Adaptations in skeletal muscle following strength training.
Five men were studied before and after 7 wk of isokinetic strength training to determine its effects on muscle enzyme activities and fiber composition. One of the subject's legs was trained using 10 repeated 6-s maximal work bouts, while the other leg performed repeated 30-s maximal knee extension exercise. The total work accomplished by each leg was constant. Training 4 times/wk achieved similar gains in peak torque for both legs at the training velocity (3.14 rad/s) and at slower speeds. Fatigability of the knee extensor muscles, as measured by a 60-s exercise test, was similar in both legs after training. Biopsy specimens showed significant changes in the % of the muscle area composed of type I and IIa fibers as a result of both strength training programs. In terms of muscle enzymes, only the 30 s exercise program resulted in elevated glycolytic, ATP-CP and mitochondrial activities. Despite these changes, none of the parameters measured were found to be related to the gains in either muscle strength or fatigability during maximal isokinetic contractions.
D000222:Adaptation, Physiological; D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D003402:Creatine Kinase / Q000378:metabolism; D005221:Fatigue / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006019:Glycolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009119:Muscle Contraction; D009132:Muscles / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D005082:Physical Exertion
D000255:Adenosine Triphosphate; D006003:Glycogen; D003402:Creatine Kinase