Coggan A R, Abduljalil A M, Swanson S C, Earle M S, Farris J W, Mendenhall L A, Robitaille P M
Exercise Physiology Laboratory, School of Health, Physical Education, and Recreation, Ohio State University, Columbus 43210.
J Appl Physiol (1985). 1993 Nov;75(5):2125-33. doi: 10.1152/jappl.1993.75.5.2125.
To examine effects of aging and endurance training on human muscle metabolism during exercise, 31P magnetic resonance spectroscopy was used to study the metabolic response to exercise in young (21-33 yr) and older (58-68 yr) untrained and endurance-trained men (n = 6/group). Subjects performed graded plantar flexion exercise with the right leg, with metabolic responses measured using a 31P surface coil placed over the lateral head of the gastrocnemius muscle. Muscle biopsy samples were also obtained for determination of citrate synthase activity. Rate of increase in P(i)-to-phosphocreatine ratio with increasing power output was greater (P < 0.01) in older untrained [0.058 +/- 0.022 (SD) W-1] and trained men (0.042 +/- 0.010 W-1) than in young untrained (0.038 +/- 0.017 W-1) and trained men (0.024 +/- 0.010 W-1). Plantar flexor muscle cross-sectional area and volume (determined using 1H magnetic resonance imaging) were 11-12% (P < 0.05) and 16-18% (P < 0.01) smaller, respectively, in older men. When corrected for this difference in muscle mass, age-related differences in metabolic response to exercise were reduced by approximately 50% but remained significant (P < 0.05). Citrate synthase activity was approximately 20% lower (P < 0.001) in older untrained and trained men than in corresponding young groups and was inversely related to P(i)-phosphocreatine slope (r = -0.63, P < 0.001). Age-related reductions in exercise capacity were associated with an altered muscle metabolic response to exercise, which appeared to be due to smaller muscle mass and lower muscle respiratory capacity of older subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
为研究衰老和耐力训练对运动期间人体肌肉代谢的影响，采用磷-31磁共振波谱法研究了年轻（21 - 33岁）和年长（58 - 68岁）未训练及耐力训练男性（每组n = 6）对运动的代谢反应。受试者用右腿进行分级跖屈运动，使用置于腓肠肌外侧头上方的磷-31表面线圈测量代谢反应。还获取了肌肉活检样本以测定柠檬酸合酶活性。随着功率输出增加，无机磷与磷酸肌酸比值的增加速率在年长未训练男性[0.058±0.022（标准差）W⁻¹]和训练男性（0.042±0.010 W⁻¹）中比年轻未训练男性（0.038±0.017 W⁻¹）和训练男性（0.024±0.010 W⁻¹）更大（P < 0.01）。年长男性的跖屈肌横截面积和体积（通过氢-1磁共振成像测定）分别小11 - 12%（P < 0.05）和16 - 18%（P < 0.01）。校正肌肉质量的这种差异后，与年龄相关的运动代谢反应差异减少了约50%，但仍显著（P < 0.05）。年长未训练和训练男性的柠檬酸合酶活性比相应年轻组低约20%（P < 0.001），且与无机磷-磷酸肌酸斜率呈负相关（r = -0.63，P < 0.001）。与年龄相关的运动能力下降与肌肉对运动的代谢反应改变有关，这似乎是由于年长受试者肌肉质量较小和肌肉呼吸能力较低所致。（摘要截短于250字）
