摘要：Wyatt FB, Donaldson A. Segmental Trend-Lines Define Heart Rate Response to Increased Work. JEPonline 2013;16(6):59-68. The purpose of this study was to establish mathematical regression trend lines for segmental changes in heart rate (HR) response to increased work in 10 male subjects with a mean (±SD) age of 29.6 ± 8.1 yrs. Pre-exercise testing included height (cm), weight (kg), age (yrs), percent body fat (%), and seated resting HR. The subjects were classified as fit given their mean (±SD) VO2 max of 70.3 ± 6.03 mL·kg-1 ·min-1 . Each subject began the bicycle ergometer test by pedalling at 150 watts (w) of work at a pedal rate of 80 to 90 rev·min-1 for the first 5 min followed by an increase in work of 25 w·min-1 until volitional fatigue. The following measurements were taken during the test: expired ventilation (VE), oxygen consumption (VO2), carbon dioxide (VCO2), and HR. Statistical analysis included the descriptive mean (±SD) of subjects and group test results, and the mean (±SD) values across subjects for HR at each measure. Statistical significance was set at P≤0.05. Segments of change for each phase were determined using logarithmic and linear regression analysis of group mean HR. Trend lines of best fit were used for each of the phases. Phase I indicates the withdrawal of the parasympathetic nervous system. Phase II indicates sympathetic influence, and Phase III indicates peripheral afferent signalling. Three phases accompany the subjects’ HR response during the incremental bicycle ergometer test. Each phase indicates an established physiological response of the subjects’ HR in a sequence of an initial rapid rise, a slower steady rise, and a final rise with a plateau from the onset of exercise to volitional fatigue.
