title: Role of submaximal exercise in promoting creatine and glycogen accumulation in human skeletal muscle.
abstract: We examined the effect of glycogen-depleting exercise on subsequent muscle total creatine (TCr) accumulation and glycogen resynthesis during postexercise periods when the diet was supplemented with carbohydrate (CHO) or creatine (Cr) + CHO. Fourteen subjects performed one-legged cycling exercise to exhaustion. Muscle biopsies were taken from the exhausted (Ex) and nonexhausted (Nex) limbs after exercise and after 6 h and 5 days of recovery, during which CHO (CHO group, n = 7) or Cr + CHO (Cr+CHO group, n = 7) supplements were ingested. Muscle TCr concentration ([TCr]) was unchanged in both groups 6 h after supplementation commenced but had increased in the Ex (P < 0.001) and Nex limbs (P < 0.05) of the Cr+CHO group after 5 days. Greater TCr accumulation was achieved in the Ex limbs (P < 0.01) of this group. Glycogen was increased above nonexercised concentrations in the Ex limbs of both groups after 5 days, with the concentration being greater in the Cr+CHO group (P = 0.06). Thus a single bout of exercise enhanced muscle Cr accumulation, and this effect was restricted to the exercised muscle. However, exercise also diminished CHO-mediated insulin release, which may have attenuated insulin-mediated muscle Cr accumulation. Ingesting Cr with CHO also augmented glycogen supercompensation in the exercised muscle.
authors.affiliation: School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham NG7 2UH, United Kingdom.
authors.forename: T M
authors.initials: TM
authors.lastname: Robinson
authors.forename: D A
authors.initials: DA
authors.lastname: Sewell
authors.forename: E
authors.initials: E
authors.lastname: Hultman
authors.forename: P L
authors.initials: PL
authors.lastname: Greenhaff
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis; D000328:Adult; D001786:Blood Glucose; D003401:Creatine / Q000378:metabolism*; D004032:Diet; D019587:Dietary Supplements; D015444:Exercise / Q000502:physiology*; D005260:Female; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010725:Phosphocreatine / Q000032:analysis; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D007328:Insulin; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D006003:Glycogen; D003401:Creatine