Acute caffeine intake increases muscle oxygen saturation during a maximal incremental exercise test.
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2019
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British Journal of Clinical Pharmacology
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Abstract
Aims: The main mechanism behind caffeine’s ergogenicity lies in its
tendency to bind to adenosine A1 and A2A receptors. However, other
mechanisms might contribute to caffeine’s ergogenicity. The aim of this
investigation was to analyze the effects of caffeine on muscle oxygen
saturation during exercise of increasing intensity. Methods: Thirteen
healthy and active individuals volunteered to participate in a
randomized, double blind, placebo-controlled crossover trial. During two
different trials, participants either ingested a placebo (cellulose) or 3
mg/kg of caffeine. After waiting for 60 min to absorb the substances,
participants underwent a maximal ramp cycle ergometer test (25
W/min). Near infrared spectrometers were positioned on each leg’s
vastus lateralis to monitor tissue O2 saturation. Blood lactate
concentration was measured 1 min after the end of the exercise test.
Results: In comparison to the placebo, the ingestion of caffeine
improved the maximal wattage (258±50 vs 271±54 W, respectively, P <
0.001) and blood lactate concentration (11.9±3.8 vs 13.7±3.5 mmol/L,
P = 0.029) at the end of the test. Caffeine increased muscle oxygen
saturation at several exercise workloads with a main effect found in
respect to the placebo (F = 6.28, P = 0.029). Peak pulmonary
ventilation (124±29 vs 129±23 L/min, P=0.035) and VO2peak
(3.18±0.70 vs 3.33±0.88 L/min, P=0.032) were also increased with
caffeine. Conclusion: Acute ingestion of 3 mg/kg of caffeine improved
peak aerobic performance while caffeine-induced changes seen in muscle
oxygen saturation, pulmonary ventilation, and blood lactate
accumulation suggest that these mechanisms might also contribute to
caffeine’s ergogenic effect.
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Keywords
Near infrared spectroscopy, Muscle oxygenation, High intensity exercise, Cycling