Previous studies have researched the ergogenic effect of caffeine in different shooting actions, but none of them in a stressful combat action. This study aimed to analyse the effect of a dose of 400 mg of caffeine monohydrate on the psycho-physiological response and marksmanship of soldiers in close quarter combat (CQC). We analysed the heart rate, blood lactate concentration, cortical arousal, state anxiety and marksmanship of 19 soldiers in the Spanish Army (38.9 ± 4.1 years; 177.4 ± 5.3 cm; 78.8 ± 7.6 kg) before and after a CQC simulation in a double-blind procedure. Caffeine intake did not improve shooting performance in CQC; however, it increased cognitive and somatic anxiety levels.
Practitioner summary: According to the previous literature, the ingestion of caffeine could help soldiers in operations conducted in sleep deprivation conditions, but in stressful combat situations it does not improve the marksmanship of soldiers.
Keywords: anxiety; combat; cortical arousal; heart rate; lactate; marksmanship; military; stress.