Estimated Sweat Loss, Fluid and Carbohydrate Intake, and Sodium Balance of Male Major Junior, AHL, and NHL Players During On-Ice Practices

The physiology of ice hockey performance: An update

Ice hockey is an intense team sport characterized by repeated bursts of fast-paced skating, rapid changes in speed and direction and frequent physical encounters. These are performed in on-ice shifts of ~30-80 s interspersed with longer sequences of passive recovery, resulting in about 15-25 min on-ice time per player. Nearly 50% of the distance is covered at high-intensity skating speeds and with an accentuated intense activity pattern in forwards compared to defensemen. During ice hockey match-play, both aerobic and anaerobic energy systems are significantly challenged, with the heart rate increasing toward maximum levels during each shift, and with great reliance on both glycolytic and phosphagen ATP provision. The high-intensity activity pattern favors muscle glycogen as fuel, leading to pronounced reductions despite the relatively brief playing time, including severe depletion of a substantial proportion of individual fast- and slow-twitch fibers. Player-tracking suggests that the ability to perform high-intensity skating is compromised in the final stages of a game, which is supported by post-game reductions in repeated-sprint ability. Muscle glycogen degradation, in particular in individual fibers, as well as potential dehydration and hyperthermia, may be prime candidates implicated in exacerbated fatigue during the final stages of a game, whereas multiple factors likely interact to impair exercise tolerance during each shift. This includes pronounced PCr degradation, with potential inadequate resynthesis in a proportion of fast-twitch fibers in situations of repeated intense actions. Finally, the recovery pattern is inadequately described, but seems less long-lasting than in other team sports.

Fluid Balance, Sodium Losses and Hydration Practices of Elite Squash Players during Training

Elite squash players are reported to train indoors at high volumes and intensities throughout a microcycle. This may increase hydration demands, with hypohydration potentially impairing many key performance indicators which characterise elite squash performance. Consequently, the main aim of this study was to quantify the sweat rates and sweat [Na+] of elite squash players throughout a training session, alongside their hydration practices. Fourteen (males = seven; females = seven) elite or world class squash player’s fluid balance, sweat [Na+] and hydration practices were calculated throughout a training session in moderate environmental conditions (20 ± 0.4 °C; 40.6 ± 1% RH). Rehydration practices were also quantified post-session until the players’ next training session, with some training the same day and some training the following day. Players had a mean fluid balance of −1.22 ± 1.22% throughout the session. Players had a mean sweat rate of 1.11 ± 0.56 L·h−1, with there being a significant difference between male and female players (p < 0.05), and a mean sweat (Na+) of 46 ± 12 mmol·L−1. Players training the following day were able to replace fluid and sodium losses, whereas players training again on the same day were not. These data suggest the variability in players hydration demands and highlight the need to individualise hydration strategies, as well as training prescription, to ensure players with high hydration demands have ample time to optimally rehydrate.

A questionnaire study on the knowledge, attitudes, and practices of fluid replacement and urination among Chinese elite athletes

OBJECTIVE

To evaluate the knowledge, attitudes and practices (KAP) of Chinese elite athletes about fluid replacement and urination.

METHODS

A cross-section study was carried out among Chinese national and national youth teams from March to April 2020, using a pretested questionnaire. The 42-questions questionnaire was designed to assess the KAP regarding fluid replacement and urination. The questionnaire included knowledge of fluid replacement (KFR), attitudes of fluid replacement (AFR), knowledge of urination (KU), and attitudes of urination (AU), which were awarded 20 scoring points. Descriptive statistics, independent samples t-tests, one-way ANOVA, Pearson's correlation analysis, Multiple linear stepwise regression and Chi-square test were performed.

RESULTS

A total of 779 valid questionnaires were collected and the effective rate is 98.4%. We finally conducted an assessment of 646 questionnaires of elite athletes. The mean score for KFR, AFR, KU, and AU was 2.8±1.3, 2.3±0.6, 3.0±1.5, and 2.1±0.8, respectively, with higher scores indicating positive hydration knowledge and attitudes. KFR and AFR scores of winter sports athletes were higher than those of summer sports athletes(P<0.05). Athletes who had lower athletic grades and training years had a worse KFR(P<0.05). Only 31.0% athletes knew that rehydration should be carried out before, during, and after training, which was scarcer among women, lower-athletic grades athletes, or athletes with lower training years (P<0.05). Male athletes had a worse KU but a better AU than female athletes(P<0.05). And athletes who were international-class athletic grades had the highest KU scores(P<0.05). The athletic grades and sport events were the main factors influencing the total scores of knowledge and attitudes (P<0.05, 95% CI -0.789--0.168,95% CI 0.025-1.040). Most of athletes tend to get hydration knowledge from internet. In practices, thirst is the main reason for rehydration (77.9%). The percentages of athletes with normal urine color (42.0%), frequency (75.0%,) and volume (20.0%) were low.

CONCLUSIONS

These findings indicate that Chinese elite athletes did not have sufficient KAP on fluid replacement and urination, more marked in the individuals who were summer sport events, the lower athletic grades and in lower training years. It is recommended that education should be provided in the early stages of professional training for athletes.

Internal Load of Female Varsity Ice Hockey Players During Training and Games During a Season

This study quantified internal load, using sessional rating of perceived exertion (sRPE) and heart-rate derived training impulse (TRIMP), of female varsity ice hockey players throughout a season. Twenty-four female (19.8±1.4 yr, 68.0±6.9 kg) varsity ice hockey players participated in this prospective cohort study. Internal load was captured using sRPE and TRIMP for each on-ice session. Internal load was significantly higher (p<0.05) for games (sRPE: 324±202 AU, TRIMP: 95±60 AU) compared to training (sRPE: 248±120 AU, TRIMP: 68±32 AU). Overall, goalies had a higher internal load than forwards (sRPE and TRIMP) and defence (TRIMP), with no differences between forwards and defence. Micro-cycle periodization was present, with training sessions several days prior to game days having the highest internal load (sRPE and TRIMP) and tapering down as subsequent training sessions approached game day. For the meso-cycle assessment, for both training and competition combined, the post-season sRPE was greater than the pre-season (p=0.002) and regular season (p<0.001). Lastly, the association between sRPE and TRIMP, revealed a large, statistically significant relationship (r=0.592, p<0.001). Internal load was greater during competitions, training sessions and subsequent internal loads suggested prioritization around game days, the post-season phase demanded the highest internal load and there was a strong correlation between sRPE and TRIMP.

Key Nutritional Considerations for Youth Winter Sports Athletes to Optimize Growth, Maturation and Sporting Development

Despite a wealth of sport nutrition guidelines for adult athletes, there are currently no nutrition guidelines for youth winter sports athletes. Whilst it may be pragmatic to apply nutrition guidelines for adult athletes to youth winter sports athletes, it is inappropriate. Due to a paucity of research on youth athletes, it is impossible to provide evidence-based guidelines for this population, so careful extrapolation from the theoretical and practical considerations that apply to other athletic groups is necessary. Youth winter sport athletes undergo rapid biological growth and maturation which influences their nutritional requirements. A varied and balanced diet that ensures sufficient energy availability for optimal growth and maturation as well as sporting performance is the cornerstone of youth athlete nutrition and should also allow for youth athletes to meet their micronutrient requirements. In some cases, micronutrient status (e.g., vitamin D and iron) should be monitored and optimized if appropriate by a medical professional. Dietary supplement use is prevalent amongst youth athletes, however is often unnecessary. Education of youth athletes, their parents and coaches on best nutritional practices as well as the risks associated with dietary supplements is vital for their long-term athletic development. Further research in youth winter sports athletes across different stages of growth and maturation competing in a variety of sports is urgently required in order to inform nutritional guidelines for this population.

Mild dehydration impaired intermittent sprint performance and thermoregulation in females

The effects of mild dehydration during ice hockey are well-studied in males but not females. In a randomized, crossover design, 11 female varsity hockey players drank no fluid (1.7% ± 0.3% body mass loss) or water to maintain hydration during simulated-hockey exercise. Core temperature (P < 0.01) and perceived fatigue (P = 0.02) were higher and sprint power lower (P < 0.01) when mildly dehydrated. Thus, mild dehydration may impair hockey performance and thermoregulation while increasing perceived fatigue in females. Novelty Female stop-and-go sport athletes may benefit their in-game sprint performance and thermoregulation by following personalized in-game hydration to prevent becoming mildly dehydrated.

Hydration Status and Cardiovascular Function

Hypohydration, defined as a state of low body water, increases thirst sensations, arginine vasopressin release, and elicits renin–angiotensin–aldosterone system activation to replenish intra- and extra-cellular fluid stores. Hypohydration impairs mental and physical performance, but new evidence suggests hypohydration may also have deleterious effects on cardiovascular health. This is alarming because cardiovascular disease is the leading cause of death in the United States. Observational studies have linked habitual low water intake with increased future risk for adverse cardiovascular events. While it is currently unclear how chronic reductions in water intake may predispose individuals to greater future risk for adverse cardiovascular events, there is evidence that acute hypohydration impairs vascular function and blood pressure (BP) regulation. Specifically, acute hypohydration may reduce endothelial function, increase sympathetic nervous system activity, and worsen orthostatic tolerance. Therefore, the purpose of this review is to present the currently available evidence linking acute hypohydration with altered vascular function and BP regulation.