Caffeine effects on VO₂ₘₐₓ test outcomes investigated by a placebo perceived-as-caffeine design
2017
Brietzke, Cayque | Asano, Ricardo Yukio | De Russi de Lima, Felipe | Pinheiro, Fabiano Aparecido | Franco-Alvarenga, | Ugrinowitsch, Carlos | Pires, Flávio Oliveira
Ergogenic effects of caffeine (CAF) ingestion have been observed in different cycling exercise modes, and have been associated with alterations in ratings of perceived exertion (RPE). However, there has been little investigation of maximal oxygen uptake (VO₂MAX) test outcomes. This study aimed to verify whether CAF may reduce RPE, thereby improving maximal incremental test (MIT) outcomes such as VO₂MAX, time to exhaustion and peak power output (WPEAK). Nine healthy individuals performed three MITs (25 W/min until exhaustion) in a random, counterbalanced fashion after ingestion of CAF, placebo perceived as caffeine (PLA), and no supplementation (baseline control). VO₂ was measured throughout the test, while RPE was rated according to overall and leg effort sensations. The power output corresponding to submaximal (RPE = 14 according to the 6–20 Borg scale) and maximal RPE was recorded for both overall (O-RPE₁₄ and O-RPEMAX) and leg RPE (L-RPE₁₄ and L-RPEMAX). VO₂MAX did not change significantly between MITs; however, CAF and PLA increased time to exhaustion (↑ ∼18.7% and ∼17.1%, respectively; p < .05) and WPEAK (↑ ∼13.0% and ∼11.8%, respectively; p < .05) when compared with control. When compared with control, CAF ingestion reduced submaximal and maximal overall and leg RPEs, the effect being greater in maximal (likely beneficial in O-RPEMAX and L-RPEMAX) than submaximal RPE (possibly beneficial in O-RPE₁₄ and L-RPE₁₄). Similar results were found when participants ingested PLA. Compared with control, CAF and PLA improved MIT performance outcomes such as time to exhaustion and WPEAK, without altering VO₂MAX values. CAF effects were attributed to placebo.
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