Effects of caffeine and maltodextrin mouth rinsing on P300, brain imaging, and cognitive performance.

Caffeine (CAF) and maltodextrin (MALT) mouth rinses (MR) improve exercise performance. The current experiment aims to determine the effect of CAF and MALT MR on cognitive performance and brain activity. Ten healthy male subjects (age 27 ± 3 yr) completed three experimental trials. Each trial included four Stroop tasks: two familiarization tasks, and one task before and one task after an MR period. The reaction time (in milliseconds) and accuracy (percent) of simple, congruent, and incongruent stimuli were assessed. Electroencephalography was applied throughout the experiment to record brain activity. The amplitudes and latencies of the P300 were determined during the Stroop tasks before and after the MR period. Subjects received MR with CAF (0.3 g/25 ml), MALT (1.6 g/25 ml), or placebo (PLAC) in a randomized, double-blind, crossover design. During MR, the brain imaging technique standardized low-resolution brain electromagnetic tomography was applied. Magnitude-based inferences showed that CAF MR is likely trivial (63.5%) and likely beneficial (36.4%) compared with PLAC MR, and compared with MALT MR likely beneficial to reaction time on incongruent stimuli (61.6%). Additionally, both the orbitofrontal and dorsolateral prefrontal cortex were activated only during CAF MR, potentially explaining the likely beneficial effect on reaction times. MALT MR increased brain activity only within the orbitofrontal cortex. However, this brain activation did not alter the reaction time. Furthermore, no significant differences in the accuracy of stimuli responses were observed between conditions. In conclusion, only CAF MR exerted a likely beneficial effect on reaction time due to the subsequent activation of both the orbitofrontal and dorsolateral prefrontal cortexes.

Low-back problems in recreational self-contained underwater breathing apparatus divers: prevalence and specific risk factors.

Low-back problems (LBP) are one of the most common musculoskeletal disorders in the general population, with reported lifetime prevalences of 50% to 80%. Also, certain sports participants (e.g. gymnasts, alpine skiers, runners) are at risk of LBP and its repercussions. This epidemiological study was undertaken to examine the lifetime and 1-year prevalence of LBP among recreational Flemish self-contained breathing apparatus (scuba) divers and to identify general and sport-specific risk factors associated with the occurrence of LBP. A retrospective self-assessment questionnaire was developed and assessed for validity and reliability, to gather data concerning demographics, LBP prevalence and associated risk factors and injuries among active scuba divers. A total of 181 recreational scuba divers (men: n = 138, mean age 40.3 +/- 12.8 years; women: n = 43, mean age 35.0 +/- 10.9 years) from 10 randomly selected internationally recognised scuba diving clubs participated in the study. Lifetime and 1-year prevalence of LBP among recreational Flemish scuba divers were 55.8% and 50.3%, respectively. General risk factors for LBP were found to include prior history of LBP, structural abnormalities, heavy workload, pregnancy and parturition, general fatigue and bending forwards and backwards. Scuba divers suffering from LBP generally had a significantly higher dive certificate than those without LBP (p = 0.007). Symptomatic scuba divers also used significantly more weights on their weight belts during indoor training (p = 0.003) and during outdoor dives with a dry suit (p = 0.044) as compared to asymptomatic scuba divers. In scuba diving, reliable sport-specific risk factors for LBP were found to be scarce. Further biomechanical research is required to point out whether or not scuba diving characteristics actually contribute to LBP.