Human skeletal muscle adaptation in response to chronic low-frequency electrical stimulation.
The purpose of the study was to verify the influence of several weeks of chronic low-frequency electrical stimulation (LFES) on the metabolic profile and functional capacity of human skeletal muscle. Knee extensor muscles (KEM) of eight subjects were electrically stimulated at 8 Hz for 8 h/day and 6 days/wk. Vastus lateralis muscle samples were taken before, after 4 wk, and after 8 wk of LFES, and activities of anaerobic (creatine kinase, phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase) and aerobic-oxidative (citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, cytochrome-c oxidase) enzyme markers were determined. KEM dynamic performance was also assessed before, after 4 wk, and after 8 wk of LFES. Activity levels of anaerobic enzymes were not altered, whereas the activity levels of citrate synthase (29%),3-hydroxyacyl-CoA dehydrogenase (22%), and cytochrome-c oxidase (25%) were significantly increased after 4 wk of LFES but were not further increased after 4 additional wk of LFES. KEM performance was also improved (P < 0.05) but leveled off after 4 wk of LFES. Although significant changes were observed, the results of the present study suggest that the muscle characteristics investigated in the current study have a limited capacity of adaptation in response to this form of chronic LFES.
Thériault
R
R
Physical Activity Sciences Laboratory, Laval University, St Foy, Quebec, Canada.
Thériault
G
G
Simoneau
J A
JA
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism; D000222:Adaptation, Physiological / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000332:Aerobiosis; D000693:Anaerobiosis; D002950:Citrate (si)-Synthase / Q000378:metabolism; D003402:Creatine Kinase / Q000378:metabolism; D004558:Electric Stimulation; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006801:Humans; D007717:Knee; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000502:physiology; D010446:Peptide Fragments / Q000378:metabolism; D010732:Phosphofructokinase-1 / Q000378:metabolism
D010446:Peptide Fragments; C068142:glyceraldehyde 3-phosphate dehydrogenase (304-313); D015094:3-Hydroxyacyl CoA Dehydrogenases; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D003576:Electron Transport Complex IV; D002950:Citrate (si)-Synthase; D010732:Phosphofructokinase-1; D003402:Creatine Kinase