Effects of muscle cooling on kinetics of pulmonary oxygen uptake and muscle deoxygenation at the onset of exercise. Issue 21 (31st October 2018)

• Record Type: Journal Article
• Authors: Wakabayashi, Hitoshi; Osawa, Mizuki; Koga, Shunsaku; Li, Ke; Sakaue, Hiroyuki; Sengoku, Yasuo; Takagi, Hideki
• Is Part Of: Physiological reports. Volume 6:Issue 21(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-10-31
• Subjects: Cold skeletal muscle -- glycolytic metabolism -- near‐infrared spectroscopy; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.13910
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: This study investigated effects of skeletal muscle cooling on the metabolic response and kinetics of pulmonary oxygen uptake ( V ˙ O2 ) and skeletal muscle deoxygenation during submaximal exercise. In the cooling condition (C), after immersion of the lower body into 12°C water for 30 min, eight healthy males performed 30‐min cycling exercise at the lactate threshold while undergoing thigh cooling by a water‐circulating pad. In the normal condition (N) as control, they conducted the same exercise protocol without cooling. Blood lactate concentration was significantly higher in C than N at 10 min after onset of exercise (4.0 ± 1.7 and 2.4 ± 1.2 mmol/L in C and N, P < 0.05). The percent change in the tissue oxygen saturation of the vastus lateralis, measured by a near‐infrared spectroscopy, was significantly lower in C at 2, 8, 10, and 20 min after the exercise onset compared with N ( P < 0.05). The percent change in deoxy hemoglobin+myoglobin concentration (Deoxy[Hb+Mb]) showed a transient peak at the onset of exercise and significantly higher value in C at 10, 20, and 30 min after the exercise onset ( P < 0.05). Compared to N, slower V ˙ O2 kinetics (mean response time) was observed in C (45.6 ± 7.8 and 36.1 ± 7.7 sec in C and N, P < 0.05). The mean response time in C relative to N was significantly correlated with the transient peak of Deoxy[Hb+Mb] in C ( r = 0.84, P < 0.05). These results suggest that lower oxygen delivery to the hypothermic skeletal muscle might induce greater glycolytic metabolism during exercise and slower V ˙ O2 kinetics at the onset of exercise. Abstract : This study investigated how muscle cooling affects the metabolism of the working muscle and pulmonary oxygen uptake kinetics at the onset of exercise. The major finding is that with muscle cooling the transient peak in muscle deoxygenation, reflecting less oxygen delivery relative to oxygen demand, is associated with slowing of oxygen uptake kinetics at the onset of exercise.