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Erschienen in:
18.08.2020 | Original Article
Estimating cardiorespiratory fitness from heart rates both during and after stepping exercise: a validated simple and safe procedure for step tests at worksites
Erschienen in: European Journal of Applied Physiology | Ausgabe 11/2020
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Purpose
Step test protocols are typically based on the heart rate (HR) measured either during exercise or during recovery. This study developed a new step test protocol to estimate maximal oxygen consumption (\(\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}\)) based on HRs measured during and after exercise, assessed the criterion validity of the model, and evaluated the protocol’s test–retest reliability.
Methods
The protocol estimates \(\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}\) from HR measurements made once a minute during 3 min of step exercise and 2 min of recovery. The model was derived using a group of 118 working adults and cross-validated using a second group of 74 working adults. Furthermore, \(\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}\) was measured using a conventional treadmill test. While multiple regression analyses were used to develop prediction equations for \(\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}\), intraclass correlation coefficients (ICCs) were used to examine test–retest reliability.
Results
HRs during and after exercise significantly correlated with the measured \(\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}\). The highest correlation (r = − 0.61) was for an HR index that combined values of HRs during and after exercise. A model including age, sex, body mass index, and the HR index accounted for 60% of the variance in measured \(\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}\) (standard error of the estimate, 4.05 mL kg−1 min−1 or 10.5%). Cross-validation analyses demonstrated good stability of the \(\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}\) prediction models. The ICC for the HR index was 0.65 (0.53–0.74), indicating fair to good reliability.
Conclusion
The HR index, based on a combination of HR measurements during and after stepping exercise, offers a validated \(\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}\) estimation procedure suitable for use in the workplace.