Caffeine Ingestion Increases Estimated Glycolytic Metabolism during Taekwondo Combat Simulation but Does Not Improve Performance or Parasympathetic Reactivation

Abstract

ObjectivesThe aim of this study was to evaluate the effect of caffeine ingestion on performance and estimated energy system contribution during simulated taekwondo combat and on post-exercise parasympathetic reactivation.MethodsTen taekwondo athletes completed two experimental sessions separated by at least 48 hours. Athletes consumed a capsule containing either caffeine (5 mg∙kg-1) or placebo (cellulose) one hour before the combat simulation (3 rounds of 2 min separated by 1 min passive recovery), in a double-blind, randomized, repeated-measures crossover design. All simulated combat was filmed to quantify the time spent fighting in each round. Lactate concentration and rating of perceived exertion were measured before and after each round, while heart rate (HR) and the estimated contribution of the oxidative (WAER), ATP-PCr (WPCR), and glycolytic (W[La-]) systems were calculated during the combat simulation. Furthermore, parasympathetic reactivation after the combat simulation was evaluated through 1) taking absolute difference between the final HR observed at the end of third round and the HR recorded 60-s after (HRR60s), 2) taking the time constant of HR decay obtained by fitting the 6-min post-exercise HRR into a first-order exponential decay curve (HRRτ), or by 3) analyzing the first 30-s via logarithmic regression analysis (T30).ResultsCaffeine ingestion increased estimated glycolytic energy contribution in relation to placebo (12.5 ± 1.7 kJ and 8.9 ± 1.2 kJ, P = 0.04). However, caffeine did not improve performance as measured by attack number (CAF: 26. 7 ± 1.9; PLA: 27.3 ± 2.1, P = 0.48) or attack time (CAF: 33.8 ± 1.9 s; PLA: 36.6 ± 4.5 s, P = 0.58). Similarly, RPE (CAF: 11.7 ± 0.4 a.u.; PLA: 11.5 ± 0.3 a.u., P = 0.62), HR (CAF: 170 ± 3.5 bpm; PLA: 174.2 bpm, P = 0.12), oxidative (CAF: 109.3 ± 4.5 kJ; PLA: 107.9 kJ, P = 0.61) and ATP-PCr energy contributions (CAF: 45.3 ± 3.4 kJ; PLA: 46.8 ± 3.6 kJ, P = 0.72) during the combat simulation were unaffected. Furthermore, T30 (CAF: 869.1 ± 323.2 s; PLA: 735.5 ± 232.2 s, P = 0.58), HRR60s (CAF: 34 ± 8 bpm; PLA: 38 ± 9 bpm, P = 0.44), HRRτ (CAF: 182.9 ± 40.5 s, PLA: 160.3 ± 62.2 s, P = 0.23) and HRRamp (CAF: 70.2 ± 17.4 bpm; PLA: 79.2 ± 17.4 bpm, P = 0.16) were not affected by caffeine ingestion.ConclusionsCaffeine ingestion increased the estimated glycolytic contribution during taekwondo combat simulation, but this did not result in any changes in performance, perceived exertion or parasympathetic reactivation.

Caffeine affects autonomic control of heart rate and blood pressure recovery after aerobic exercise in young adults: a crossover study

“…Some studies reported lower vagal reactivation and increased sympathetic activity during the recovery period 7,9 , while others did not observe expressive differences 8,10 . The same is true for cardiorespiratory variables, with changes in BP and HR during the recovery period 7 , as well as the absence of alterations 8 .…”

“…However, few studies have evaluated its effects during post-exercise recovery 7–10 , which is a critical period in which several modifications occur, among them changes in autonomic modulation 11 , which may promote an environment conducive to the development of rhythm disturbances, abnormal responses of heart rate (HR) and BP in predisposed individuals 11,12 .…”

“…Nevertheless, most of the studies that have evaluated the effects of caffeine supplementation on post-exercise recovery were performed with protocols of progressive and exhaustive exercises 7–9 , studying changes in physiological variables such as HR, BP, oxygen consumption and autonomic modulation 7–10 .…”

KD-64 – a new selective A2Aadenosine receptor antagonist has anti-inflammatory activity but contrary to the non-selective antagonist – caffeine does not reduce diet-induced obesity in mice

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Efeito da ingestão isolada de cafeí­na e bicarbonato de sódio sobre a contribuição energética, desempenho e reativação parassimpática em simulação de luta de taekwondo

“…Brevemente, a luta foi composta por 3 rounds de 2 min com 1 min de intervalo entre os rounds (tamanho da área 8 x 8 metros). As lutas foram arbitradas por um atleta de taekwondo faixa preta, com experiência em arbitragem, o qual não tinha conhecimento da condição experimental do atleta avaliado LOPES-SILVA et al, 2015). Embora a nova regra do taekwondo estabeleça o uso de coletes eletrônicos para proteger o tronco dos atletas e ao mesmo tempo permite a identificar mais dos pontos mais confiável e precisa possível, esse sistema não foi utilizado no estudo por causa de uma possível interferência no sistema de aquisição de sinal do analisador de gases.…”