sensor to adjust treadmill speed to that of the individual (Minetti, McKee, copyright MMU). The metabolic cost of walking (Cw: mlO2.(kg.km)−1) was calculated from the O2 consumption measured at steady state during the last 1–2 minutes of exercise at each speed (subtracting basal metabolic rate of quiet standing) and divided by the walking speed. Gender comparisons were made using repeated measures 2-way ANOVA. RESULTS The average SS speed was found to be 4.9 ± 0.1 km.h−1 (mean ± SE), with no significant difference observed between males (4.8 ± 0.2) and females (5.0 ± 0.2). The subjects' SS speed was found to be the most economical in terms of Cw (134.5 ± 3.9 mlO2.(kg.km)−1). The Cw at the SS speed was significantly lower than the Cw at 3 and 6 km.h−1 (174.4 ± 7.4 and 147.9 ± 4.3 respectively), but not significantly different to the Cw at 4 (140.7 ± 4.7) and 5 (138.7 ± 4.2) km.h−1. No significant differences were observed in the Cw between males and females at any speed. CONCLUSION The Cw in older individuals is optimum at their SS speed, independent of gender. In these individuals aged 70–82 yrs, the optimum speed of walking seems to be comprised between 4 and 5 km.h−1. Supported by European Commission Framework V funding (‘Better-Ageing’ Project, No QLRT-2001–00323)