title: Decreased resting levels of adenine nucleotides in human skeletal muscle after high-intensity training.
abstract: The effect of high-intensity intermittent training on the adenine nucleotide content of skeletal muscle was studied. Eleven male subjects (group A) performed high-intensity intermittent training on a cycle ergometer three times per week for 6 wk, followed by 1 wk of the same kind of training with two sessions per day. Nine males (group B) exclusively performed 1 wk of training with two sessions per day. In group A, skeletal muscle total adenine nucleotide (TAN) levels decreased from 25.1 +/- 0.7 (SE) to 22.0 +/- 0.6 mmol/kg dry wt over the 6-wk period (P < 0.01). The subsequent intensive week did not further alter TAN levels. In group B, the intensive week of training reduced TAN levels from 25.1 +/- 0.5 to 19.4 +/- 0.6 mmol/kg dry wt (P < 0.001). The decrease was sustained 72 h after training (P < 0.001). During the intensive week, there was no change in plasma creatine kinase activity in either group A or group B. The plasma activity was, however, higher in group B than in group A on days 4 and 7 of the intensive week (P < 0.05). The results from this study indicate that high-intensity intermittent exercise causes a decrease in resting levels of skeletal muscle adenine nucleotide without a concomitant indication of muscle damage. A training-induced adaptation appears to occur with training by which a further loss of adenine nucleotides is prevented despite an increased training dose.
authors.affiliation: Department of Physiology III, Karolinska Institute, Stockholm, Sweden.
authors.forename: Y
authors.initials: Y
authors.lastname: Hellsten-Westing
authors.forename: B
authors.initials: B
authors.lastname: Norman
authors.forename: P D
authors.initials: PD
authors.lastname: Balsom
authors.forename: B
authors.initials: B
authors.lastname: Sjödin
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D000328:Adult; D001642:Bicycling; D002851:Chromatography, High Pressure Liquid; D003401:Creatine / Q000097:blood; D003402:Creatine Kinase / Q000097:blood; D006801:Humans; D007042:Hypoxanthines / Q000097:blood; D007291:Inosine Monophosphate / Q000097:blood; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training; D011687:Purines / Q000097:blood; D014527:Uric Acid / Q000097:blood
chemical_list: D000227:Adenine Nucleotides; D007042:Hypoxanthines; D007773:Lactates; D011687:Purines; D007291:Inosine Monophosphate; D014527:Uric Acid; D019344:Lactic Acid; D003402:Creatine Kinase; D003401:Creatine