Effect of Preexercise Meals with Different Glycemic Indices and Loads on Metabolic Responses and Endurance Running

Ya Jun Chen, Stephen H. Wong, Chun Kwok Wong, Ching Wan Lam, Ya Jun Huang, Parco M. Siu

Research output: Contribution to journalJournal articlepeer-review

36 Citations (Scopus)

Abstract

This study examined the effect of ingesting 3 isocaloric meals with different glycemic indices (GI) and glycemic loads (GL) 2 hr before exercise on metabolic responses and endurance running performance. Eight male runners completed 3 trials in a randomized order, separated by at least 7 days. Carbohydrate (CHO) content (%), GI, and GL were, respectively, 65%, 79, and 82 for the high-GI/high-GL meal (H-H); 65%, 40, and 42 for the low-GI/low-GL meal (L-L); and 36%, 78, and 44 for the high-GI/low-GL meal (H-L). Each trial consisted of a 1-hr run at 70% VO2max, followed by a 10-km performance run. Low-GL diets (H-L and L-L) were found to induce smaller metabolic changes during the postprandial period and during exercise, which were characterized by a lower CHO oxidation in the 2 trials (p < .05) and a concomitant, higher glycerol and free-fatty-acid concentration in the H-L trial (p < .05). There was no difference, however, in time to complete the preloaded 10-km performance run between trials. This suggests that the GL of the preexercise meal has an important role in determining subsequent metabolic responses.

Original languageEnglish
Pages (from-to)281-300
Number of pages20
JournalInternational Journal of Sport Nutrition and Exercise Metabolism
Volume18
Issue number3
DOIs
Publication statusPublished - Jun 2008
Externally publishedYes

Scopus Subject Areas

  • Medicine (miscellaneous)
  • Orthopedics and Sports Medicine
  • Nutrition and Dietetics

User-Defined Keywords

  • Carbohydrate
  • Glycemic index
  • Glycemic load
  • Preexercise diet

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