Abstract
This study investigated whether the ingestion of a carbohydrate-electrolyte solution
during running would influence muscle glycogen utilisation in subjects who had consumed
a carbohydrate meal 3 hours before exercise. Eight men completed two 60-min treadmill
runs at 70 % V˙O2 max. Before each run they consumed a carbohydrate meal (183 ± 7g) 3 hours before exercise
and either 1) a carbohydrate-electrolyte solution during the run (46 ± 1g) (M+C),
or 2) water during the run (M + W). Biopsy samples were obtained from the vastus lateralis
muscle at rest and after 60 min of running. Serum insulin concentrations were higher
(p < 0.01) in both trials at the start of exercise compared with fasting values, whereas
blood glucose concentrations were higher (p < 0.01) after 60 min of running in the
M+C trial. Pre-exercise muscle glycogen concentrations were similar in both trials
(M+C: 321.9 ± 27.2 vs M+W: 338.8 ± 32.8 mmol × kg × dry weight-1 [dw]; NS). There was no difference in the amount of glycogen used during exercise
(M+C: 96.1 ± 22.1 vs M+W: 77.9 ± 11.7 mmol × kg × dw-1 ; NS). In conclusion, a carbohydrate-electrolyte solution ingested during treadmill
running at 70 % V˙O2 max does not influence muscle glycogen use during the first hour of exercise when
a carbohydrate meal is consumed 3 hours before exercise.
Key words
Pre-exercise meal - muscle glycogen - sports drink - running - glucose - insulin
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Prof. C. Williams
Department of Physical Education · Sports Science and Recreation Management · Loughborough
University
Loughborough · Leicestershire, LE11 3TU, · England · UK ·
Phone: +44 1509-228186
Fax: +44 1509-223970
Email: C.Williams@lboro.ac.uk