Dissociation of the ventilatory and lactate thresholds following caffeine ingestion.

Caffeine ingestion prior to the start of exercise has been shown to have an effect on ventilatory parameters and substrate utilization. Changes in either substrate utilization or ventilatory parameters may influence the determination of the lactate threshold (LT) and/or the ventilatory threshold (VT). Therefore, it was the purpose of this investigation to determine whether the VT and LT occur at similar metabolic rates and what effect caffeine ingestion will have on these two measures. Ten male subjects completed two maximal exercise bouts on the treadmill using a single blind procedure. One trial was performed 45 min after the ingestion of caffeine citrate (CC) in an amount equal to 7.0 mg of anhydrous caffeine.kg-1 body weight. The second trial was performed 45 min after the ingestion of a gelatin powdered placebo (P). Ventilatory parameters were monitored on a breath-by-breath basis, and blood for lactate determination was obtained from an antecubital vein every minute. Maximal oxygen consumption did not differ significantly between the CC (60.3 +/- 5.2 ml.kg-1.min-1) and P (59.7 +/- 5.6 ml.kg-1.min-1) trials. Oxygen consumption (VO2) values during the P trial at the VT (40.2 +/- 6.1 ml.kg-1.min-1) and the LT (38.6 +/- 3.3 ml.kg-1.min-1) were not significantly different (P less than 0.05). During the CC trial, VO2 values at the VT (44.4 +/- 6.6 ml.kg-1.min-1) and the LT (39.7 +/- 5.8 ml.kg-1.min-1) were significantly different. When comparing the VO2 at the LTs between the CC and P trials, there was no significant difference. There was, however, a significant difference in VO2 at the VTs when comparing the two trials. These data demonstrate a dissociation between the VT and LT following caffeine ingestion and suggest that the use of the VT as an indicator of the LT may be inappropriate following ingestion of moderate dosages of caffeine.
AuthorsM J Berry, J V Stoneman, A S Weyrich, B Burney
JournalMedicine and science in sports and exercise (Med Sci Sports Exerc) Vol. 23 Issue 4 Pg. 463-9 (Apr 1991) ISSN: 0195-9131 [Print] UNITED STATES
PMID2056905 (Publication Type: Clinical Trial, Controlled Clinical Trial, Journal Article)
Chemical References
  • Lactates
  • Lactic Acid
  • Caffeine
  • Adult
  • Breath Tests
  • Caffeine (pharmacology)
  • Energy Metabolism (drug effects)
  • Exercise (physiology)
  • Heart Rate (drug effects)
  • Humans
  • Lactates (blood)
  • Lactic Acid
  • Male
  • Oxygen Consumption (drug effects)
  • Respiration (drug effects)

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