Sprint training increases human skeletal muscle Na(+)-K(+)-ATPase concentration and improves K+ regulation.
This study investigated the effects of sprint training on muscle Na(+)-K(+)-adenosinetriphosphatase (ATPase) concentration, plasma [K+] regulation, muscle performance, and fatigue during severe intermittent exercise. Six untrained male subjects underwent intensive cycle-sprint training for 7 wk. Muscle biopsies were taken at rest from the vastus lateralis muscle before and after 7 wk of training and were assayed for Na(+)-K(+)-ATPase concentration using vanadate-facilitated [3H]ouabain binding to intact samples. Before and after the training period, subjects performed four maximal 30-s exercise bouts (EB) on a cycle ergometer, each separated by a 4-min recovery. Arterialized venous blood samples were drawn immediately before and after each sprint bout and were analyzed for plasma [K+]. The work output was significantly elevated (11%) across all four EBs after training. The muscle [3H]ouabain binding site concentration was significantly increased (16%) from 333 +/- 19 to 387 +/- 15 (SE) pmol/g wet wt after training but was unchanged in muscle obtained from three control subjects. Plasma [K+] rose by 1-2 mmol/l with each EB and declined rapidly by the end of each recovery period. The increases in plasma [K+] resulting from each EB were significantly lower (19%) after training. The ratios of rise in plasma [K+] relative to work output during each EB were also significantly lower (27%) after training. The increased muscle [3H]ouabain binding site concentration and the reduced ratio of rise in [K+] relative to work output with exercise are both consistent with improved plasma and skeletal muscle K+ regulation after sprint training.
Department of Physiology, University of Melbourne, Victoria, Australia.
M J
MJ
McKenna
T A
TA
Schmidt
M
M
Hargreaves
L
L
Cameron
S L
SL
Skinner
K
K
Kjeldsen
D000293:Adolescent; D000328:Adult; D001784:Blood Gas Analysis; D001835:Body Weight / Q000502:physiology; D005221:Fatigue / Q000503:physiopathology; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D009132:Muscles / Q000201:enzymology* / Q000502:physiology; D010042:Ouabain / Q000378:metabolism; D010806:Physical Education and Training; D005082:Physical Exertion / Q000502:physiology; D011188:Potassium / Q000097:blood / Q000502:physiology*; D011955:Receptors, Drug / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D006454:Hemoglobins; D011955:Receptors, Drug; C028996:cardiac glycoside receptors; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium