The effect of carbohydrate mouth rinse on maximal strength and strength endurance

It has been previously reported that carbohydrate (CHO) mouth rinse can improve exercise performance. The proposed mechanism involves increased activation of brain regions believed to be responsible for reward/motivation and motor control. Since strength-related performance is affected by central drive to the muscles, it seems reasonable to hypothesize that the positive CNS response to oral CHO sensing may counteract the inhibitory input from the muscle afferent pathways minimizing the drop in the central drive. The purpose of the current study was to test if CHO mouth rinse affects maximum strength and strength endurance performance. Twelve recreationally strength-trained healthy males (age 24.08 +/- 2.99 years; height 178.09 +/- 6.70 cm; weight 78.67 +/- 8.17 kg) took part in the study. All of the tests were performed in the morning, after an 8 h overnight fasting. Subjects were submitted to a maximum strength test (1-RM) and a strength endurance test (six sets until failure at 70% of 1-RM), in separate days under three different experimental conditions (CHO mouth rinse, placebo-PLA mouth rinse and control-CON) in a randomized crossover design. The CHO mouth rinse (25 ml) occurred before every attempt in the 1-RM test, and before every set in the endurance strength test. Blood glucose and lactate were measured immediately before and 5 min post-tests. There were no significant differences in 1-RM between experimental conditions (CHO 101 +/- 7.2 kg; PLA 101 +/- 7.4 kg; CON 101 +/- 7.2 kg; p = 0.98). Furthermore, there were no significance between trial differences in the number of repetitions performed in each set (p = 0.99) or the total exercise volume (number of repetitions x load lifted [kg]) (p = 0.98). A main effect for time (p < 0.0001) in blood lactate concentration was observed in both tests (1-RM and strength endurance). Blood glucose concentration did not differ between conditions. In conclusion, CHO mouth rinse does not affect maximum strength or strength endurance performance.

Effect of bandwidth knowledge of results on the learning of a grip force control task

An experiment was conducted to investigate the persistence of the effect of ""bandwidth knowledge of results (KR)"" manipulated during the learning phase of performing a manual force-control task. The experiment consisted of two phases, an acquisition phase with the goal of maintaining 60% maximum force in 30 trials, and a second phase with the objective of maintaining 40% of maximum force in 20 further trials. There were four bandwidths of KR: when performance error exceeded 5, 10, or 15% of the target, and a control group (0% bandwidth). Analysis showed that 5, 10, and 15% bandwidth led to better performance than 0% bandwidth KR at the beginning of the second phase and persisted during the extended trials.