Small Performance Effects of a Practical Mixed-Methods Cooling Strategy in Elite Team Sport Athletes.

Purpose: The ingestion of ice slurry and application of ice towels can elicit favorable physiological, perceptual, and performance benefits when used individually; however, the combined use and effectiveness of these practical cooling strategies have not been assessed using a sport-specific performance test, based on actual match demands, in an elite team sport context. Methods: Ten non-heat acclimated elite male rugby sevens athletes undertook two cycling heat response tests (HRT) designed to be specific to the demands of rugby sevens in hot conditions (35°C, 80% rH). In a crossover design, the HRTs were conducted with (COOLING) and without (HOT) the combined use of internal (ice slushy ingestion) and external (application of ice towels to the head, neck, and face) pre- and per-cooling strategies. Physiological, perceptual, and performance variables were monitored throughout each HRT. Results: COOLING resulted in reductions in mean tympanic temperature (-0.4 ± 0.2°C; d = 1.18); mean heart rate (-5 ± 8 bpm; d = 0.53); thermal discomfort (-0.5 ± 0.9 AU; d = 0.48); and thirst sensation (-1.0 ± 1.1 AU; d = 0.61) during the HRT. COOLING also resulted in a small increase in 4-min time trial power output (by 7 ± 33 W, ~3%; d = 0.35) compared to HOT. Discussion: A combination of internal and external pre- and per-cooling strategies can result in a range of small physiological, perceptual, and performance benefits during a rugby sevens specific HRT, compared to undertaking no cooling. Practitioners should include such strategies when performing in hot conditions.

Practical application of a mixed active and passive heat acclimation protocol in elite male Olympic team sport athletes.

To investigate effectiveness and retention of heat acclimation (HA) integrated within an elite rugby sevens team training program, 12 elite male rugby sevens athletes undertook 10 days of mixed active/passive HA across 2 weeks of normal training. Physiological and performance variables were assessed using a sport-specific, repeated high-intensity heat-response test pre-HA; after 5 days (mid-HA) and 10 days (post-HA); and 16 days post-HA (decay). Resting, submaximal, and end-exercise core temperatures were lower at mid-HA (≤-0.26 °C; d ≥ -0.47), post-HA (≤-0.30 °C; d ≥ -0.72), and decay (≤-0.29 °C; d ≥ -0.56), compared to pre-HA. Sweat rate was greater at post-HA compared to pre-HA (0.3 ± 0.3 L·h-1; d = 0.63). Submaximal heart rate (HR) was lower at mid- (-9 ± 4 bpm; d = -0.68) and post-HA (-11 ± 4 bpm; d = -0.90) compared to pre-HA. Mean and peak 6 s power output improved at mid-HA (83 ± 52 W; 112 ± 67 W; d ≥ 0.47) and post-HA (125 ± 62 W; 172 ± 85 W; d ≥ 0.72) compared to pre-HA. Improvements in HR and performance persisted at decay (d ≥ 0.66). The initial 5 days of mixed-methods HA elicited many typical HA adaptations, with an additional 5 days eliciting further thermoregulatory, sudomotor, and performance improvements. Adaptations were well retained after 16 days of normal training, without any further heat stimulus. The trial was retrospectively registered with the Australian New Zealand Clinical Trials Registry (ACTRN12622000732785).

The relationship between physiological and performance variables during a hot/humid international rugby sevens tournament.

To characterise physiological responses to competing in an international rugby sevens tournament played in hot/humid conditions, core temperature (Tc) and Tc predictors were collected from 11 elite men's rugby sevens athletes competing in the Oceania sevens tournament in Suva, Fiji. Tc, body mass change, sweat electrolytes, playing minutes, total running distance, high speed running distance (HSD), psychrometric wet bulb temperature and exertional heat illness symptoms were collected pre, during and post games. Linear mixed-models were used to assess the effect of Tc predictors on post-game Tc, along with differences in Tc across measurement periods. Compared to baseline on both tournament days, mean Tc was higher during all between game (recovery) measures (all d >1.30, p <0.01). On both tournament days, eight athletes reached a post-game Tc >39.0°C, with several athletes reaching >39.0°C during warm-ups. Mean post-game Tc was related to playing minutes, total running distance, HSD, and post warm-up Tc (all p < 0.01). The Tc during warm-ups and games regularly exceeded those demonstrated to be detrimental to repeated sprint performance (> 39°C). Warm-up Tc represents the easiest predictor of post-game Tc to control via time/intensity modulation and the use of appropriate pre- and per-cooling strategies. Practitioners should be prepared to modulate warm-ups and other heat preparation strategies based on likely environmental conditions during hot/humid tournaments.

The relationship between changes in interstitial creatine kinase and game-related impacts in rugby union.

AIM: The primary purpose of this study was to investigate the relationship between the pre-game to post-game changes in creatine kinase concentration (Delta[CK]) and impact-related game statistics in elite rugby union players. METHODS: Twenty-three elite male rugby union players each provided interstitial fluid samples obtained via electrosonophoresis (ESoP) 210 min before and within a maximum time of 30 min after up to five rugby union games. Specific game statistics that were deemed to be important in determining the relationship between impact and [CK] were obtained from AnalyRugby software for each individual player. Regression equations to predict Delta[CK] from game statistics were created using a backwards random-effects maximum likelihood regression. RESULTS: The Delta[CK] (mean (SD)) from pre-game to post-game was 926.8 (204.2) IU. Game time and time defending were significantly correlated to Delta[CK] in both the forwards and backs. The predicted Delta[CK] (mean (95% confidence limit)) was 1439.8 (204.9) IU for the forwards and 545.3 (78.0) IU for the backs and was significantly correlated with the actual Delta[CK] (r = 0.69 and r = 0.74). CONCLUSIONS: CK increased from pre-game to post-game in a position-specific manner. A large proportion of the Delta[CK] can be explained by physical impact and thus can be predicted using a prescribed number of game statistics. As the Delta[CK] is an indicator of muscle damage, the prediction of Delta[CK] provides a theoretical basis for recovery strategies and adjustment of subsequent training sessions after rugby union games.

Effectiveness of post-match recovery strategies in rugby players.

OBJECTIVES: To examine the effectiveness of four interventions on the rate and magnitude of muscle damage recovery, as measured by creatine kinase (CK). METHODS: 23 elite male rugby players were monitored transdermally before, immediately after, 36 hours after, and 84 hours after competitive rugby matches. Players were randomly assigned to complete one of four post-match strategies: contrast water therapy (CWT), compression garment (GAR), low intensity active exercise (ACT), and passive recovery (PAS). RESULTS: Significant increases in CK activity in transdermal exudate were observed as a result of the rugby match (p<0.01). The magnitude of recovery in the PAS intervention was significantly worse than in the ACT, CWT, and GAR interventions at the 36 and 84 hour time points (p<0.05). CONCLUSIONS: An enhanced rate and magnitude of recovery was observed in the ACT, CWT, and GAR treatment groups when compared with the PAS group. Low impact exercise immediately post-competition, wearing compression garments, or carrying out contrast water therapy enhanced CK clearance more than passive recovery in young male athletes.

Physical demands of elite Rugby League referees, part two: heart rate responses and implications for training and fitness testing.

UNLABELLED: The purpose of this study was to assess whether any characteristic patterns of heart rate (HR) responses could be identified in National Rugby League (NRL) referees (n= 6) during matches played in the 2001 season. The data have been plotted and discussed, in order that exercise program planning practitioners may gain improved understandings of the physiological requirements for referees. Some specific training suggestions have also been made. METHODS: The HR was recorded every five seconds throughout six competition NRL matches; using a heart rate monitor with a built-in memory. RESULTS: The specific magnitudes of referees' HR mean values varied between individuals, possibly due to specific game intensities, referee fitness, and age. All referees however exhibited similar HR response patterns; characterised by frequent (13-20 per match) large transient upward and downward shifts (>20 beats.minute(-1)). Periods of elevated HR extended for between five sec and eight min at a time, and were further characterised as a typical cyclic wave of HR elevation and recovery (ranging from 99.2+/-12.4 beats.minute(-1) to 176.5+/-11.8 beats.minute(-1) [mean +/-95% CI]), with a work to rest ratio of 2:1. Steady state HR was not achieved at any time during any match. CONCLUSIONS: The findings of the present study, taken together with a recent motion analysis, indicate that Rugby League refereeing is a highly intermittent, variable intensity activity. Significant anaerobic contribution to performance appears likely. It is suggested that training and fitness assessment of athletes should reflect their specific demands; some specific recommendations have therefore been provided.

Physical demands of elite Rugby League referees: Part one--time and motion analysis.

The purpose of the present study was to accurately and reliably analyse the nature of movement undertaken by National Rugby League (NRL) referees during matches played in the 2000 season. The movements of NRL referees (n=5) were analysed from videotape footage of ten games. The researchers assigned each movement to one of six defined categories (stationary, walking forwards, jogging forwards, sprinting, sideways, and backwards), and recorded number of repetitions, movement durations, and distances covered during each specific movement category. Distance was estimated using on-field markings as known points. Mean total distance per game was 6.7 km +/- 0.4 km (mean +/- standard deviation), and was made up of approximately 940 movements per game. The data showed 87% of distance was made up of a cyclic activity comprising jogging forwards, then backwards at mean running speeds of 7.2 km x h(-1) and 10.8 km x h(-1) respectively (made up of 9s bursts on average, each separated by 3s breaks). However, this cyclic activity accounted for only 47% of time, as referees were stationary 41% of time. Play was continuous for 90s +/- 71s at each phase of play, and was followed by rest of 45s +/- 36s throughout matches (work to rest ratio was 2:1). These findings suggest Rugby League refereeing is a highly intermittent activity and therefore training and fitness assessments should reflect these specific demands experienced during a game.

Muscular and cardiorespiratory effects of pseudoephedrine in human athletes.

AIMS: Pseudoephedrine (PSE) is a readily available over-the-counter nasal decongestant which is structurally similar to amphetamine and is included on the International Olympic Committee's list of banned substances. However to date, little research has supported its putative ergogenic effect. This study investigated whether a 180 mg dose of PSE ingested 45 min prior to exercise enhanced short-term maximal exercise performance and/or altered related physiological variables. METHODS: A randomised, double-blind, crossover study in 22 healthy male athletes. RESULTS: Maximum torque (mean +/- s.d., n = 22) produced in an isometric knee extension exercise was 321.1+/-62.0 Nm (PSE) and 295.7+/-72.4 Nm (placebo), and peak power obtained on the 'all-out' 30 s cycle test was 1262.5+/-48.5 W (PSE) and 1228.4+/-47.1 W (placebo) (P<0.01, P<0.03, respectively). Subjects were estimated to be producing 96.9+/-2.4% of their maximal possible isometric leg extension force after PSE ingestion, but only 95.3+/-2.4% when PSE was not ingested. Bench press tasks and total work during the cycle test were not affected by the ingestion of PSE. Lung function was altered following ingestion of PSE (P<0.05) with FEV1 and FVC significantly increased (P<0.02, P<0.01, respectively) although the FEV1/FVC ratio was not altered. Heart rate was significantly elevated by the ingestion of PSE immediately following the 30 s cycle sprint (P<0.01) however, lactate concentration was not altered by the ingestion of PSE. CONCLUSIONS: The administration of a 180 mg dose of PSE increased maximum torque, produced in an isometric knee extension and produced an improvement in peak power during maximal cycle performance, as well as improving lung function.