Criterion-related validity and reliability of the 2-km walk test and the 20-m shuttle run test in adults: The role of sex, age and physical activity level.

Objectives: To analyze the criterion-related validity and the reliability of fitness field tests for evaluating cardiorespiratory fitness in adults, by sex, age, and physical activity level.
Design: Cross-sectional.
Methods: During 3 weeks, sociodemographic, anthropometric measurements, a treadmill maximal test, the 2-km walk test, and the 20-m SRT were performed in 410 adults aged 18-64 years. Measured and estimated VO _2max (by Oja's and Leger's equations) were analyzed.
Results: Measured VO _2max was associated with estimated VO _2max by the 2-km walk test and 20-m SRT (r = 0.784 and r = 0.875, respectively; both p < 0.01). Bland-Altman analysis showed a mean difference of -0.30 ml* kg ^-1 * min ^-1 (p < 0.001, d = -0.141) in the 2-km walk test, and 0.86 ml* kg ^-1 * min ^-1 (p = 0.051) in the 20-m SRT. Significant mean differences between test and retest were found in the time to complete the 2-km walk test (-1.48 ± 0.51 s, p = 0.004, d = -0.014) and in the final stage reached in the 20-m SRT (0.04 ± 0.01, p = 0.002, d = 0.015). Non-significant differences were found between test and retest in the estimated VO _2max by Oja's (-0.29 ± 0.20 ml* kg ^-1 * min ^-1 , p > 0.05) and Leger's eqs. (0.03 ± 0.04 ml* kg ^-1 * min ^-1 , p > 0.05). Moreover, both test results and estimated VO _2max equations showed a high test-retest reliability.
Conclusions: Both tests were valid and reliable for evaluating cardiorespiratory fitness in adults aged 18-64 years, regardless of sex, age, and physical activity level.
Competing Interests: Declaration of interest statement The authors declare that they have no competing interests.
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