Fatigue resistance vs. fall resistance: high-intensity interval training and the dissociation of stamina and stability in older adults

Abstract

INTRODUCTION: The population of older adults (≥65 years) in the U.S. is growing, and this population faces unique health risks compared to young and middle aged adults. One of the primary health risks for older adults is falling, which is the leading cause of preventable death and injury within this population. Traditional exercise interventions have been effective in reducing fall risk but require significant time commitment. High-intensity interval training (HIIT) requires less time commitment than traditional exercise training and may be a viable alternative to reduce fall risk among older adults. METHODS: 13 sedentary young (n=7, 4 female; age: 21±1 (mean ± SE)) and older (n=6, 2 female; age; 69±2) adults completed 9 sessions of HIIT over 3 weeks. Balance at rest and after a single bout of HIIT was measured via center-of-pressure (COP) measures, fatigue resistance via a time to exhaustion (TTE) test, maximal aerobic capacity (VO2max) via indirect calorimetry and peak power output via Wingate test. All variables were assessed before and after training. RESULTS: Short-term HIIT had no effect on balance at rest or following a single bout of HIIT. TTE was greater in both young (25.8±4.0 vs. 37.0±3.1 min) and older (31.5±3.9 vs. 54.0±8.8 min) adults after training (p<0.05). VO2max was also greater after training (+1.8 ml/kg/min, p<0.05) in both groups. Peak power output during HIIT was greater after training in young (p<0.001) but not in older adults. CONCLUSION: These data do not support HIIT as an effective intervention for reducing fall risk in older adults. Three weeks of HIIT improves fatigue resistance but not balance, indicating a dissociation between stamina and stability in young and older adults.