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Concentration of Triglycerides, Phospholipids and Glycogen in Skeletal Muscle and of Free Fatty Acids and β‐Hydroxybutyric Acid in Blood in Man in Response to Exercise
Author(s) -
Carlson Lars A.,
Göran Ekelund Lars-,
Fröberg Sven O.
Publication year - 1971
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/eci.1971.1.4.248
Subject(s) - glycogen , triglyceride , medicine , respiratory quotient , chemistry , endocrinology , fatty acid , skeletal muscle , biochemistry , biology , cholesterol
Twenty‐four fasting male subjects exercised until exhaustion on a bicycle at a relative workload of about 70% of the workload at heart rate 170 per min. Muscle tissue was obtained by needle biopsy from the lateral femoral muscle before and after exercise.—The average work time was 99 min. The muscle triglyceride concentration decreased during the exercise from 10.4 to 7.8 μmoles per gram and that of glycogen from 10.4 to 3.4 mg per gram. The concentration of phospholipids in the muscle remained unchanged.‐The amount of fatty acids and of glucose which were oxidized during the exercise was calculated from the oxygen uptake and the respiratory quotient and found to be 39 % and 61 % respectively of the caloric output. It was estimated that the muscle triglyceride and plasma free fatty acids (FFA) contributed about 2/3 and 1/3 respectively of the fatty acids oxidized. Similar calculations showed that muscle glycogen covered about 2/3 of the amount of glucose oxidized.—A number of correlation coefficients were calculated between the various parameters studied. There was no correlation between the triglyceride and glycogen content of the muscle. The amount of work performed was correlated to the glycogen ( r = 0.60) and to the triglyceride ( r = − 0.53) content of the muscle. These two muscle substrates could be used to predict the work performance by multiple linear regression analysis with an error of only 17 % and with a multiple correlation coefficient of 0.774.—The work performance was positively correlated to the amount of fatty acids oxidized but negatively correlated to the decrease in muscle triglycerides which suggests that the capacity to perform aerobic work is related to the utilization and mobilization of fatty acids from extramuscular sources.The obvious importance of local tissue stores of substrate such as glycogen and triglycerides for the energy metabolism was discussed.