Mental Rehearsal Improves Passing Skill and Stress Resilience in Rugby Players.

PURPOSE: Mental rehearsal is commonly employed, with positive visualization proposed to enhance complex skill performance. Additionally, video stimulus has been associated with enhanced kinesthetic sensations and rapid hormone fluctuations that may contribute to enhancing mental rehearsal and the conscious and unconscious emotional state for skill execution. Here, we assessed the impact of a 15-minute mental rehearsal intervention on rugby-specific tasks and the associated hormone profile. METHODS: Professional rugby players (N = 10) volunteered for a randomized crossover study. They completed three 15-minute preparatory phases (positive or negative video-guided mental rehearsal or self-directed mental rehearsal alone) prior to an exercise stressor and rugby-specific passing task. Salivary testosterone and cortisol were monitored to assess stress responses. RESULTS: Performance during the rugby passing task was improved following the positive video condition (91% [7.4%]) compared to the negative video (79% [6.0%]; ES: 1.22 ± 0.75) and self-visualization (86% [5.8%]; ES: 0.58 ± 0.75), with a significant correlation observed between passing performance and salivary testosterone (r = .47 ± .34, P = .0087). Positive video imagery prior to an exercise stressor also significantly enhanced physiological stress resilience (r = .39 ± .36, P = .0352). CONCLUSIONS: This pilot study demonstrates that mental rehearsal was enhanced by appropriate, context-specific video presentation. We propose that the interaction between sex steroids, the adrenal axis, and subsequent conscious and unconscious behaviors may be relevant to competitive rugby. Specifically, we suggest that relatively elevated free testosterone imparts a degree of stress resilience, which may lead to enhanced expression of competitive behaviors and provide an enhanced state for rugby skill execution

Role of creatine supplementation on exercise-induced cardiovascular function and oxidative stress

Many degenerative diseases are associated with increased oxidative stress. Creatine has the potential to act as an indirect and direct antioxidant; however, limited data exist to evaluate the antioxidant capabilities of creatine supplementation within in vivo human systems. This study aimed to investigate the effects of oral creatine supplementation on markers of oxidative stress and antioxidant defenses following exhaustive cycling exercise. Following preliminary testing and two additional familiarization sessions, 18 active males repeated two exhaustive incremental cycling trials (T1 and T2) separated by exactly 7 days. The subjects were assigned, in a double-blind manner, to receive either 20 g of creatine (Cr) or a placebo (P) for the 5 days preceding T2. Breath-by-breath respiratory data and heart rate were continually recorded throughout the exercise protocol and blood samples were obtained at rest (preexercise), at the end of exercise (postexercise), and the day following exercise (post24 h). Serum hypdroperoxide concentrations were elevated at postexercise by 17 ± 5% above preexercise values (p = 0.030). However, supplementation did not influence lipid peroxidation (serum hypdroperoxide concentrations), resistance of low density lipoprotein to oxidative stress (t1/2max LDL oxidation) and plasma concentrations of non-enzymatic antioxidants (retinol, α-carotene, β-carotene, α-tocopherol, γ-tocopherol, lycopene and vitamin C). Heart rate and oxygen uptake responses to exercise were not affected by supplementation. These findings suggest that short-term creatine supplementation does not enhance non-enzymatic antioxidant defence or protect against lipid peroxidation induced by exhaustive cycling in healthy males

Physiological and performance effects of carbohydrate gels consumed prior to the extra-time period of prolonged simulated soccer match-play

Objectives: The physiological and performance effects of carbohydrate-electrolyte gels consumed before the 30 min extra-time period of prolonged soccer-specific exercise were investigated. Design: Randomised, double-blind, crossover. Methods: Eight English Premier League academy soccer players performed 120 min of soccer-specific exercise on two occasions while consuming fluid-electrolyte beverages before exercise, at half-time and 90 min. Carbohydrate-electrolyte (0.7 ± 0.1 g·kg-1 BM) or energy-free placebo gels were consumed ~5 min before extra-time. Blood samples were taken before exercise, at half-time and every 15 min during exercise. Physical (15-m and 30-m sprint speed, 30-m sprint maintenance and countermovement jump height) and technical (soccer dribbling) performance was assessed throughout each trial. Results: Carbohydrate-electrolyte gels improved dribbling precision (+29 ± 20%) and raised blood glucose concentrations by 0.7 ± 0.8 mmol·l-1 during extra-time (both p 3% during half-time (all p < 0.05). Conclusions: Carbohydrate-electrolyte gel ingestion raised blood glucose concentrations and improved dribbling performance during the extra-time period of simulated soccer match-play. Supplementation did not attenuate reductions in physical performance and hydration status that occurred during extra-time

Neuromuscular, physiological and perceptual responses to an elite netball tournament

To examine responses to an International netball tournament, female athletes (n= 11) played three matches over consecutive days. External (accelerometry) and internal (heart rate; HR, session; sRPE, and differential; dRPE, rating of perceived exertion) load measures quantified match intensity. On match-day mornings, and three days after match 3, well-being (brief assessment of mood; BAM+), biochemical (creatine kinase concentration; CK), neuromuscular (jump height; JH, peak power output; PPO) and endocrine function (salivary cortisol; C, testosterone; T, concentrations) were assessed. External load was similar between matches whereas dRPE and sRPE were greatest for match 3. Following match 1, CK increased, whereas BAM+, JH, C and T decreased. Following two matches, BAM+, PPO, and T decreased with CK increasing versus baseline. Following consecutive matches, CK (likely moderate; 27.9% ± 19.5%) and C (possibly moderate; 43.3% ± 46.8%) increased, whilst BAM+ (possibly moderate; −20.6% ± 24.4%) decreased. Three days post-tournament BAM+, T, PPO, and JH decreased. Mid-court elicited higher mean HR (possibly moderate; 3.7% ± 3.8%), internal and external intensities (possibly very large; 85.7% ± 49.6%) compared with goal-based positions. Consecutive matches revealed a dose–response relationship for well-being and physiological function; a response evident three days post-tournament