Evaluation of optimal labor intensity with relative heart rate at plateau

Abstract

Objective To explore the law of the change of human heart rate under plateau environmental exercise load and establish an evaluation method of optimal labor intensity at plateau. Methods Sub-polar treadmill exercise test was used to measure the exercise heart rate and recovery heart rate of 228 subjects under different exercise load conditions at plain (altitude 300 m) and plateau (altitude 3 700, 4 200, 4 600 and 5 100 m). The maximum oxygen consumption (VO2max), heart rate change amplitude (X) and relative heart rate comprehensive index (Z) were calculated. Results Compared with the plain, VO2max of subjects from 3 700 m to 5 100 m at high altitude was decreased significantly (41.74±2.96, 41.25±2.84, 41.08±2.35, 41.60±2.82 vs 46.61±3.74 mL·kg-1·min-1, P < 0.05). The Z value of the relative heart rate comprehensive index was increases linearly with the increase of the X value of the heart rate change amplitude (Z=0.920+0.006X, R2=0.794). The Z value of moderate labor intensity (1.42±0.21) was obviously lower than that of severe labor intensity (1.52±0.23, P < 0.05). Conclusion Plateau environment significantly decreases the labor capacity of human body. So, the suitable labor intensity at plateau should be within the range of moderate labor intensity. Z=1.42 can be used as the cut-off value for judging moderate labor intensity in plateau environment.

Keywords

• relative heart rate
• plateau
• optimal labor intensity
• oxygen consumption
• exercise heart rate