Babcock M A, Paterson D H, Cunningham D A, Dickinson J R
Centre for Activity and Ageing, University of Western Ontario, London, Canada.
Med Sci Sports Exerc. 1994 Apr;26(4):440-6.
The purpose was to characterize gas exchange kinetics following the on-transient of exercise in men aged 30-80 yr. Forty-six men completed square wave exercise tests from loadless cycling to subventilatory threshold (V(E)T) work rates with gas exchange measured breath-by-breath. Signal averaged data were fit with a monoexponential equation to derive time constants (tau) for gas exchange and ventilation (tau VO2, tau VCO2, tau VE) and heart rate (tau HR). There was a significant slowing of ventilation and gas exchange kinetics across age with linear regression yielding an increase of 0.67 s.yr-1 for tau VO2 (39 s in young to 61 s in old), 0.57 s.yr-1 for tau VCO2, and 0.65 s.yr-1 for tau VE, whereas tau HR (44 to 41 s) was not changed significantly. The slowed VO2 kinetics with age may reflect limitations in muscle blood flow or in control of the rate of oxidative metabolism. The less marked slowing of tau VCO2 compared with tau VO2 across age may reflect reduced CO2 storage capacity with loss of muscle tissue. The tau VE change across age was similar to that for tau VCO2 (tau VE/tau VCO2 unchanged). The present study demonstrated marked age-related slowing of gas exchange dynamics at exercise onset.
目的是描述30 - 80岁男性运动起始后气体交换动力学特征。46名男性完成了从无负荷骑行到低于通气阈值（V(E)T）工作强度的方波运动测试，逐次呼吸测量气体交换。对信号平均数据用单指数方程拟合，以得出气体交换和通气的时间常数（tau）以及心率的时间常数（tau VO2、tau VCO2、tau VE、tau HR）。随着年龄增长，通气和气体交换动力学显著减慢，线性回归得出tau VO2每年增加0.67秒（从年轻人的39秒增加到老年人的61秒），tau VCO2每年增加0.57秒，tau VE每年增加0.65秒，而tau HR（从44秒到41秒）无显著变化。随着年龄增长VO2动力学减慢可能反映了肌肉血流或氧化代谢速率控制方面的限制。与tau VO2相比，tau VCO2随年龄增长减慢程度较小，可能反映了随着肌肉组织丢失二氧化碳储存能力降低。tau VE随年龄的变化与tau VCO2相似（tau VE/tau VCO2不变）。本研究表明运动起始时气体交换动力学存在明显的年龄相关减慢。
