The influence of South Asian ethnicity on the incremental shuttle walk test in UK adults

The objective of this study was to compare incremental shuttle walking test (ISWT) performance between South Asian and Caucasian British adults, identify predictors of ISWT distance and produce ethnicity-specific reference equations. Data from a mixed gender sample aged 40-75 years from Leicestershire, United Kingdom, were selected for analyses. Analysis of covariance determined differences in ISWT performance between South Asian and Caucasian British ethnic groups. Linear regressions identified predictors of ISWT distance, which determined the reference equations. In total, 144 participants took part in the study (79 South Asian (54 ± 8 years, 71% female) and 65 Caucasian British (58 ± 9 years, 74% female)). Distance walked for the ISWT was shorter for South Asian individuals compared with Caucasian British (451 ± 143 vs. 575 ± 180 m, p < 0.001). The ethnicity-specific reference equations for ISWT distance explained 33-50% of the variance (standard error of the estimate (SEE): 107-119 m) for South Asians and explained 14-58% of the variance (SEE: 121-169 m) for Caucasian British. Ethnicity univariately explained 12.9% of the variance in ISWT distance and was significantly associated with ISWT distance after controlling for age, gender, height, weight, dyspnoea and lung function ( B = -70.37; 1 = Caucasian British, 2 = South Asian), uniquely explaining 3.7% of the variance. Predicted values for ISWT performance were lower in South Asian people than in Caucasian British. Ethnicity-specific reference equations should account for this.