Objective To assess the relationship among heart rate (HR), minute ventilation (VE), and oxygen uptake (VO2), and choose an optimal fitting function to find simple indicators for the evaluation of physical workload in plateau.
Methods Seventy-eight healthy males working at different altitudes were recruited in the study. An incremental cycle ergometer test until volitional fatigue was performed on all participants. Physiologic parameters, including VO2, VE, and HR, were recorded in a computerized test system. The optimal regression equation was chosen from fitting curves between VO2 and VE and between VO2 and HR.
Results Under the same physical workload and at varied altitudes, VO2 (P=0.505) and heart rate (P=0.306) did not show differences, but VE were significantly different (P < 0.001). At the same altitude and under varied physical workloads, VO2, HR, and VE were statistically different among the workers (P < 0.001). The optimal regression equation showed that the relationship between VE and VO2 (R2=0.903) was stronger than that between HR and VO2 (R2=0.583), which indicated that the power function of VE and VO2 was the best in data fitting. Further analysis found that VE under standard temperature and pressure, dry (VESTPD) was better fitted with VO2 than VE. The resulted fitting function was ŷVO2=0.06xVESTPD0.861, R2=0.930.
Conclusion VESTPD could replace VO2 to assess physical workload in plateau. The established function may supplement and improve existing national standard of physical workload.
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