Acute caffeine ingestion improves 3-km run performance, cognitive function, and psychological state of young recreational runners

Highlights

• The ingestion of 3 mg/kg body mass of caffeine enhanced the 3-km performance time of young athletes.

• Low-dose caffeine consumption improved cognitive function and psychological state at rest and after a 3-km run competition.

• The intake of low-dose caffeine did not affect the oxidative stress induced by short-term endurance exercise.

Abstract

The current study aimed to assess the effects of caffeine administration on performance time, cognition, psychomotor state, and blood levels of oxidative stress markers following a 3-km run competition. Thirteen recreational runners performed two test sessions in a double-blind randomized order after placebo or 3 mg/kg of body mass of caffeine. At each session, subjects completed a 3-km running competition around a 400 m outdoor athletics track. Cognitive tasks (attention and reaction time), psychological tests (Feeling scale and Hooper), and blood collection were carried out before and after the run. In comparison with placebo, caffeine ingestion enhanced the 3-km performance time by 1.1% (p < 0.001) (10.13 ± 0.69 min versus 10.25 ± 0.72 min), improved attention by 15.6% (p < 0.001) and reaction-time by 5.9% (p < 0.05), increased good-feeling by 15.7% (p < 0.01), and lowered stress-feeling by 17.6% (p < 0.01) and pain-sensation by 11.3% (p < 0.05). However, no significant effects of caffeine were observed on oxidative stress markers. Only exercise resulted in increased levels of glutathione peroxidase (GPX) (12.2%, 8.8%) (p < 0.05), reduced glutathione (GSH) (17.6%, 10.1%) (p < 0.05), superoxide dismutase (SOD) (7.6%, 6.5%) (p < 0.05) and malondialdehyde (MDA) (10.3%, 9.6%) (p < 0.05), for both the placebo and caffeine groups respectively. In conclusion, our study highlighted that the consumption of 3 mg/kg caffeine could be an improving agent for the physical, cognitive, and psychological states without affecting the oxidative stress state during such a running competition.

Introduction

Caffeine (1,3,7-trimethylxanthine) is a psychoactive substance consumed worldwide. This alkaloid is naturally found in various dietary products such as coffee, tea, chocolate, and soda (Burke, 2008). The optimal caffeine dose ranges from 3 to 6 mg/kg body mass ingested 1 h before exercise, and its half-life lasts between 2.5 and 4.5 h in humans (Graham, 2001). Because of its psychostimulant properties, this drug is widely used by athletes to improve psychological and cognitive performance (Snel and Lorist, 2011; Souissi et al., 2018). It is also an effective strategy to enhance physical and cognitive performances for athletes who compete in the morning hours (Souissi et al., 2019). Moreover, it was reported that caffeine consumption improves endurance performance time such as 5-km run (Matthew et al., 2008) and 8-km run (Khcharem et al., 2020) performances.

Physiologic responses to exercise are more pronounced with high doses of caffeine (>6 mg/kg bm) by enhancing skeletal and cardiac muscle tonicity and also by increasing blood lactate and glycerol levels (Tarnopolsky, 2008; Yang et al., 2009). However, side effects such as anxiety, nervousness, irritability, and jitteriness could be produced (Tunnicliffe et al., 2008). Psychological and cognitive states are improved with reduced side effects at moderate and particularly low doses of caffeine (≤3 mg/kg bm). Indeed, mood, vigilance, and reaction time are enhanced, and the feeling of pain is diminished (Lorist and Snel, 2008; Spriet, 2014).

The mechanism by which caffeine enhances endurance performance, psychological state, and cognitive function stem from its effects on the central nervous system (CNS) through adenosine receptor antagonism. Indeed, the micro-molar concentrations of caffeine in tissues block adenosine-receptors (A1 and A2a), which can form a functional heteromer with dopamine-receptors (D1 and D2) in different regions of the brain. Thereby, caffeine antagonizes the effects of adenosine and indirectly promotes the stimulatory effects of dopamine on psychomotor and cognitive states (Fredholm et al., 1999).

On the other hand, previous studies had shown that endurance exercise could induce oxidative stress and muscle damage which have a detrimental impact on athletic performance (Powers and Jackson, 2008). Therefore, it would seem very important to investigate the effect of caffeine consumption on oxidative stress. The latter is defined as an imbalance between the production of free radicals and the antioxidant capacities of the tissues, leading to cell damage. Subsequent oxidative damage, which results in an increased level of lipid peroxidation (malondialdehyde (MDA)), could be neutralized via elevated antioxidant defenses, such as superoxide dismutase (SOD), glutathione peroxidase (GPX), and reduced glutathione (GSH) (Alessio et al., 2000).

Regarding the effect of caffeine on oxidative stress state, the results reported through literature were ambiguous. Some of the caffeine-derived effects may favor the production of free radicals during exercise (Baez et al., 1997). However, this drug is reported to play a potential antioxidant role, probably due to its effect on the trapping of reactive oxygen species (Devasagayam et al., 1996).

Most of the experiments on this topic investigated either the physical, cognitive or psychological caffeine's impact and were conducted under laboratory conditions. Indeed, ecological valid approaches simulating official outdoor competitions were scarcely used (Bridge and Jones, 2006; Matthew et al., 2008), due to the difficulty of controlling field studies (Tauler et al., 2013). In addition, only a few studies using moderate or high caffeine doses examined its effect on oxidative stress state during endurance exercise (Olcina et al., 2006, Olcina et al., 2008; Tauler et al., 2013; Salicio et al., 2017). Moreover, the relative efficacy of low-dose caffeine ingestion in improving physical, cognitive, and psychological states under such conditions is still unknown.

Accordingly, this study aimed to determine the effect of a relatively low dose of caffeine (3 mg/kg; equivalent to about 200 mg or 2 espressos for an adult weighing 70 kg) on the performance time of 3-km running competition, cognitive function, psychological state, and oxidative stress markers (GPX, GSH, SOD, and MDA) for thirteen young recreational runners.