Health-related criterion-referenced cut-points for cardiorespiratory fitness among youth: A systematic review

Background

Cardiorespiratory fitness (CRF), which reflects the overall aerobic capacity of the cardiovascular, respiratory, and muscular systems, is significantly related to health among youth.

Objective

The aim of this systematic review was to identify health-related criterion-referenced cut-points for CRF among youth aged 5–17 years.

Methods

A systematic search of two electronic databases (MEDLINE and SPORTDiscus) was conducted in September 2020. Only peer-reviewed studies that developed health-related criterion-referenced cut-points for CRF among youth were eligible provided they included (1) youth aged 5–17 years from the general population; (2) at least one quantitative assessment of CRF (e.g., peak oxygen uptake [VVO_2peak]); (3) at least one quantitative assessment of health (e.g., cardiometabolic risk); (4) a criterion for health; and (5) a quantitative analysis (e.g., receiver operating characteristic [ROC] curve) of at least one health-related cut-point for CRF. A narrative synthesis was used to describe the results of the included studies.

Results

Collectively, 29 included studies developed health-related criterion-referenced cut-points for CRF among 193,311 youth from 23 countries. CRF cut-points, expressed as VVO_2peak, estimated using the 20-m shuttle run test, demonstrated high discriminatory ability (median area under the curve [AUC] ≥ 0.71) for both cardiometabolic and obesity risk. Cut-points derived from maximal cycle-ergometer tests demonstrated moderate discriminatory ability (median AUC 0.64–0.70) for cardiometabolic risk, and low discriminatory ability for early subclinical atherosclerosis (median AUC 0.56–0.63). Cut-points for CRF using submaximal treadmill exercise testing demonstrated high discriminatory ability for cardiometabolic risk, but only moderate discriminatory ability for obesity risk. CRF cut-points estimated using submaximal step testing demonstrated high discriminatory ability for cardiometabolic risk and moderate discriminatory ability for high blood pressure, while those for the 9-min walk/run test demonstrated moderate-to-high discriminatory ability for obesity risk. Collectively, CRF cut-points, expressed as VVO_2peak, demonstrated moderate-to-high discriminatory ability (median AUC ≥ 0.64) for cardiometabolic risk, obesity risk, and high blood pressure.

Conclusions

Currently, there is too wide a range of health-related criterion-referenced cut-points for CRF among youth to suggest universal age- and sex-specific thresholds. To further inform the development of universal cut-points, there is a need for additional research, using standardized testing protocols and health-risk definitions, that examines health-related criterion-referenced cut-points for CRF that are age, sex, and culturally diverse.