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The Effect of Age and Training Status On Oxygen Uptake Kinetics In Women
We examined the effect of age and training status on the oxygen uptake (VO2) kinetics of untrained and recreationally trained women. Young (20–35yr), middle-age (40–55yr) and older (58–71yr) recreationally trained (YTR, n=10; MTR, n=12; OTR, n=9) and untrained (YUT, n=12; MUT, n=10; OUT, n=9) women participated in this crossectional study. Breath-by-breath VO2 and near-infrared-spectroscopy-derived (NIRS) muscle deoxygenation [HHb] were monitored continuously during increasing and constant walking exercises. On-transition VO2 and [HHb] responses to moderate intensity walking were modeled as mono-exponential. The data were normalized for each subject (0%–100%), and [HHb]/VO2 ratio was calculated as the average [HHb]/VO2 during the 20- to 120-s period after the onset of moderate intensity walking exercise. The time constant of VO2 (τVO2) was longer in OUT(23.8±2.4), MUT(25.4±5.1), YUT(23.1±3.4) than in YTR(16.2±2.0), MTR(16.7±3.9), OTR(16.3±2.8) women (p<0.05). The [HHb]/VO2 ratio in OUT (1.31±0.18) was higher than in YTR(1.08±0.05), MTR(1.13±0.09), YUT(1.12±0.09) (p<0.05). It is concluded that recreationally trained women had faster VO2 kinetics along with better matching of O2 delivery and utilization at the site of gas exchange in the exercising muscles.