The effectiveness of heat preparation and alleviation strategies for cognitive performance: A systematic review.

A range of occupational and performance contexts (e.g. military personnel operations, emergency services, sport) require the critical maintenance of cognitive performance in environmentally challenging environments. Several reviews exist which evaluate the effectiveness of heat preparation strategies to facilitate physical performance. To date, no review has explored the usefulness of heat preparation strategies for cognitive performance. Therefore, this systematic review aimed to evaluate a range of interventions for the maintenance of cognitive performance, during or following active or passive heat exposure. Studies to be included were assessed by two authors reviewing title, abstract, and full-text. Forty articles were identified which met the inclusion criteria. Interventions were categorised into chronic (i.e. acclimation/acclimatisation) and acute strategies (i.e. hydration, cooling, supplementation, psychological). The results indicate that medium-term consecutive heat acclimation may mitigate some cognitive deficits under heat stress, although heat acclimation effectiveness could be influenced by age. Further, pre-cooling appears the most effective cooling method for maintaining cognitive performance under heat stress, although results were somewhat ambiguous. The hydration literature showed that the most effective hydration strategies were those which individualised electrolyte fortified fluid volumes to match for sweat loss. Limited research exploring psychological interventions indicates that motivational self-talk could be facilitative for maintaining cognitive skills following exercise in hot conditions. These findings can be used to help inform strategies for maintaining critical cognitive and decision-making skills in hot environments.

Rapid Weight Loss Practices Within Olympic Weightlifters.

ABSTRACT: Gee, TI, Campbell, P, Bargh, MJ, and Martin, D. Rapid weight loss practices within Olympic weightlifters. J Strength Cond Res 37(10): 2046-2051, 2023-Rapid weight loss (RWL) practices are common among athletes to "make weight" for a chosen bodyweight class. This study's purpose was to investigate RWL prevalence, magnitude, and methods within Olympic weightlifters from Great Britain. Subjects (n = 39, male = 22, female = 17) were recruited from International Weightlifting Federation lifting populations (mandatory two-hour competition weigh-in). Subjects were categorized into competitive groups based on Sinclair coefficient total (high, mid, low) and also gender (male, female). The validated Rapid Weight Loss Questionnaire was used to establish RWL magnitude and practices. Of respondents, 33 of 39 (84.6%) had purposely acutely reduced body mass to compete, a higher proportion present within females (94.1%) than males (77.3%). The cohort's mean habitual precompetition acute body mass loss was 3.8 ± 1.7% and the "rapid weight loss score" (RWLS) was 23.6 ± 9.5. Across competitive groups there were no significant differences in habitual or highest precompetition body mass loss, postcompetition body mass gain or RWLS (p > 0.05). However, females attributed a significantly greater "highest" relative precompetition body mass loss compared with males (7.4 vs 4.9%, p = 0.045). For RWL methods used, frequencies of "always" and "sometimes" were reported highest for "restricting fluid ingestion" (81.8%), "gradual dieting" (81.8%), and "water loading" (54.5%). The prevalence of RWL is high among competitive Olympic weightlifters, and especially within the sampled female athletes. Magnitude of RWL was similar across different standards of athlete; however, female lifters demonstrated a higher maximum precompetition RWL.

A comparison of rapid weight loss practices within international, national and regional powerlifters.

Background: Rapid weight loss (RWL) practices are common amongst strength-sport athletes to 'make weight' for a chosen weight class. Aim: This study compared the RWL practices of International Powerlifting Federation (IPF) powerlifters from Great Britain. Methods: Participants (n = 69, male = 36, female = 33) were recruited from IPF lifting populations (mandatory <2-hour competition weigh-in). Participants were categorised based on highest level of competition (regional, national and international) and also sex (male and female). The previously validated 'Rapid Weight Loss Questionnaire' established RWL practices, however also included an open-ended question regarding thoughts, feeling and mood during RWL. Results: Nearly all participants (97%) had purposely acutely reduced body mass to compete, with an average typical pre-competition loss of 4.2%. Regional competitors reported a higher 'typical' body mass loss compared to international competitors (5.5% vs 3.3%, p = 0.004). Females reported a greater 'highest' body mass loss than males (6.7% vs 5.3%, p = 0.028). Fluid restriction (86.5%), water loading (67.2%) and increased exercise (49.2%) were the RWL methods most commonly used 'always' or 'sometimes'. Content analysis revealed a predominance of negative perceptions during RWL with the emergence of codes; fatigue, sensations, anxiety, low mood and irritation, accounting for ∼70% of responses. Conclusion: Prevalence of RWL is high amongst competitive powerlifters, with many competitors attributing negative perceptions during the weight-cutting process. The magnitude of reported acute RWL within regional lifters was beyond where performance decrements are commonly seen (>5%), this should be cautioned against given the IPF's mandatory <2-hour competition weigh-in.

Why do team-sport athletes drink fluid in excess when exercising in cool conditions?

This study assessed the potential physiological and perceptual drivers of fluid intake and thirst sensation during intermittent exercise. Ten male rugby players (17 ± 1 years, stature: 179.1 ± 4.2 cm, body mass (BM): 81.9 ± 8.1 kg) participated in six 6-min small-sided games, interspersed with 2 min rest, where fluid intake was ad libitum during rest periods. Pre- and postmeasurements of BM, subjective ratings (thirst, thermal comfort, thermal sensation, mouth dryness), plasma osmolality (POsm), serum sodium concentration (S[Na+]), haematocrit and haemoglobin (to calculate plasma volume change; PV) were taken. Fluid intake was measured during rest periods. BM change was -0.17 ± 0.59% and fluid intake was 0.88 ± 0.38 L. Pre- to post-POsm decreased (-3.1 ± 2.3 mOsm·kg-1; p = 0.002) and S[Na+] remained similar (-0.3 ± 0.7 mmol·L-1, p = 0.193). ΔPV was 5.84 ± 3.65%. Fluid intake displayed a relationship with pre-POsm (r = -0.640, p = 0.046), prethermal comfort (r = 0.651; p = -0.041), ΔS[Na+] (r = 0.816, p = 0.004), and ΔPV (r = 0.740; p = 0.014). ΔThirst sensation displayed a relationship with premouth dryness (r = 0.861, p = 0.006) and Δmouth dryness (r = 0.878, p = 0.004). Yet a weak positive relationship between Δthirst sensation and fluid intake was observed (r = 0.085, p = 0.841). These data observed in an ambient temperature of 13.6 ± 0.9 °C, suggest team-sport athletes drink in excess of fluid homeostasis requirements and thirst sensation in cool conditions; however, this was not influenced by thermal discomfort.

Mouth Rinsing With Carbohydrate Solutions at the Postprandial State Fail to Improve Performance During Simulated Cycling Time Trials.

Mouth rinsing with carbohydrate (CHO) solutions during cycling time trials results in performance enhancements; however, most studies have used approximately 6% CHO solutions. Therefore, the purpose of this study was to compare the effectiveness of mouth rinsing with 4, 6, and 8% CHO solutions on 1-hour simulated cycling time trial performance. On 4 occasions, 7 trained male cyclists completed at the postprandial period, a set amount of work as fast as possible in a randomized counterbalanced order. The subjects rinsed their mouth for 5 seconds, on completion of each 12.5% of the trial, with 25 ml of a non-CHO placebo and 4, 6, and 8% CHO solutions. No additional fluids were consumed during the time trial. Heart rate (HR), ratings of perceived exertion (RPE), thirst (TH), and subjective feelings (SF) were recorded after each rinse. Furthermore, blood samples were drawn every 25% of the trial to measure blood glucose and blood lactate concentrations, whereas whole-body CHO oxidation was monitored continuously. Time to completion was not significant between conditions with the placebo, 4, 6, and 8% conditions completing the trials in 62.0 ± 3.0, 62.8 ± 4.0, 63.4 ± 3.4, and 63 ± 4.0 minutes, respectively. There were no significant differences between conditions in any of the variables mentioned above; however, significant time effects were observed for HR, RPE, TH, and SF. Post hoc analysis showed that TH and SF of subjects in the CHO conditions but not in the placebo were significantly increased by completion of the time trial. In conclusion, mouth rinsing with CHO solutions did not impact 1-hour cycling performance in the postprandial period and in the absence of fluid intake. Our findings suggest that there is scope for further research to explore the activation regions of the brain and whether they are receptive to CHO dose, before specific recommendations for athletic populations are established. Consequently, mouth rinsing as a practical strategy for coaches and athletes is questionable under specific conditions and should be carefully considered before its inclusion. Emphasis should be focused on appropriate dietary and fluid strategies during training and competition.