Substrate utilization and work efficiency during submaximal exercise in vitamin C depleted-repleted adults

Carol Johnston, Pamela Swan, Corinne Corte

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


A placebo-controlled, depletion-repletion protocol was utilized to examine the effect of vitamin C status on substrate utilization during a 90 min walk at 50% maximal oxygen consumption (VO2max). Nine vitamin C depleted subjects (plasma vitamin C < 28 μmol/L) agreed to participate in the 5-week study (aged, 27.6 ± 2.5 years, mean ± SE; 5 females, 4 males). Subjects were apparently healthy but unaware of their vitamin C status. Prior to the experimental period, VO2max was measured using open-circuit spirometry during a graded walking protocol. Subjects ingested a placebo capsule daily during weeks 1-3 and a 500 mg vitamin C capsule daily during weeks 4-5 of the experimental study. Mean plasma vitamin C rose nearly 3-fold and mean plasma carnitine fell by nearly 20% at repletion (week 5) versus depletion (week 3). At the end of weeks 3 and 5, subjects completed a 90 minute treadmill walk at an exercise intensity of 50% VO(2max). The relative contribution of fat utilized for energy during walking did not differ in the vitamin C depleted versus repleted states. However, work performed by subjects and gross efficiency during exercise increased significantly at repletion versus depletion (10% and 15%, respectively). These data indicate that vitamin C depletion is associated with reduced work efficiency during submaximal exercise.

Original languageEnglish (US)
Pages (from-to)41-44
Number of pages4
JournalInternational Journal for Vitamin and Nutrition Research
Issue number1
StatePublished - Jan 1999


  • Exercise performance
  • Substrate utilization
  • Vitamin C status
  • Work efficiency

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Endocrinology, Diabetes and Metabolism
  • Nutrition and Dietetics


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