Effect of long-term exercise on skeletal muscle lipid composition.

MORGAN, THOMAS E., FLOYD A. SHORT, AND LEONARD A. COBB. Effect uf hg-term exercise on skeletal muscle lipid compusihon. Am. J. Physiol. 216(l): 82-86. 1969.-The effect of 4-6 weeks unilateral isotonic quadriceps exercise on concentrations of total phospholipid, phosphatidyl choline, cholesterol, and triglyceride was studied in the trained and contralateral untrained vastus lateralis of 10 normal men. Phospholipid, phosphatidyl choline, and triglyceride concentrations were higher in trained resting muscle but cholesterol was lower. In each subject the phosphatidyl choline-to-cholesterol ratio was higher in the trained muscles. Cell fractions prepared from human muscle showed a high phosphatidyl choline-to-cholesterol ratio for mitochondria. The observed changes in phosphatidyl choline and cholesterol were compatible with increased mitochondrial size or number and decreased cell cholesterol. Triglyceride content was variable but was also consistently greater in trained muscle.