Effects of one-night sleep deprivation on selective attention and isometric force in adolescent karate athletes

BACKGROUND: Most of the available literature related to aspects of sleep deprivation is primarily focused on memory and learning, and studies regarding its effects on selective attention and/or physical performance are scarce. Moreover, the available literature includes general population or people involved in team sports (e.g. volleyball). However, only few studies were performed on athletes involved in combat sports (e.g. karate). The aim of the present study was to determine the effects of a total one-night sleep deprivation (1NSD) on activation and inhibition processes of selective attention and on maximal isometric force in karate athletes. METHODS: Twelve young karate athletes (mean age 16.9 +/- 0.8 years) were enrolled. The protocol consists of two successive sessions: a normal night's sleep (NNS) and a total 1NSD. After each night, athletes performed selective attention and muscle strength tests during the same following three times (T) of the day: T1(NNS) or T1(1NSD): 8-9 a.m.; T2(NNS) or T2(1NSD): 12 a.m.-1 p.m.; T3(NNS) or T3(1NSD): 4-5 p.m. Activation (simple [SRT] and choice reaction times [CRT]) and inhibition (negative priming) processes were evaluated using Superlab v. 4.5 software (Cedrus Corporation, San Pedro, CA, USA). Maximal force and maximal force time (MFT) of brachial biceps isometric contraction were evaluated (Ergo System (R), Globus, Codogne, Italy). A non-parametric test was used to evaluate the sessions (NNS vs. SND for the same time period) and time (T1(NNS) vs. 1NSD) effects. RESULTS: All athletes completed all tests after a NNS. Twelve, eleven and four athletes completed all tests at T1(1NSD), T2(1NSD) and T3(1NSD), respectively. As for sessions effects, no statistically significant difference was found. As for time effects, a significant increase in SRT at T2(1NSD) vs. T1(NNS) (345 +/- 47 vs. 317 +/- 33 ms, respectively), a significant increase in MFT at T2(1NSD) vs. T1(NNS) (2172 +/- 260 vs. 1885 +/- 292 ms, respectively), and no significant changes in CRT and negative priming reaction time or MFT data were observed. CONCLUSIONS: 1NSD affects both activation processes of selective attention and maximal isometric strength, two key skills in combat sports.