Search

This study aimed to determine whether caffeine gum influenced perceptual-cognitive and physical performance during the extra-time period of simulated soccer match-play. Semiprofessional male soccer players (n = 12, age: 22 ± 3 years, stature: 1.78 ± 0.06 m, mass: 75 ± 9 kg) performed 120-min soccer-specific exercise on two occasions. In a triple-blind, randomized, crossover design, players chewed caffeinated (200 mg; caffeine) or control (0 mg; placebo) gum for 5 min following 90 min of soccer-specific exercise. Perceptual-cognitive skills (i.e., passing accuracy, reaction time, composure, and adaptability) were assessed using a soccer-specific virtual reality simulator, collected pre- and posttrial. Neuromuscular performance (reactive-strength index, vertical jump height, absolute and relative peak power output, and negative vertical displacement) and sprint performance (15 and 30 m) were measured at pretrial, half-time, 90 min, and posttrial. Caffeine gum attenuated declines in reaction time (pre: 90.8 ± 0.8 AU to post: 90.7 ± 0.8 AU) by a further 4.2% than placebo (pre: 92.1 ± 0.8 AU to post: 88.2 ± 0.8 AU; p <.01). Caffeine gum reduced composure by 4.7% (pre: 69.1 ± 0.8 AU to post: 65.9 ± 0.8 AU) versus placebo (pre: 68.8 ± 0.8 AU to post: 68.3 ± 0.8 AU; p <.01). Caffeine gum did not influence any other variables (p >.05). Where caffeine gum is consumed by players prior to extra-time, reaction time increases but composure may be compromised, and neuromuscular and sprint performance remain unchanged. Future work should assess caffeine gum mixes with substances like L-theanine that promote a relaxed state under stressful conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

To identify key training load (TL) and intensity indicators in ice hockey, practice, and game data were collected using a wearable 200-Hz accelerometer and heart rate (HR) recording throughout a four-week (29 days) competitive period (23 practice sessions and 8 competitive games in 17 elite Danish players (n = 427 observations). Within-individual correlations among accelerometer- (total accelerations [Acctot], accelerations >2 m·s−2 [Acc2], total accelerations [Dectot], decelerations <- 2 m·s−2 [Dec2]), among HR-derived (time >85% maximum HR [t85%HRmax], Edwards’ TL and modified training impulse) TL indicators, and between acceleration- and HR-derived TL parameters were large to almost perfect (r = 0.69–0.99). No significant correlations were observed between accelerometer- and HR-derived intensity indicators. Three between- and two within-components were found. The K-means++ cluster analysis revealed five and four clusters for between- and within-loadings, respectively. The least Euclidean distance from their centroid for each cluster was reported by session-duration, Acctot, Dec2, TRIMPMOD, %t85HRmax for between-loadings, whereas session-duration, Acc2, t85HRmax and Dec2/min for within-loadings. Specific TL or intensity variables might be relevant to identify similar between-subject groups (e.g. individual player, playing positions), or temporal patterns (e.g. changes in TL or intensity over time). Our study provides insights about the redundancy associated with the use of multiple TL and intensity variables in ice hockey. [ABSTRACT FROM AUTHOR]

While it is well‐established that a period of interval training performed at near maximal effort, such as speed endurance training (SET), enhances intense exercise performance in well‐trained individuals, less is known about its effect on cardiac morphology and function as well as blood volume. To investigate this, we subjected 12 Under‐20 Danish national team ice hockey players (age 18 ± 1 years, mean ± SD) to 4 weeks of SET, consisting of 6–10 × 20 s skating bouts at maximal effort interspersed by 2 min of recovery conducted three times weekly. This was followed by 4 weeks of regular training (follow‐up). We assessed resting cardiac function and dimensions using transthoracic echocardiography and quantified total blood volume with the carbon monoxide rebreathing technique at three time points: before SET, after SET and after the follow‐up period. After SET, stroke volume had increased by 10 (2–18) mL (mean (95% CI)), left atrial end‐diastolic volume by 10 (3–17) mL, and circumferential strain improved by 0.9%‐points (1.7–0.1) (all P < 0.05). At follow‐up, circumferential strain and left atrial end‐diastolic volume were reverted to baseline levels, while stroke volume remained elevated. Blood volume and morphological parameters for the left ventricle, including mass and end‐diastolic volume, did not change during the study. In conclusion, our findings demonstrate that a brief period of SET elicits beneficial central cardiac adaptations in elite ice hockey players independent of changes in blood volume. [ABSTRACT FROM AUTHOR]

Objectives: This prospective cross-sectional study aimed to delineate associations between the performance and physiological responses to the Bruce test with two field tests, the futsal intermittent endurance test (FIET) and the Yo-Yo intermittent recovery test level-2 (YYIR2) in elite male futsal players, in order to endorse one of field test to futsal coaches., Methods: Fifteen elite futsal players (age 20 ± 3 years) have been participated in this study. Main outcome measurements included aerobic power, heart rate, blood lactate, ventilation, VO 2 , VCO 2 , VE-VO 2, and VE-VCO 2 indicators during FIET, YYIR2, and the Bruce test with carrying out a portable gas analyzer., Results: The Bruce test is significantly correlated with FIET and YYIR2 with respect to key outcome measures, including performance (r>0.59), aerobic power (r>0.69), heart rate (r>0.80), and blood lactate levels (r>0.60). The two field tests, FIET and YYIR2, were found to exhibit strong to perfect interrelationships. When examining the indicators such as VE, VO 2 , VCO 2 , VE-VO 2 , and VE-VCO 2 , moderate to strong correlations were identified across all three testing methods. However, the relationship between the Bruce test and YYIR2 was particularly noteworthy in terms of respiratory exchange ratio (RER) and metabolic equivalent of task (METS), showing a significant correlation., Conclusions: The YYIR2 and FIET appear to be valid practical field tests for measuring aerobic fitness and performance in competitive male futsal players., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)