Effects of a Long-Term Physical Activity Program on Activity Patterns in Mobility Impaired Older Adults

Abstract

PURPOSE: To examine the effect of a long-term structured physical activity intervention on accelerometer-derived metrics of activity composition changes in older adults at high risk for mobility disability. METHODS: Participants were randomized to either a physical activity (PA) or health education (HE) program. The PA intervention included a walking regimen with strength, flexibility, and balance training. The HE program featured health-related discussions and a brief upper body stretching routine. Participants (n = 1,341) wore a hip-worn accelerometer for ≥10 h/day for ≥3 days at baseline and again at 6, 12 and 24 months post-randomization. Total physical activity (TPA)—defined as movements registering 100+ counts/min—was segmented into the following intensities: low light (LLPA; 100-759 counts/min), high light (HLPA; 760-1,040 counts/min), low moderate (LMPA; 1,041-2,019 counts/min), and high moderate and greater (HMPA; 2,020+ counts/min) physical activity. Patterns of activity were characterized as bouts (defined as the consecutive minutes within an intensity). RESULTS: Both groups decreased TPA (-10.5±1.0 minutes/day annually), but the PA intervention attenuated this effect (PA vs HE: +6.4±2.1 minutes/day, p<0.001). This attenuation shifted TPA composition by increasing daily time in HLPA (1+ bouts: 0.8±0.3; 5+ bouts: 0.2±0.04; 10+ bouts: 0.1±0.02 minutes), LMPA (1+ bouts: 2.7±0.4; 2+ bouts: 2.4±0.3; 5+ bouts: 2.0±0.2; 10+ bouts: 1.1±0.1 minutes), and HMPA (1+ bouts: 2.8±0.4; 2+ bouts: 2.5±0.3; 5+ bouts: 2.1±0.3; 10+ bouts: 1.7±0.2 minutes). All findings were statistically significant at p<0.01. DISCUSSION: The PA intervention increased physical activity by shifting the composition of activity toward higher intensity activity in longer duration bouts. However, a long-term structured physical activity intervention did not completely eliminate overall declines in total daily activity experienced by mobility impaired older adults.