Perceptual and Physiological Responses to Carbohydrate and Menthol Mouth-Swilling Solutions: A Repeated Measures Cross-Over Preliminary Trial

Carbohydrate and menthol mouth-swilling have been used to enhance exercise performance in the heat. However, these strategies differ in mechanism and subjective experience. Participants (n = 12) sat for 60 min in hot conditions (35 °C; 15 ± 2%) following a 15 min control period, during which the participants undertook three 15 min testing blocks. A randomised swill (carbohydrate; menthol; water) was administered per testing block (one swill every three minutes within each block). Heart rate, tympanic temperature, thermal comfort, thermal sensation and thirst were recorded every three minutes. Data were analysed by ANOVA, with carbohydrate intake controlled for via ANCOVA. Small elevations in heart rate were observed after carbohydrate (ES: 0.22 ± 90% CI: −0.09–0.52) and water swilling (0.26; −0.04–0.54). Menthol showed small improvements in thermal comfort relative to carbohydrate (−0.33; −0.63–0.03) and water (−0.40; from −0.70 to −0.10), and induced moderate reductions in thermal sensation (−0.71; from −1.01 to −0.40 and −0.66; from −0.97 to −0.35, respectively). Menthol reduced thirst by a small to moderate extent. These effects persisted when controlling for dietary carbohydrate intake. Carbohydrate and water may elevate heart rate, whereas menthol elicits small improvements in thermal comfort, moderately improves thermal sensation and may mitigate thirst; these effects persist when dietary carbohydrate intake is controlled for.

Perceptual and Physiological Responses to Carbohydrate and Menthol Mouth-Swilling Solutions

Carbohydrate and menthol mouth-swilling have been used to enhance exercise performance in the heat. However, these strategies differ in mechanism and subjective experience. Participants (n=12) sat for 60 min in hot conditions (35°C; 15±2%), following a 15 min control period, participants undertook three 15 min testing blocks. A randomised swill (Carbohydrate; Menthol; Water) was administered per testing block (one swill every three minutes within each block). Heart rate, tympanic temperature, thermal comfort, thermal sensation and thirst were recorded every three minutes. Data were analysed by ANOVA, with carbohydrate intake controlled for via ANCOVA. Small elevations in heart rate were observed after carbohydrate (ES: 0.22 ± 90% CI: -0.09 to 0.52) and water swilling (0.26; -0.04 to 0.54). Menthol showed small improvements in thermal comfort relative to carbohydrate (-0.33; -0.63 to 0.03) and water (-0.40; -0.70 to -0.10), and induced moderate reductions in thermal sensation (-0.71; -1.01 to -0.40 and -0.66; -0.97 to -0.35, respectively). Menthol reduced thirst by a small to moderate extent. These effects persisted when controlling for dietary carbohydrate intake. Carbohydrate and water may elevate heart rate, whereas menthol elicits small improvements in thermal comfort, moderately improves thermal sensation and may mitigate thirst; these effects persist when dietary carbohydrate intake is controlled for.

Accuracy and Validity of Commercially Available Kayak Ergometers

Methods:This study compared 3 commercially available ergometers for within- and between-brands difference to a first-principle calibration rig. Results:All ergometers underestimated true mean power, with errors of 27.6% ± 3.7%, 4.5% ± 3.5%, and 22.5% ± 1.9% for the KayakPro, WEBA, and Dansprint, respectively. Within-brand ergometer power differences ranged from 17 ± 9 to 22 ± 11 W for the KayakPro, 3 ± 4 to 4 ± 4 W for the WEBA, and 5 ± 3 to 5 ± 4 W for the Dansprint. The linear-regression analysis showed that most kayak ergometers have a stable coefficient of variation (0.9–1.7%) with a moderate effect size. Conclusion:Taken collectively, these findings show that different ergometers present inconsistent outcomes. Therefore, we suggest that athlete testing be conducted on the same ergometer brand, preferably the same ergometer. Optimally, that ergometer should be calibrated using a first-principle device before any athlete testing block.

Dopaminergic Modulation of Motor Timing in Healthy Volunteers Differs as a Function of Baseline DA Precursor Availability

Although numerous experiments in patients and animals implicate the dopamine (DA) system in timing, there are relatively few studies examining this effect in healthy volunteers. Moreover, the majority of these studies employed tasks of perceptual timing. We therefore investigated the DA modulation of motor timing in healthy volunteers using Acute Phenylalanine/Tyrosine Depletion (APTD), an amino-acid drink that reduces concentrations of the DA precursors tyrosine and phenylalanine. We also examined how APTD’s effects on timing might differ as a function of underlying DA function, as indexed by baseline levels of DA precursors. 18 healthy volunteers performed a Mixed Temporal Reproduction task, in which reproduction of five different sample durations (500 ms–1500 ms) were tested within a single testing block. Reproduction times conformed to Vierordt’s Law, such that the shortest durations were overestimated and the longest ones underestimated. Yet contrary to reported effects in Parkinson’s disease, we found no DA modulation of this ‘migration’ effect in our healthy volunteers. Instead, APTD produced systematic shifts in reproduction time across all durations. However, the direction of the shift differed according to individual differences in baseline levels of DA precursor availability. Specifically, APTD slowed reproduction times in participants with low baseline DA precursor levels whereas it speeded them in participants with high baseline levels. These apparently paradoxical effects can be reconciled in terms of the inverted U-shaped relationship between DA function and cognition. Finally, APTD had no effect on a test of temporal production in which participants were asked to provide spontaneous estimates of a one-second time interval. The differential effect of APTD on the reproduction versus production tasks suggests DA modulates the magnitude of the duration initially encoded into working memory, rather than clock-speed.

A New Framework for Fuzzy Modeling Using Genetic Algorithm

This paper presents a new framework for fuzzy modeling using genetic algorithm. A model of actual object in the real world should satisfy various criteria, such as precision, generality, noise immunity, etc. It has been difficult for the fuzzy modeling to allocate proper weights on these criteria. The framework introduced in this paper consists of a model generation block and a model-testing block. The model generation block generates candidates of fuzzy model under criteria with higher importance, and the model-testing block tests the candidates under notso-important criteria. This division of criteria can put emphasis on the criteria in the generation block and less on those in the testing block. Simulations are done to show the effectiveness of the proposed framework.