1. Changes in pulmonary oxygen uptake and muscle deoxygenation kinetics during cycling exercise in older women performing walking training for 12 weeks
- Author
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Kohji Hirakoba, Saburo Arima, and Akiko Hamasaki
- Subjects
medicine.medical_specialty ,Physiology ,Walking ,030204 cardiovascular system & hematology ,03 medical and health sciences ,0302 clinical medicine ,Oxygen Consumption ,Physiology (medical) ,Internal medicine ,Heart rate ,medicine ,Humans ,Orthopedics and Sports Medicine ,Deoxygenation ,Training period ,Aged ,Postmenopausal women ,Chemistry ,Pulmonary Gas Exchange ,Public Health, Environmental and Occupational Health ,VO2 max ,030229 sport sciences ,General Medicine ,Middle Aged ,Oxygen uptake ,Postmenopause ,Physical Fitness ,Cardiology ,Female ,Training program ,Cycling - Abstract
This study examined the hypothesis that walking training (WT) could accelerate the slowed time constant (τ) of phase II in pulmonary oxygen uptake ( $$\dot {V}$$ O2) on-kinetics in older women. Also, we aimed to demonstrate that O2 delivery and O2 utilization were better matched at the site of gas exchange in exercising muscles when τ $$\dot {V}$$ O2 was shortened. 20 recreationally active older women underwent WT sessions of approximately 60 min, 3–4 times a week for 12 weeks. We assessed $$\dot {V}$$ O2, heart rate (HR) and deoxygenated-hemoglobin concentration ([HHb]) kinetics during a constant-load exercise test before training (0 week—Pre), and at 6 and 12 weeks (6 weeks—Mid, 12 weeks—Post) throughout the training period. Maximal oxygen uptake ( $$\dot {V}$$ O2max) was unchanged throughout the training program. τHR tended to decline at Mid (58.6 ± 22.0 s), and was significantly shorter at Post (51.7 ± 21.7 s, p = 0.01) compared to Pre (67.1 ± 23.8 s). τ $$\dot {V}$$ O2 significantly decreased from 38.9 ± 8.6 s for Pre, to 31.5 ± 7.9 s for Mid (p = 0.02), and 32.3 ± 10.5 s for Post (p = 0.03). The normalized [HHb] to $$\dot {V}$$ O2 ratio (Δ[HHb]/Δ $$\dot {V}$$ O2) at Pre (1.32 ± 0.93) gradually approached the perfectly matched value (= 1.0) at Mid (1.15 ± 0.61) and Post (1.07 ± 0.52). The restoration to baseline (≒ 30 s) of the slower τ $$\dot {V}$$ O2 due to WT, which may reflect better matching of O2 delivery and O2 utilization at the site of gas exchange, suggests that a longer period of WT could be a useful tool for improving exercise tolerance in older individuals.
- Published
- 2017