Repeated low-dose caffeine ingestion during a night of total sleep deprivation improves endurance performance and cognitive function in young recreational runners: A randomized, double-blind, placebo-controlled study.

The present study aimed to assess the effects of repeated administration of low-dose caffeine during a night of total sleep deprivation on physical and cognitive performance. Twelve recreational runners (being non-habitual caffeine users) performed four test sessions in a double-blind randomized order after (i) a placebo or 6 mg/kg of caffeine ingestion during a baseline night (BN) or (ii) a placebo or three doses of 2 mg/kg of caffeine during a night of total sleep deprivation (TSD). At each session, they completed an exhaustive run at 75% of the final velocity in a Vameval test (Vvameval) around a 400 m outdoor athletics track and performed the correct detection and reaction time tasks. In comparison with BN, the TSD condition significantly impaired running performance, reaction time, and correct detections. On the contrary, caffeine intake improved exhaustive running performance after BN by 5.2% (p < .001) and after TSD by 8.9% (p < .001), increased correct detections after BN (p < .05) and TSD (p < .05), and decreased reaction time after BN (p < .01) and TSD (p < .05) compared to placebo. Therefore, the repeated ingestion of low-dose caffeine is an effective strategy to counteract the detrimental effects of total sleep deprivation on physical and cognitive performance.

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

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.

Partial sleep deprivation affects endurance performance and psychophysiological responses during 12-minute self-paced running exercise.

PURPOSE: This study aimed to investigate the effects of partial sleep deprivation (PSD) on physical performance and psychophysiological responses during 12-minute self-paced running exercise. METHODS: Twenty runners (20.8±1.1 years, 70.6±4.9 kg, 175.1±3.9 cm) performed, in a randomized order, two running self-paced field exercises after a normal sleep night (CONT, bedtime from 22:30 h to 06:30 h) and one night of PSD (bedtime from 00:30 h to 04:30 h). Core temperature and motivation were recorded before exercise. Speed, covered distance, heart rate (HR), rating of perceived exertion (RPE) and respiratory parameters (i.e., minute ventilation (VE), oxygen uptake (VO2) and carbon dioxide production (VCO2)) were assessed during exercise. Blood lactate concentration [La] was assessed 2 min after exercise. Simple reaction time (SRT), mood and barrage test (BT) were assessed before and after exercise. RESULTS: Higher RPE (p=0.01, d=0.90) and lower physical performance (i.e., p=0.001, d=0.59 for running speed and p=0.01, d=0.7 and Δ (%)=-6% for covered distance), following PSD, were obtained compared to CONT. Similarly, PSD attenuated core temperature (p=0.01, d=0.84), HR (p=0.006, ɳp2=0.45), VE (p=0.001, ɳp2=0.73), VO2 (p=0.001, ɳp2=0.96), BT (p<0.0005, ɳp2=0.86), SRT (p=0.0009, ɳp2=0.44) and mood (p<0.0005). However, VCO2, [La] and motivation score were not affected by sleep conditions. CONCLUSION: The decrease of running performance and the increase of physical discomfort after PSD could be the origin of the lower cardio-respiratory responses to the 12-minute self-paced exercise. Effective strategies should be introduced to overcome the deterioration of physical performance and physiological responses after PSD.