Purpose: To critically appraise the utility of heart rate (HR) and power output (PO) to predict metabolic rate (MR) and oxygen consumption (VO2) during variable-intensity roller skiing and cycling. Methods: National-level cyclists (n = 8) and cross-country skiers (n = 9) completed a preliminary session to determine VO2max, and a variable-intensity protocol with 3 high-intensity stages at 90% VO2max for 3 minutes interspersed with 3 moderate-intensity stages at 70% VO2max for 6 minutes. Cardiorespiratory measures were recorded throughout. Linear HR-MR, HR-VO2, PO-MR, and PO-VO2 regressions were computed from the preliminary session, individually, for all athletes and used to predict MR and VO2 from both HR and PO, separately, during the variable-intensity protocol. Mean differences with 95% limits of agreement (LOA) between measured and predicted MR and VO2 were calculated. Results: MR and VO2 estimated from HR displayed a mean bias close to zero but wide LOA. HR overestimated MR and VO2 during moderate intensity but underestimated MR and VO2 during high intensity, for both roller skiing and cycling. MR and VO2 estimated from PO were more consistent across the experimental trial, displaying a mean bias farther from zero but with tighter LOA. Conclusions: This study has demonstrated that HR has limited utility to predict metabolic intensity during variable-intensity roller skiing and cycling because of wide LOA. On the other hand, metabolic intensity predicted from PO had tighter LOA, suggesting better consistency. PO might provide a better prediction of metabolic intensity compared with HR, particularly when longer-duration steps are performed during preliminary testing.
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