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Cardiorespiratory fitness in police recruits: Assessing the validity of the 20-meter shuttle run test for recruitment purposes.

BACKGROUND
Although the 20-meter shuttle run test (20MSR) is frequently used by police organisations for recruitment purposes, to our knowledge no study has yet assessed the accuracy of this test to estimate maximal oxygen consumption (VO2max) in police recruits.


OBJECTIVE
The primary objective of this study was to assess the validity of the 20MSR as a predictor of VO2max in police cadets.


METHODS
49 police cadets completed both an indirect calorimetry VO2max assessment and a 20MSR. Based on their results, estimated VO2max was calculated using an established equation. Furthermore, two models estimating the VO2max was also developed using the final stage completed and sex as independent variables in the first model (model A) as well as the final half-stage completed and sex in the second model (model B).


RESULTS
A strong and significant bivariate correlation was found between measured VO2max and the final stage completed at the 20MSR (r = 0.874, p <  0.001). Nevertheless, limits of agreement analysis showed relatively large agreement errors between measured VO2max and estimated VO2max based on the established equation (0.46±6.29 ml·min-1·kg-1), model A (0.00±5.58 ml min-1 kg-1), and model B (0.00±5.48 ml min-1·kg-1).


CONCLUSIONS
Although the 20MSR can be a useful tool to estimate cardiorespiratory fitness for research and conditioning purposes, the large agreement errors found in this study suggest that results at the 20MSR should be interpreted with cautious when making ''pass or fail" decisions.