Dissociation of training effects on skeletal muscle mitochondrial enzymes and myoglobin in man.
The effect of endurance training on skeletal muscle myoglobin concentration in man was investigated. 8 healthy sedentary males (20-31 yrs) trained on cycle ergometers 40 min/day, 4 days a week for 8 weeks. The work consisted of continuous exercise at a work load that during the last 5 weeks corresponded to 75% of the pretraining maximal oxygen uptake (VO2 max). The training program resulted in a 7% increase in VO2 max (p less than 0.01). The activities of the mitochondrial enzymes citrate synthase (CS), succinate dehydrogenase (SDH) and cytochrome c oxidase (Cyt-c-ox) in the quadriceps femoris muscle, as indicators of muscle respiratory capacity, increased by 62-82% (p less than 0.01). The metabolic adaptation of skeletal muscle was further indicated by a 17% increase in the work load corresponding to a blood lactate concentration of 4 mmol/l, as determined by a progressive exercise test (p less than 0.05). There was, however, no change in the myoglobin concentration of the thigh muscle with training (-1%, NS). It is suggested that endurance exercise in man at 75% of the maximal oxygen uptake does not severely tax the functions of myoglobin in skeletal muscle.
D000328:Adult; D002950:Citrate (si)-Synthase / Q000378:metabolism; D003578:Cytochrome-c Peroxidase / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism*; D006801:Humans; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009211:Myoglobin / Q000378:metabolism*; D010101:Oxygen Consumption; D010806:Physical Education and Training; D010807:Physical Endurance; D013385:Succinate Dehydrogenase / Q000378:metabolism
D004798:Enzymes; D009211:Myoglobin; D003578:Cytochrome-c Peroxidase; D013385:Succinate Dehydrogenase; D002950:Citrate (si)-Synthase