Trial reportEuropean journal of applied physiology2026
Effects of caffeine and acute exercise on the validity of a submaximal cycle ergometer test: a randomised, placebo-controlled crossover study.
Trial report in European journal of applied physiology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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4 authors.
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Abstract
purposeTo investigate the effects of caffeine (Caf) consumption and prior exercise on the validity of the Ekblom-Bak cycle test (EB-test) for estimating maximal oxygen uptake (VO₂max).
methodsHealthy, habitual caffeine users received 250 mg Caf or placebo (Pla) in a double-blind randomised crossover design separated by one week. Each visit included two EB-tests performed before and after a maximal treadmill exercise (Ex). Heart rate (HR), blood pressure (BP), and oxygen uptake were measured, and estimation error was calculated as estimated-measured VO₂max. Data were analysed using repeated measures ANOVA with condition (Caf, Pla) and time (pre-Ex, post-Ex) as within-subject factors.
resultsParticipants were 15 women and 17 men (33.5 ± 11.1 years). Resting HR and BP did not differ between trials, except for a modest increase in systolic BP after Caf (129 ± 14 mmHg vs. 122 ± 15 mmHg; p = 0.042). Maximal HR and VO₂max were unaffected, but time to exhaustion increased with caffeine (438 ± 73 s vs. 415 ± 69 s; p = 0.012). HR increased significantly from pre- to post-Ex, with no differences between Caf and Pla conditions. Estimation errors rose from pre- to post-Ex (-0.17 and - 0.12 L·min⁻¹ to - 0.28 and - 0.30 L·min⁻¹), independent of caffeine intake, body mass, or measured VO₂max.
conclusionCaffeine did not affect the accuracy of the VO₂max estimation from the EB-test. However, strenuous exercise before testing increased estimation errors, suggesting that recent intense exercise has a greater impact on EB-test validity than moderate caffeine consumption.
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