251 research outputs found
Performance indicators during international rugby union matches are influenced by a combination of physiological and contextual variables
Get PDFObjectivesResearch 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. We addressed this gap by monitoring 29 athletes from a training squad across eight international rugby matches.MethodsPre-match (8-9 am) measures of salivary testosterone and cortisol concentrations, sleep duration, pulse rate, muscle soreness, stress, mood, and motivation were taken. Contextual factors were playing time, internal training load (ITL), test-match experience, opponent ranking, and crowd size. Performance was indexed by coach and player ratings of performance (CRP, PRP) and quantitative metrics; offloads, turnovers, runs with ball in hand (RWB), tackles, passes, and defenders beaten (DFB).ResultsMorning cortisol, sleep and mood were positively related to CRP and PRP (standardised coefficient estimates from 0.17 to 0.22). Cortisol, sleep, stress, mood and motivation were associated with one (or more) of turnovers, RWB, tackles, passes and DFB (incidence rate ratio [IRR] from 0.74 to 1.40). Playing time was positively related to all quantitative performance indicators (IRR from 1.01 to 1.04) with ITL, opponent ranking, and crowd size predicting selected outputs (IRR from 0.89 to 1.15). The explanatory models varied (conditional R2 = 0.15 to 0.83) but were generally stronger with both physiological and contextual inputs.ConclusionsMultiple physiological and contextual factors appear to contribute to player performance in international rugby competition. Measurement of these factors may guide training and management practices, a potential practical consequence but also advancing understanding from marker to causal link
A longitudinal investigation of bidirectional and time-dependent interrelationships between testosterone and training motivation in an elite rugby environment
Get PDFIn 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. Thirty-six male athletes were monitored across training weeks before and after eight international rugby matches. Pre-breakfast measures of salivary testosterone and training motivation (1–10 rating) were taken on training, competition, and recovery days (up to 40 tests). Using a continuous-time (CT) model, within-person estimates of autoregressive effects (persistence) and cross-lagged effects (relationships) were derived. A stronger, more persistent temporal association was identified for testosterone than for motivation. Cross-lagged effects verified that training motivation was positively related to testosterone at latter time points (p < 0.001). Discrete-time analyses revealed a non-linear association; increasing in strength from a zero-time lag to peak after 2.83 days (standardized effect = 0.25), before dissipation over longer lagged intervals. The testosterone relationship with ensuing training motivation was also positive, but non-significant. Match effects also appeared (p < 0.001) with a predicted decline in training motivation, but a rise in testosterone, at match onset. In summary, a positive association emerged between within-person fluctuations in self-appraised motivation to train and testosterone concentration in an elite rugby environment. The lagged, non-linear nature of this relationship and match predictions on both outcomes support, and extend, theoretical models linking testosterone and competitive behaviors
The effects of oral creatine supplementation on health and disease
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Necessary Steps to Accelerate the Integration of Wearable Sensors Into Recreation and Competitive Sports
Get PDFA comparison of different heat maintenance methods implemented during a simulated half-time period in professional Rugby Union players
Get PDFObjectivesIn thermoneutral conditions, half-time is associated with reductions in body temperature that acutely impair performance. This laboratory-based study compared active, passive, and combined methods of half-time heat maintenance.DesignRandomised, counterbalanced, cross-overMethodsAfter a standardised warm-up (WU) and 15 min of rest, professional Rugby Union players (n = 20) completed a repeated sprint test (RSSA1). Throughout a simulated half-time (temperature: 20.5 ± 0.3 °C; humidity: 53 ± 5%), players then rested (Control) or wore a survival jacket (Passive) for 15 min, or performed a 7 min rewarm-up after either 8 min of rest (Active), or 8 min of wearing a survival jacket (Combined). A second RSSA (RSSA2) followed. Core temperature (Tcore) and peak power output (PPO; during countermovement jumps; CMJ) were measured at baseline, post-RSSA1, pre-RSSA2.ResultsAll half-time interventions attenuated reductions in Tcore (0.62 ± 0.28 °C) observed in Control (Passive: −0.23 ± 0.09 °C; Active: −0.17 ± 0.09 °C; Combined: −0.03 ± 0.10 °C, all p < 0.001) but Combined preserved Tcore the most (p < 0.001). All half-time interventions attenuated the 385 ± 137 W reduction in Control PPO (Passive: −213 ± 79 W; Active: −83 ± 72 W; Combined: +10 ± 52 W; all p < 0.001); with best PPO maintenance in Combined (p ≤ 0.001). The fastest sprints occurred in RSSA2 in Combined (6.74 ± 0.21 s; p<0.001) but Passive (6.82 ± 0.04 s) and Active (6.80 ± 0.05 s) sprints were 0.4% (p = 0.011) and 0.8% (p = 0.002) quicker than Control (6.85 ± 0.04 s), respectively.ConclusionsWhile the efficacy of passive and active heat maintenance methods was supported throughout a simulated half-time, a combined approach to attenuating heat losses appeared the most beneficial for Tcore and subsequent PPO and sprint performance in professional Rugby Union players
Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise
Get PDFIntroduction Repeated ischemic preconditioning (IPC) can improve muscle and pulmonary oxygen on-kinetics, blood flow and exercise efficiency but these effects have not been investigated severe hypoxia. The aim of the current study was to evaluate the effects of 7 d of IPC on resting and exercising muscle and cardio-pulmonary responses to severe hypoxia. Methods Fourteen subjects received either: 1) 7 d of repeated lower-limb occlusion (4 x 5 min, 217±30 mm Hg) at limb occlusive pressure (IPC) or SHAM (4 x 5 min, 20 mm Hg). Subjects were tested for resting limb blood flow (72), relative microvascular deoxyhemoglobin concentration ([HHB]) and pulmonary oxygen (V ̇O2p) responses to steady state and incremental exercise to exhaustion in hypoxia (fractional inspired O2 = 0.103), which was followed by 7 d of IPC or SHAM, and retesting 72 h post intervention. Results There were no effects of IPC on maximal oxygen consumption, time to exhaustion during the incremental test or minute ventilation and arterial oxygen saturation. However, the IPC group had higher delta efficiency based on pooled results and lower steady state delta[HHB] (IPC ~24% vs. SHAM ~6% pre-to-post), as well as slowing the [HHB] time constant (IPC ~26% vs. SHAM ~3% pre-to-post) and reducing the overshoot in [HHB]:V ̇O2 ratio during exercise onset. Conclusions Collectively, these results demonstrate that muscle O2 efficiency and microvascular O2 distribution can be improved by repeated IPC but there are no effects on maximal exercise capacity in a severe hypoxia
Concurrent adaptations in maximal aerobic capacity, heat tolerance, microvascular blood flow and oxygen extraction following heat acclimation and ischemic preconditioning
Get PDFWe investigated the effects of: 1) Ischemic pre-conditioning (IPC) plus a concurrent five-day heat acclimation + IPC (IPC + HA), 2) five-day HA with sham IPC (HA), or 3) control (CON) on thermoneutral measurements of endurance performance, resting measures of skeletal muscle oxygenation and blood flow. Twenty-nine participants were randomly allocated to three groups, which included: 1) five-days of repeated leg occlusion (4 x 5-min) IPC at limb occlusive pressure, plus fixed-intensity (55% O2max) cycling HA at ∼36 °C/40% humidity; 2) HA plus sham IPC (20 mmHg) or 3) or CON (thermoneutral 55% O2max plus sham IPC). In IPC + HA and HA, there were increases in maximal oxygen consumption (O2max) (7.8% and 5.4%, respectively; P  0.05). Changes (P  0.05). Five-days of either HA or IPC + HA can enhance markers of endurance performance in cooler environments, alongside improved muscle oxygen extraction, blood flow, exercising muscle efficiency and O2 pulse at higher intensities, thus suggesting the occurrence of peripheral adaptation. Both HA and IPC + HA enhance the adaptation of endurance capacity, which might partly relate to peripheral changes
Acute effects of wearable thigh and shank loading on spatiotemporal and kinematic variables during maximum velocity sprinting
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