The effects of two levels of caffeine ingestion on excess postexercise oxygen consumption in untrained women

Karen Donelly, Lars McNaughton

Research output: Contribution to journalArticle (journal)peer-review

29 Citations (Scopus)


The effects of two levels of caffeine ingestion (5, CAF1, and 10, CAF2) on postexercise oxygen consumption was investigated in six untrained women aged 20.5 (SEM 0.5) years. After a test to determine maximal oxygen consumption (VO2max) each subject underwent three test sessions at 55% VO2max either in a control condition (CON) or with the CAF1 or CAF2 dose of caffeine. During exercise, oxygen consumption was found to be significantly higher in the CAF1 and CAF2 trials, compared to CON (P <0.05). During the hour postexercise, oxygen consumption in CAF1 and CAF2 remained significantly higher than in CON (P <0.05). At all times throughout the exercise, free fatty acid (FFA) concentrations were significantly higher in the caffeine trials than in CON. The FFA concentrations 1h postexercise (+60 min) were further elevated above resting values for all three trials. Caffeine ingestion caused the greatest elevation above resting levels being 1.89 (SEM 0.19) mmol.l-1 and 1.96 (SEM 0.22) mmol.l-1 for the CAF1 and CAF2 trials, respectively. This was significantly higher (P <0.0001) than the CON level which was 0.97 (SEM 0.19) mmol.l-1. Respiratory exchange ratio (R) values became significantly lower (P <0.05) in CAF1 and CAF2 compared to CON at the onset of exercise and continued to decrease during the activity. Throughout the recovery period, R values were significantly lower for both caffeine trials compared to CON. The results of this study would suggest that caffeine is useful in significantly increasing metabolic rate above normal levels in untrained women during, as well as after, exercising at 55% VO2max
Original languageEnglish
Pages (from-to)459-463
Number of pages5
JournalEuropean Journal of Applied Physiology and Occupational Physiology
Issue number5
Publication statusPublished - Nov 1992


  • Caffeine
  • Excess postexercise oxygen consumption
  • Metabolic rate


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