A simple method to derive speed for the endurance shuttle walk test.

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.