Ketone Monoester Ingestion Alters Metabolism and Simulated Rugby Performance in Professional Players.

Ketone ingestion can alter metabolism but effects on exercise performance are unclear, particularly with regard to the impact on intermittent-intensity exercise and team-sport performance. Nine professional male rugby union players each completed two trials in a double-blind, randomized, crossover design. Participants ingested either 90 ± 9 g carbohydrate (CHO; 9% solution) or an energy matched solution containing 20 ± 2 g CHO (3% solution) and 590 mg/kg body mass β-hydroxybutyrate monoester (CHO + BHB-ME) before and during a simulated rugby union-specific match-play protocol, including repeated high-intensity, sprint and power-based performance tests.

A longitudinal investigation of bidirectional and time-dependent interrelationships between testosterone and training motivation in an elite rugby environment.

In sport, testosterone has been positioned as a substrate for motivation with both directional and time dependencies. However, evidence is scarce when considering the complexities of competitive sport and no work has explicitly modeled these dependencies. To address these gaps, we investigated the bidirectional and time-dependent interrelationships between testosterone and training motivation in an elite rugby environment.

Performance indicators during international rugby union matches are influenced by a combination of physiological and contextual variables.

Objectives: Research has linked physiological (e.g., hormonal, affective, fatigue) outcomes to performance indicators in rugby competition, but no work has integrated and contextualised these factors within a test-match environment.

Relationships between physical qualities and key performance indicators during match-play in senior international rugby union players.

The use of physical tests to profile physical capabilities, and provide training direction to athletes is common practice. Likewise, in professional team sports, notational analysis codes the key contributions of each player during competition. Limited studies have however investigated relationships between physical capabilities and key performance indicators (KPIs) of rugby union match-play.

Assessing worst case scenarios in movement demands derived from global positioning systems during international rugby union matches: Rolling averages versus fixed length epochs.

The assessment of competitive movement demands in team sports has traditionally relied upon global positioning system (GPS) analyses presented as fixed-time epochs (e.g., 5-40 min).

The effect of oral contraceptive use on salivary testosterone concentrations and athlete performance during international field hockey matches.

Objectives: To investigate the effect of oral contraceptive (OC) use on salivary testosterone (sal-T) concentrations and performance-related statistics in international field hockey matches.

Design: A cohort observational study with repeated measures.

Methods: Twenty-three elite female athletes were monitored across four international field hockey matches over a nine-day period.

Can salivary testosterone and cortisol reactivity to a mid-week stress test discriminate a match outcome during international rugby union competition?

Objectives: Evidence suggests that stress-induced changes in testosterone and cortisol are related to future competitive behaviours and team-sport outcomes. Therefore, we examined whether salivary testosterone and cortisol reactivity to a mid-week stress test can discriminate a match outcome in international rugby union competition.

Design: Single group, quasi-experimental design with repeated measures.

Movement Demands of Elite Under-20s and Senior International Rugby Union Players.

This study compared the movement demands of elite international Under-20 age grade (U20s) and senior international rugby union players during competitive tournament match play. Forty elite professional players from an U20 and 27 elite professional senior players from international performance squads were monitored using 10Hz global positioning systems (GPS) during 15 (U20s) and 8 (senior) international tournament matches during the 2014 and 2015 seasons. Data on distances, velocities, accelerations, decelerations, high metabolic load (HML) distance and efforts, and number of sprints were derived.

Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes.

Ketosis, the metabolic response to energy crisis, is a mechanism to sustain life by altering oxidative fuel selection. Often overlooked for its metabolic potential, ketosis is poorly understood outside of starvation or diabetic crisis. Thus, we studied the biochemical advantages of ketosis in humans using a ketone ester-based form of nutrition without the unwanted milieu of endogenous ketone body production by caloric or carbohydrate restriction.

Movement Demands of Elite U20 International Rugby Union Players.

The purpose of this study was to quantify movement demands of elite international age grade (U20) rugby union players during competitive tournament match play. Forty elite professional players from an U20 international performance squad were monitored using 10 Hz global positioning systems (GPS) during 15 international tournament matches during the 2014/15 and 2015/16 seasons. Data on distances, velocities, accelerations, decelerations, high metabolic load (HML) distance and efforts, and number of sprints were derived.

Profiling the time-course changes in neuromuscular function and muscle damage over two consecutive tournament stages in elite rugby sevens players.

Objectives: Many International Rugby Board (IRB) sevens competitions require that two tournament stages are played over consecutive weekends, but the impact this has on player physical performance and recovery is lacking. We examined the influence of two consecutive tournaments on neuromuscular function (NMF) and muscle damage in rugby sevens players.

Design: Ten elite international rugby sevens players completed this observational study over 2 tournaments, separated by 5 days, during the IRB sevens series.

Measurement of steroid hormones in saliva: Effects of sample storage condition.

Measurement of steroid hormones in saliva is increasingly common in elite sport settings. However, this environment may enforce handling and storage practices that introduce error in measurement of hormone concentrations. We assessed the influence of storage temperature and duration on reproducibility of salivary steroid levels.

Dihydrotestosterone is elevated following sprint exercise in healthy young men.

Dihydrotestosterone (DHT) exerts both functional and signaling effects extending beyond the effects of testosterone in rodent skeletal muscle. As a primer for investigating the role of DHT in human skeletal muscle function, this study aimed to determine whether circulating DHT is acutely elevated in men following a bout of repeat sprint exercise and to establish the importance of training status and sprint performance to this response. Fourteen healthy active young men (Vo2max 61.

Electrostimulation's enhancement of recovery during a rugby preseason.

Unlabelled: Rugby preseason training involves high-volume strength and conditioning training, necessitating effective management of the recovery-stress state to avoid overtraining and maximize adaptive gains.

Purpose: Compression garments and an electrostimulation device have been proposed to improve recovery by increasing venous blood flow. These devices were assessed using salivary testosterone and cortisol, plasma creatine kinase, and player questionnaires to determine sleep quality, energy level, mood, and enthusiasm.

Intermittent lower-limb occlusion enhances recovery after strenuous exercise.

Repeated cycles of vascular occlusion followed by reperfusion initiate a protective mechanism that acts to mitigate future cell injury. Such ischemic episodes are known to improve vasodilation, oxygen utilization, muscle function, and have been demonstrated to enhance exercise performance. Thus, the use of occlusion cuffs represents a novel intervention that may improve subsequent exercise performance.

Designing a warm-up protocol for elite bob-skeleton athletes.

Purpose: To investigate how different warm-ups influenced subsequent sled-pull sprint performance in Olympic-level bob-skeleton athletes as part of their preparation for the 2010 Winter Olympics.

Methods: Three female and 3 male athletes performed 5 different randomized warm-ups of differing intensities, durations, and timing relative to subsequent testing, each 2 days apart, all repeated twice. After warm-ups, testing on a sled-pull sprint over 20 m, 3 repeats 3 min apart, took place.

Acute caffeine ingestion's increase of voluntarily chosen resistance-training load after limited sleep.

Introduction: This study aimed to determine whether caffeine ingestion would increase the workload voluntarily chosen by athletes in a limited-sleep state.

Methods: In a double-blind, crossover study, 16 professional rugby players ingested either a placebo or 4 mg/kg caffeine 1 hr before exercise. Athletes classified themselves into nondeprived (8 hr+) or sleep-deprived states (6 hr or less).

Circadian disruption and remedial interventions: effects and interventions for jet lag for athletic peak performance.

Jet lag has potentially serious deleterious effects on performance in athletes following transmeridian travel, where time zones are crossed eastwards or westwards; as such, travel causes specific effects related to desynchronization of the athlete's internal body clock or circadian clock. Athletes are particularly sensitive to the effects of jet lag, as many intrinsic aspects of sporting performance show a circadian rhythm, and optimum competitive results require all aspects of the athlete's mind and body to be working in tandem at their peak efficiency. International competition often requires transmeridian travel, and competition timings cannot be adjusted to suit individual athletes.

Baseline strength can influence the ability of salivary free testosterone to predict squat and sprinting performance.

The objective of this study was to determine if salivary free testosterone can predict an athlete's performance during back squats and sprints over time and the influence baseline strength on this relationship. Ten weight-trained male athletes were divided into 2 groups based on their 1 repetition maximum (1RM) squats, good squatters (1RM > 2.0 × body weight, n = 5) and average squatters (1RM < 1.

Skill execution and sleep deprivation: effects of acute caffeine or creatine supplementation - a randomized placebo-controlled trial.

Background: We investigated the effects of sleep deprivation with or without acute supplementation of caffeine or creatine on the execution of a repeated rugby passing skill.

Method: Ten elite rugby players completed 10 trials on a simple rugby passing skill test (20 repeats per trial), following a period of familiarisation. The players had between 7-9 h sleep on 5 of these trials and between 3-5 h sleep (deprivation) on the other 5.

The application of risk management in sport.

The process of risk management can be implemented as part of a best practice management system within the sport and leisure sector. The process enables risk factors that might lead to injuries to be identified and the levels of risk associated with activities to be estimated and evaluated. This information can be utilised proactively by sports governing bodies and participants to identify preventive and therapeutic interventions in order to reduce the frequency of occurrence and/or severity of injuries within their sports.