Enhanced sarcoplasmic reticulum Ca(2+) release following intermittent sprint training.
To evaluate the effect of intermittent sprint training on sarcoplasmic reticulum (SR) function, nine young men performed a 5 wk high-intensity intermittent bicycle training, and six served as controls. SR function was evaluated from resting vastus lateralis muscle biopsies, before and after the training period. Intermittent sprint performance (ten 8-s all-out periods alternating with 32-s recovery) was enhanced 12% (P < 0.01) after training. The 5-wk sprint training induced a significantly higher (P < 0.05) peak rate of AgNO(3)-stimulated Ca(2+) release from 709 (range 560-877; before) to 774 (596-977) arbitrary units Ca(2+). g protein(-1). min(-1) (after). The relative SR density of functional ryanodine receptors (RyR) remained unchanged after training; there was, however, a 48% (P < 0.05) increase in total number of RyR. No significant differences in Ca(2+) uptake rate and Ca(2+)-ATPase capacity were observed following the training, despite that the relative density of Ca(2+)-ATPase isoforms SERCA1 and SERCA2 had increased 41% and 55%, respectively (P < 0.05). These data suggest that high-intensity training induces an enhanced peak SR Ca(2+) release, due to an enhanced total volume of SR, whereas SR Ca(2+) sequestration function is not altered.
Ortenblad
N
N
Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense University, 5230 Odense M, Denmark. niels.ortenblad@agrsci.dk
Lunde
P K
PK
Levin
K
K
Andersen
J L
JL
Pedersen
P K
PK
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000328:Adult; D001707:Biopsy, Needle; D002118:Calcium / Q000378:metabolism* / Q000493:pharmacokinetics; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology / Q000473:pathology; D018995:Myosin Heavy Chains / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010809:Physical Fitness; D020033:Protein Isoforms / Q000378:metabolism; D012433:Ryanodine / Q000493:pharmacokinetics; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
D007527:Isoenzymes; D020033:Protein Isoforms; D010725:Phosphocreatine; D012433:Ryanodine; D006003:Glycogen; D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains; D000252:Calcium-Transporting ATPases; D002118:Calcium