Physical activity and change in long distance corridor walk performance in the health, aging, and body composition study

Objectives To examine the prospective relationship between self-reported physical activity and aerobic fitness in the Health, Aging, and Body Composition Study (Health ABC) using the Long Distance Corridor Walk (LDCW). Design Cohort study with 7 years of follow-up. Setting Two U.S. clinical sites. Participants Community-dwelling older adults enrolled in Health ABC (N = 3,075, aged 70-79, 52% female, 42% black) with no self-reported difficulty walking one-quarter of a mile or climbing 10 steps. Measurements Participants were classified based on a physical activity questionnaire as being inactive (≤1,000 kcal/wk exercise activity, ≤2,719 kcal/wk total physical activity), lifestyle active (≤1,000 kcal/wk exercise activity, >2,719 kcal/wk total physical activity), or exercisers (≥1,000 kcal/wk exercise activity). The LDCW, an endurance walking test (400 m), was administered at Years 1 (baseline), 2, 4, 6, and 8 to assess aerobic fitness. Results At baseline, LDCW completion times (adjusted for age and sex) were 351.8 seconds (95% confidence interval (CI) = 346.9-356.8 seconds) for the inactive group, 335.9 seconds (95% CI = 332.7-339.1 seconds) for the lifestyle active group, and 307.7 seconds (95% CI = 303.2-312.3 seconds) for the exerciser group (P <.001). From baseline to Year 8, the inactive group slowed 36.1 seconds (95% CI = 28.4-43.8 seconds), the lifestyle active group slowed 38.1 seconds (95% CI = 33.6-42.4 seconds), and the exerciser group slowed 40.8 seconds (95% CI = 35.2-46.5 seconds), and did not differ significantly between groups. In linear mixed-effects models, the rate of change in LDCW time did not differ between the groups, although exercisers consistently had the fastest completion times (P <.001 for all pairwise comparisons). Conclusion Decline in LDCW time occurred regardless of baseline activity, although exercisers maintained higher aerobic fitness, which may delay reaching a critically low threshold of aerobic fitness at which independence is impaired.