A comparison of walking performance between individuals with and without asymptomatic peripheral artery disease using the six-minute walk test and the incremental shuttle walk test.

Objective: Two walking tests including the six-minute walk test (6MWT) and the incremental shuttle walk test (ISWT) are widely used to evaluate functional ability in individuals with disease conditions. However, it remains unclear whether these walking tests effectively manifest clinical impairment in individuals with asymptomatic peripheral artery disease (PAD). We aimed (i) to compare the walking performance of individuals with and without asymptomatic PAD using the 6MWT and ISWT, and (ii) to investigate the correlation between ankle-brachial index and toe-brachial index (ABI-TBI) and the walking distance.

Methods: A cross-sectional, crossover, matched pairs design was employed in this study. Asymptomatic PAD was diagnosed using ABI-TBI measurements. Seventy-six participants (38 with asymptomatic PAD and 38 without PAD) were randomly ordered to perform the walking tests. During the 6MWT, participants walked along the 30-meter corridor at their self-selected pace for six minutes, and the six-minute walk distance (6MWD) covered was recorded. In the ISWT, participants walked at a 12 prescribed speed level, and the incremental shuttle walk distance (ISWD) covered was recorded.

Results: Result revealed no difference in 6MWD between individuals with asymptomatic PAD and without PAD (mean distance: 501.6 m vs 516.8 m, p = 0.24). Asymptomatic PAD individuals exhibited a significantly shorter ISWD than those without PAD (median distance: 270 m vs 340 m, p = 0.003). No participants reported any leg pain symptoms during the 6MWT and ISWT. A statistically significant positive correlation was observed between the right leg TBI and ISWD in all participants (r = 0.23, p = 0.04).

Conclusions: Individuals with asymptomatic PAD demonstrated poorer walking performance than those without PAD when assessed using ISWT but not the 6MWT. Asymptomatic PAD is also associated with diminished walking performance during the ISWT. Thus, ISWT may show the clinical impairment in this population.