Skeletal muscle glycogen content and particle size of distinct subcellular localizations in the recovery period after a high-level soccer match.
Whole muscle glycogen levels remain low for a prolonged period following a soccer match. The present study was conducted to investigate how this relates to glycogen content and particle size in distinct subcellular localizations. Seven high-level male soccer players had a vastus lateralis muscle biopsy collected immediately after and 24, 48, 72 and 120 h after a competitive soccer match. Transmission electron microscopy was used to estimate the subcellular distribution of glycogen and individual particle size. During the first day of recovery, glycogen content increased by ~60% in all subcellular localizations, but during the subsequent second day of recovery glycogen content located within the myofibrils (Intramyofibrillar glycogen, a minor deposition constituting 10-15% of total glycogen) did not increase further compared with an increase in subsarcolemmal glycogen (-7 vs. +25%, respectively, P = 0.047). Conversely, from the second to the fifth day of recovery, glycogen content increased (53%) within the myofibrils compared to no change in subsarcolemmal or intermyofibrillar glycogen (P < 0.005). Independent of location, increment in particle size preceded increment in number of particles. Intriguingly, average particle size decreased; however, in the period from 3 to 5 days after the match. These findings suggest that glycogen storage in skeletal muscle is influenced by subcellular localization-specific mechanisms, which account for an increase in number of glycogen particles located within the myofibrils in the period from 2 to 5 days after the soccer match.
Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, 5230 Odense M, Denmark. jnielsen@health.sdu.dk
Joachim
J
Nielsen
Peter
P
Krustrup
Lars
L
Nybo
Thomas P
TP
Gunnarsson
Klavs
K
Madsen
Henrik Daa
HD
Schrøder
Jens
J
Bangsbo
Niels
N
Ortenblad
D006003:Glycogen / Q000032:analysis* / Q000737:chemistry / Q000648:ultrastructure*; D006801:Humans; D008297:Male; D046529:Microscopy, Electron, Transmission; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D009210:Myofibrils / Q000378:metabolism; D010316:Particle Size; D012916:Soccer / Q000502:physiology*
D006003:Glycogen