Akiko Hamasaki1, Saburo Arima2, Kohji Hirakoba3. 1. Katsuura Orthopaedics Clinic, 485-252 Tona, Katsuura, Chiba, 299-5225, Japan. hamasaki@nanshuukai.com. 2. Katsuura Orthopaedics Clinic, 485-252 Tona, Katsuura, Chiba, 299-5225, Japan. 3. Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, Japan.
Abstract
PURPOSE: This study examined the hypothesis that walking training (WT) could accelerate the slowed time constant (τ) of phase II in pulmonary oxygen uptake ([Formula: see text]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[Formula: see text]O2 was shortened. METHODS: 20 recreationally active older women underwent WT sessions of approximately 60 min, 3-4 times a week for 12 weeks. We assessed [Formula: see text]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. RESULTS: Maximal oxygen uptake ([Formula: see text]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[Formula: see text]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 [Formula: see text]O2 ratio (Δ[HHb]/Δ[Formula: see text]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). CONCLUSIONS: The restoration to baseline (≒ 30 s) of the slower τ[Formula: see text]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.
PURPOSE: This study examined the hypothesis that walking training (WT) could accelerate the slowed time constant (τ) of phase II in pulmonary oxygen uptake ([Formula: see text]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[Formula: see text]O2 was shortened. METHODS: 20 recreationally active older women underwent WT sessions of approximately 60 min, 3-4 times a week for 12 weeks. We assessed [Formula: see text]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. RESULTS: Maximal oxygen uptake ([Formula: see text]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[Formula: see text]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 [Formula: see text]O2 ratio (Δ[HHb]/Δ[Formula: see text]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). CONCLUSIONS: The restoration to baseline (≒ 30 s) of the slower τ[Formula: see text]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.
Entities:
Keywords:
Aging; Maximal oxygen uptake; Near-infrared spectroscopy; Postmenopausal women; Time constant of oxygen uptake; Walking exercise
Authors: Juan M Murias; Matthew D Spencer; John M Kowalchuk; Donald H Paterson Journal: Am J Physiol Regul Integr Comp Physiol Date: 2011-04-13 Impact factor: 3.619
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