Biomechanics And Energetics Of Walking Uphill: A Better Form Of Exercise For Obese Adults?

Abstract

FigureBrisk walking is a recommended form of exercise for obese individuals. However, lower extremity joint loads and the associated risk of musculoskeletal injury or pathology increase with walking speed. Walking uphill at a slower speed may offer an alternative form of moderate intensity exercise that reduces joint loading. We hypothesized that compared to brisk walking, walking slower up a moderate incline would reduce lower extremity joint loading while providing appropriate physiologic stimulus. PURPOSE: To quantify the biomechanics and energetics of level and uphill walking in obese adults. METHODS: Ten obese adult volunteers, mass = 96.9 (13.5) kg, BMI = 33.5 (2.6) kg/m2, (mean (S.D.)), participated in this study. We measured ground reaction forces, three-dimensional lower extremity kinematics and oxygen consumption while subjects walked on a dual-belt force measuring treadmill at 1.75m/s (0°) and 0.75m/s (6°). We calculated net muscle moments at the hip, knee and ankle and metabolic rate for each condition. RESULTS: Walking slower uphill significantly reduced the peak knee extensor moment by 42% (64 vs. 37Nm) and the peak knee abduction moment by 31% (61 vs. 42Nm) compared to brisk, level walking. The greater knee moments during level walking suggests subjects had greater medial compartment knee joint loads. Metabolic rate was 25% greater during the level vs. uphill trials (6.3 vs. 5.0W/kg), but both walking trials were moderate intensity based on relative aerobic effort (65% vs. 53% of VO2max for level and uphill, respectively). CONCLUSIONS: A slower walking speed combined with a moderate incline appears to be an effective strategy for reducing knee joint loads while providing appropriate cardiovascular stimulus in obese adults.