Effect of temperature on skeletal muscle energy turnover during dynamic knee-extensor exercise in humans.
The present study examined the effect of elevated temperature on muscle energy turnover during dynamic exercise. Nine male subjects performed 10 min of dynamic knee-extensor exercise at an intensity of 43 W (SD 10) and a frequency of 60 contractions per minute. Exercise was performed under normal (C) and elevated muscle temperature (HT) through passive heating. Thigh oxygen uptake (V(O2)) was determined from measurements of thigh blood flow and femoral arterial-venous differences for oxygen content. Anaerobic energy turnover was estimated from measurements of lactate release as well as muscle lactate accumulation and phosphocreatine utilization based on analysis of muscle biopsies obtained before and after each exercise. At the start of exercise, muscle temperature was 34.5 degrees C (SD 1.7) in C compared with 37.2 degrees C (SD 0.5) during HT (P < 0.05). Thigh V(O2) after 3 min was 0.52 l/min (SD 0.11) in C and 0.63 l/min (SD 0.13) in HT, and at the end of exercise it was 0.60 l/min (SD 0.14) and 0.61 l/min (SD 0.10) in C and HT, respectively (not significant). Total lactate release was the same between the two temperature conditions, as was muscle lactate accumulation and PCr utilization. Total ATP production (aerobic + anaerobic) was the same between each temperature condition [505.0 mmol/kg (SD 107.2) vs. 527.1 mmol/kg (SD 117.6); C and HT, respectively]. In conclusion, within the range of temperatures studied, passively increasing muscle temperature before exercise has no effect on muscle energy turnover during dynamic exercise.
Ferguson
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Copenhagen Muscle Research Centre, Institute of Exercise and Sport Sciences, August Krogh Institute, University of Copenhagen, Denmark. richard.ferguson@strath.ac.uk
Krustrup
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Kjaer
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Mohr
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Ball
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Bangsbo
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D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism; D000328:Adult; D001706:Biopsy; D001831:Body Temperature / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007773:Lactates / Q000032:analysis / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010725:Phosphocreatine / Q000032:analysis / Q000378:metabolism; D012039:Regional Blood Flow / Q000502:physiology; D013696:Temperature; D013848:Thigh / Q000098:blood supply / Q000502:physiology
D007773:Lactates; D010725:Phosphocreatine; D000255:Adenosine Triphosphate