A simple method to derive speed for the endurance shuttle walk test
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BACKGROUND: The original method for determining endurance shuttle walk test (ESWT) speed involves components that are time consuming for clinicians. We sought to determine: (i) whether components described in the original method for determining ESWT speed held true and; (ii) the agreement between speeds derived using the original method and that equivalent to 85% of the peak speed achieved during the incremental shuttle walk test (ISWT). METHODS: Patients with chronic obstructive pulmonary disease (COPD) performed two ISWTs and one ESWT on separate days, wearing a calibrated portable gas analysis unit. A retrospective analysis of these data allowed us to determine whether: (i) the peak rate of oxygen uptake (V˙O₂peak) can be accurately estimated from the incremental shuttle walk distance (ISWD) and; (ii) ESWTs performed at a speed derived using the original method elicited 85% of V˙O₂peak. Agreement between walks speeds was determined using Bland-Altman analysis. RESULTS: Twenty-two participants (FEV₁ 48 ± 13% predicted, age 66 ± 8 yr) completed the study. The V˙O₂peak estimated from the ISWD was less than that measured during the ISWT (mean difference -4.4; 95% confidence interval (CI), -6.0 to -2.9 ml· kg⁻¹·min⁻¹). The ESWT and ISWT elicited similar V˙O₂peak (mean difference -0.2; 95% CI, -1.5 to 1.2 ml·kg⁻¹·min⁻¹). The mean difference (±limits of agreement) between ESWT speeds was 0.15 (±0.34) km·h⁻¹. CONCLUSIONS: Components of the original method for determining the ESWT speed did not hold true in our sample. ESWT speed can be derived by calculating 85% of the peak speed achieved during the ISWT.
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