Reliability of 400-m Walk Test Performance and Postexercise Cardiac Autonomic Markers in Older Women

The 400-m walk test (400MWT) is a useful tool to assess mobility and aerobic fitness, while postexercise heart rate recovery (HRR) and heart rate variability (HRV) are noninvasive tools for assessing cardiovascular health. However, measures of reliability, agreement, minimal detectable change (MDC), and coefficient of variation (CV) in older women with different levels of physical activity are lacking. This study aimed to evaluate measures of the reliability of the 400MWT and postexercise markers of cardiac autonomic control in active and sedentary older women. Eighteen physically active and 18 sedentary older women, performed the 400MWT twice, followed by measures of HRR at 1 (HRR1′) and 2 min (HRR2′), and HRV. Reliability was assessed by the intraclass correlation coefficient (ICC) and agreement by Bland–Altman plots. The standard error of measurement, CV, and MDC were calculated. The active group walked faster and completed the 400MWT in a shorter time than the sedentary group (all ps ≤ .03). In addition, in general, the active group presented higher HRR1′ and HRR2′ (all ps ≤ .04). 400MWT performance showed good reliability in both groups (ICC ≥ .78; all ps < .001; CVs ≤ 14% and MDC < 49 s). Indexes of cardiac autonomic control showed poor to good reliability (all ps < .001) with higher CVs than the 400MWT: HRV (ICC ≥ .39; CVs = 41.9%–97.6%; MDC = 12.1–31), HRR1′ (ICC ≥ .63; CVs = 36.2%–49.5%; MDC = 8.3–14.3 bpm), and HRR2′ (ICC ≥ .77; CVs = 33%–43.2%; MDC = 12.7–13.8 bpm). The 400MWT and HRR are reliable measures for the assessment of sedentary and physically active older women, but the reliability of HRV indexes varies according to the group.