Mild dehydration impaired intermittent sprint performance and thermoregulation in females

Cross-Sectional Study of the Anthropometric Profile and Nutrient Status of Elite Female Ice Hockey Players: Differences by Play Position

Both the characteristics of ice hockey and the environmental conditions in which it is played affect the maintenance of the player's nutritional status and, therefore, their state of health and performance. The primary aim of this work was to examine the anthropometric profile, estimated energy expenditure, and macronutrient and micronutrient dietary intake of elite female ice hockey players by play position. As a secondary aim, their dietary intakes were compared with the recommendations. Hypotheses suggest variations in body composition based on ice hockey players' positions, with the expectation that these athletes may not align with energy and nutrient recommendations. Fifteen elite female ice hockey players were anthropometrically measured, basal metabolic rate and total energy expenditure were estimated, a 3-day, 24 h recall questionnaire was registered, and the results were compared with the recommended dietary intake for the Spanish population. Each player's position on the field requires an individualized physical and nutritional approach. There are no significant imbalances (p > 0.05) between energy and nutrient intake in relation to the Recommended Daily Intake (RDI); however, increasing the consumption of vegetables and seafood while reducing meat and fat intake would assist these athletes in maintaining a healthier energy balance, optimizing body composition, and aligning with nutritional parameters that are better suited to enhance physical performance.

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.

INTENSIFICATION OF ABDOMINAL CORE SKILLS IN MUSCULAR STRENGTH TRAINING FOR SPRINTER ATHLETES

ABSTRACT Introduction Running is a speed-based physical activity, and abdominal core strength training is a good technique for athletes. The method of abdominal core strength training consists of training the muscles of the central part of the human body, which also aims to improve the physical coordination of its practitioners. Objective Analyze the effects of abdominal core strength training on athletes’ physical performance and performance in competitions. Methods Twenty sprinters were selected as volunteers and had their EMG signals and muscular endurance of the lower body muscles compared during the experiment. The athletes performed an abdominal core training cycle. The statistical method was used to perform an analysis of the obtained data. These experimental data were adjusted, and significant correlations were discovered. The research results of this paper provide a theoretical basis for formulating the athletes’ training strategies. Results The maximum muscular endurance of male and female sprinters was statistically different (P<0.05). Fitness indicators improved in sprinters after abdominal core strength training. The studies were statistically different (P<0.05). Athletes’ performance improved after abdominal core strength training. The data were statistically significant (P<0.05). Conclusion The physical performance and performance of sprinters are positively correlated with abdominal core strength training. Sprinters should focus on abdominal core strength training in their daily training. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Potential effect of beetroot juice supplementation on exercise economy in well-trained females

This study examined if acute dietary nitrate supplementation (140 mL beetroot juice, BRJ) would reduce oxygen consumption (V̇O2) during cycling at power outputs of 50 and 70% maximal oxygen consumption in 14 well-trained female Canadian University Ringette League athletes. BRJ had no effect on V̇O2 or heart rate but significantly reduced ratings of perceived exertion (RPE) at both intensities. Individually, 4 participants responded to BRJ supplementation with a ≥3% reduction in V̇O2 at the higher power output. Novelty: Acute BRJ supplementation did not improve exercise economy in well-trained females, but significantly reduced RPE. However, 4/14 subjects did respond with a ≥3% V̇O2 reduction.

Carbohydrate hastens hypervolemia achieved through ingestion of aqueous sodium solution in resting euhydrated humans

PURPOSE

Ingesting beverages containing a high concentration of sodium under euhydrated conditions induces hypervolemia. Because carbohydrate can enhance interstitial fluid absorption via the sodium-glucose cotransporter and insulin-dependent renal sodium reabsorption, adding carbohydrate to high-sodium beverages may augment the hypervolemic response.

METHODS

To test this hypothesis, we had nine healthy young males ingest 1087 ± 82 mL (16-17 mL per kg body weight) of water or aqueous solution containing 0.7% NaCl, 0.7% NaCl + 6% dextrin, 0.9% NaCl, or 0.9% NaCl + 6% dextrin under euhydrated conditions. Each drink was divided into six equal volumes and ingested at 10-min intervals. During each trial, participants remained resting for 150 min. Measurements were made at baseline and every 30 min thereafter.

RESULTS

Plasma osmolality decreased with water ingestion (P ≤ 0.023), which increased urine volume such that there was no elevation in plasma volume from baseline (P ≥ 0.059). The reduction in plasma osmolality did not occur with ingestion of solution containing 0.7% or 0.9% NaCl (P ≥ 0.051). Consequently, urine volume was 176-288 mL smaller than after water ingestion and resulted in plasma volume expansion at 60 min and later times (P ≤ 0.042). In addition, net fluid balance was 211-329 mL greater than after water ingestion (P ≤ 0.028). Adding 6% dextrin to 0.7% or 0.9% NaCl solution resulted in plasma volume expansion within as little as 30 min (P ≤ 0.026), though the magnitudes of the increases in plasma volume were unaffected (P ≥ 0.148).

CONCLUSION

Dextrin mediates an earlier hypervolemic response associated with ingestion of high-sodium solution in resting euhydrated young men. (247/250 words).

Sex differences in the physiological responses to exercise-induced dehydration: consequences and mechanisms

Physiological strain during exercise is increased by mild dehydration (∼1%-3% body mass loss). This response may be sex-dependent, but there are no direct comparative data in this regard. This review aimed to develop a framework for future research by exploring the potential impact of sex on thermoregulatory and cardiac strain associated with exercise-induced dehydration. Sex-based comparisons were achieved by comparing trends from studies that implemented similar experimental protocols but recruited males and females separately. This revealed a higher core temperature (T_c) in response to exercise-induced dehydration in both sexes; however, it seemingly occurred at a lower percent body mass loss in females. Although less clear, similar trends existed for cardiac strain. The average female may have a lower body water volume per body mass compared with males, and therefore the same percent body mass loss between the sexes may represent a larger portion of total body water in females potentially posing a greater physiological strain. In addition, the rate at which T_c increases at exercise onset might be faster in females and induce a greater thermoregulatory challenge earlier into exercise. The T_c response at exercise onset is associated with lower sweating rates in females, which is commonly attributed to sex differences in metabolic heat production. However, a reduced sweat gland sensitivity to stimuli, lower fluid output per sweat gland, and sex hormones promoting fluid retention in females may also contribute. In conclusion, the limited evidence suggests that sex-based differences exist in thermoregulatory and cardiac strain associated with exercise-induced dehydration, and this warrants future investigations.