Tier-specific contextualised high-intensity running profiles in the English Premier League: more on-ball movement at the top.

The present study aimed to determine the physical-tactical profiles of elite football teams and individual players according to final league rankings. A total of 50 English Premier League matches (n = 100 match and 583 player observations) were analysed by coding the player's physical-tactical actions through synchronising tracking data and video. Final league rankings were categorised into Tiers: (A) 1st-5th ranking (n = 25), (B) 6th-10th ranking (n = 26), (C) 11th-15th ranking (n = 26), and (D) 16th-20th ranking (n = 23). One-way analyses of variance were used to compare match performances between different Tiers, and effect size (ES) was determined for the meaningfulness of the difference. Tier A teams covered 39-51% more high-intensity distance for 'Move to Receive/Exploit Space' (ES: 1.3-1.6, P < 0.01) and 'Run with Ball' (ES: 0.9-1.0, P < 0.05) than Tier C and D, and 23-94% more distance for 'Over/Underlap' (ES: 1.0, P < 0.01), 'Run in Behind/Penetrate' (ES: 0.7, P < 0.05), and 'Break into Box' (ES: 0.9, P < 0.05) compared to Tier C. Central and Wide Defensive Players in Tier A covered 65-551% more high-intensity 'Move to Receive/Exploit Space' distance compared to other Tiers (ES: 0.6-1.0, P < 0.01). Moreover, the additional options within the physical-tactical actions and zonal differences unveiled more meaningful insights into 'HOW' the top Tier teams physically and tactically perform. Thus, the amalgamated physical-tactical data help improve our understanding of a team's playing style relative to their competitive standard.

Contextualised high-intensity running profiles of elite football players with reference to general and specialised tactical roles.

The present study aimed to contextualise physical metrics with tactical actions according to general and specialised tactical roles. A total of 244 English Premier League players were analysed by coding player's physical-tactical actions via the fusion of tracking data and video. Data were analysed across 5 general (Central Defensive Players = CDP, Wide Defensive Players = WDP, Central Midfield Players = CMP, Wide Offensive Players = WOP, Central Offensive Players = COP) and 11 specialised positions (Centre Backs = CB, Full-Backs = FB, Wing-Backs = WB, Box-to-Box Midfielders = B2BM, Central Defensive Midfielders = CDM, Central Attacking Midfielders = CAM, Wide Midfielders = WM, Wide Forwards = WF, Centre Forwards = CF). COP covered more distance at high-intensity (> 19.8 km · h-1) when performing actions such as 'Break into Box', Run in Behind/Penetrate', and 'Close Down/Press' than other positions (ES: 0.6-5.2, P < 0.01). WOP covered more high-intensity 'Run with Ball' distance (ES: 0.7-1.7, P < 0.01) whereas WDP performed more 'Over/Underlap' distance than other positions (ES: 0.9-1.4, P < 0.01). CDP and WDP covered more high-intensity 'Covering' distances than other positions (ES: 0.4-2.4, P < 0.01). Nonetheless, data demonstrated that implementing specialised positional analysis relative to a generalised approach is more sensitive in measuring physical-tactical performances of players with the latter over or underestimating the match demands of the players compared to the former. A contextualised analysis may assist coaches and practitioners when designing position or even player-specific training drills since the data provides unique physical-tactical trends across specialised roles.

Contextualised peak periods of play in English Premier League matches.

The present study aimed to determine the physical-tactical trends of elite players/teams during peak 1-, 3- and 5-min periods of match-play. A total of 50 English Premier League matches (n = 583 player observations) were analysed by coding the players' physical-tactical activities through the synchronisation of tracking data and video. The contextualised data showed that during the peak periods (i.e., the most demanding passage of play), players/teams covered the largest distances for 'Recovery Run' (28-37%) out of possession and 'Support Play' (9-13%) in possession. In the following periods, players covered less high-intensity distance versus the average with a more pronounced decline in the next 1-min period than longer duration 3- and 5-min periods (48% vs ~25-30%, ES: 0.4-0.5, P < 0.01); team data showed similar trends with different relative patterns (31% vs 17-30%, ES: 0.5-0.8, P < 0.01). After peak periods, players/teams performed 20-53% less high-intensity distances for 'Covering' and 'Recovery Run' (ES: 0.2-0.7, P < 0.01) out of possession. However, players covered 28-91% less distance for 'Run with Ball' (ES: 0.1-0.5, P < 0.05) when in possession. Some physical-tactical actions exhibited inconsistency in different time durations of the next periods; however, these physical-tactical data were position-specific. This may signify that each position has certain physical-tactical actions to execute even after the peak periods, especially when they are tactically required to do so. As the data demonstrates unique physical-tactical trends of players/teams during the peak and next periods of play, this could help practitioners prescribe position- and player-specific drills, and better understand transient decrements in high-intensity running after intense passages of play.

Science and Hurling: A Review.

Hurling is one of the world's fastest field sports. Since the last review of science and Gaelic sports in 2008, there has been an increase in sports science provisions across elite and sub-elite cohorts, resulting in increased hurling-specific literature equating to an additional 111 research investigations into the game across all sports science disciplines. The present review aims to provide an updated analysis of the current research on the game and propose recommendations for future research. Overall, intermittent aerobic fitness remains an important physical quality during competition, with a focus on games-based training methodologies within the literature. Within the current review, we provide updated normative data on the running demands, physiological responses, and anthropometric and performance profiles of hurling players. The increased literature across the sport has led to the development of a hurling-specific simulation, that can now be utilised practically in training and research processes for hurling cohorts. Furthermore, the monitoring of internal and external training loads across training and match environments, in addition to response variables such as well-being, appears to have become more prominent, allowing practitioners to design training regimes to achieve optimal dose and response characteristics. Analysing the game from a scientific perspective can allow for more efficient preparatory practices, to meet the specific requirements of players at all age levels. Collaborative research among the various sports science disciplines, is required to identify strategies to reduce the incidence of injury and enhance performance in hurling. The current review provides updated information to coaches and practitioners regarding position-specific physical qualities, and match-play demands that can concurrently support the training process within hurling.

The Effects of Pre-Game Carbohydrate Intake on Running Performance and Substrate Utilisation during Simulated Gaelic Football Match Play.

BACKGROUND: Previous research has reported that elite Gaelic football players' carbohydrate (CHO) intakes are sub-optimal, especially, in the lead up to competitive matches. Despite clear decrements in running performance across elite Gaelic football matches, there are no studies that have investigated nutrition interventions on match-related Gaelic football performance. The aim of this study was to determine whether a higher-CHO diet in line with sports nutrition guidelines can improve Gaelic football-related performance compared to lower CHO intakes previously observed in Gaelic footballers. METHODS: Twelve Gaelic football players completed a Gaelic football simulation protocol (GFSP) on two occasions after consuming a high-CHO diet (7 g·kg-1) (HCHO) or an energy-matched lower-CHO diet (3.5 g·kg-1) (L-CHO) for 48 h. Movement demands and heart rate were measured using portable global positioning systems devices. Countermovement jump height (CMJ) and repeated-sprint ability (RSA) were measured throughout each trial. Expired respiratory gases were collected throughout the trial using a portable gas analyser. Blood samples were taken at rest, half-time, and post-simulation. RESULTS: There was no significant difference in total distance (p = 0.811; η2 = 0.005) or high-speed running distance (HSRD) covered between both trials. However, in the second half of the HCHO trial, HSRD was significantly greater compared to the second half of the LCHO trial (p = 0.015). Sprint distance covered during GFSP was significantly greater in HCHO (8.1 ± 3.5 m·min-1) compared with LCHO (6.4 ± 3.2 m·min-1) (p = 0.011; η2 = 0.445). RSA performance (p < 0.0001; η2 = 0.735) and lower body power (CMJ) (p < 0.0001; η2 = 0.683) were significantly greater during the HCHO trial compared to LCHO. Overall CHO oxidation rates were significantly greater under HCHO conditions compared to LCHO (3.3 ± 0.5 vs. 2.7 ± 0.6 g·min-1) (p < 0.001; η2 = 0.798). Blood lactate concentrations were significantly higher during HCHO trial versus LCHO (p = 0.026; η2 = 0.375). There were no significant differences in plasma glucose, non-esterified fatty acids (NEFAs), and glycerol concentration between trials. In both trials, all blood metabolites were significantly elevated at half-time and post-trial compared to pre-trial. CONCLUSION: These findings indicate that a higher-CHO diet can reduce declines in physical performance during simulated Gaelic football match play.

Understanding the association between external training load measures and injury risk in Elite Gaelic football.

BACKGROUND: The current investigation examined the association between external training load variables and injury risk within elite Gaelic football. METHODS: Workload and injury variables were collected from thirty-seven elite Gaelic footballers (mean±SD age of 24.2±2.9 years) from one elite squad across a two-season observational period. External training load variables included total distance (m), High speed running (m; ≥17.1 km·h-1), Sprint distance (m; 22 km·h-1), Accelerations (n), Average metabolic power (W·kg-1), high-power distance (m; ≥25 W·kg-1). Cumulative 1- weekly, 2-weekly, 3-weekly and 4-weekly training loads; acute: chronic workload ratio (ACWR) was analysed across specific distributions of low, moderate and high loading with respect to a reference group of the measure quantified. General estimating equations were utilized to understand the association of these variables with injury risk. RESULTS: Strong associations (AUC>0.50) were observed amongst models developed for one weekly loading for relative distance, average metabolic power and high-power indices with similar trends observed for two, three and four weekly which showed a strong positive association within injury risk for all external loading metrics (AUC>0.50), with average metabolic power, and high-power distance showing the strongest association across the three-four week loading scales (AUC>0.60). When the ACWR was considered for external load measures these showed a positive linear association with injury risk (AUC>0.50). When intensity measures were considered relative distance showed an associated risk for injury across one and two-weekly models but not three and four weekly models. When odds risk association was considered a consistent trend towards moderate loading across external loading measures was apparent within the observed cohort. CONCLUSIONS: The current investigation reports for the first time the injury association for external loading measures within elite Gaelic football. Data show that a range of measures are associated with increased or decreased injury risk depending on the loading scheme applied by coaches within elite Gaelic football.

Rethinking training in elite soccer players: comparative evidence of small-sided games and official match play in kinematic parameters.

BACKGROUND: The aim of this study was to compare kinematics parameters among official matches and SSGs of an Italian premier league soccer team. METHODS: Eighteen elite professional male soccer players (4 central defenders, 4 wide defenders, 3 central midfielders, 3 box-to-box midfielders, 2 wingers and 2 strikers) took part in the study. Players were monitored during four months of full training (including preseason and in-season) and over 26 matches (14 Serie A matches, 9 Europa League matches, and 3 friendly matches), from July 2017 until November 2017. The kinematic parameters during official matches and SSGs were evaluated through video match analysis. RESULTS: The kinematic data analysis shows that the metabolic power, that constitutes an integrated measure of acceleration and velocity, fails to reflect what occurs during actual match-play. CONCLUSIONS: An increased attention should be place in planning SSGs during training to better reproduce actual match situations.

Addition of Caffeine to a Carbohydrate Feeding Strategy Prior to Intermittent Exercise.

The ergogenic effect of caffeine is well established, although no investigations providing a high carbohydrate feeding strategy (pre-exercise meal=2 g/kg BM) co-ingested with caffeine exist for soccer. This investigation examines the effect of caffeine in addition to a pre-exercise carbohydrate meal and drink mid-way through a soccer simulation. Eight recreational soccer players completed an 85-minute soccer simulation followed by an exercise capacity test (Yo-yo Intermittent Endurance test level 2) on two occasions. Prior to exercise participants consumed a high carbohydrate meal, with placebo or 5 mg/kg BM-1 caffeine. No significant performance effect was identified (p=0.099) despite a 12.8% (109 m) improvement in exercise capacity following caffeine. Rates of carbohydrate and fat oxidation did not differ between conditions and nor were differences apparent for plasma glucose, fatty acids, glycerol, ß-hydroxybutyrate (p>0.05). However, an increase in lactate was observed for caffeine (p=0.039). A significant condition effect on rating of perceived exertion was identified (p<0.001), with the overall mean for the protocol lowered to 11.7±0.9 au for caffeine compared to 12.8±1.3 au. Caffeine supplementation with a carbohydrate feeding strategy failed to affect metabolic and metabolite responses, although reductions in perception of exercise were observed. While a 12.8% increase in exercise capacity was noted the findings were not significant, possibly due to the small sample size.

Probiotic supplementation increases carbohydrate metabolism in trained male cyclists: a randomized, double-blind, placebo-controlled crossover trial.

We hypothesized that probiotic supplementation (PRO) increases the absorption and oxidation of orally ingested maltodextrin during 2 h endurance cycling, thereby sparing muscle glycogen for a subsequent time trial (simulating a road race). Measurements were made of lipid and carbohydrate oxidation, plasma metabolites and insulin, gastrointestinal (GI) permeability, and subjective symptoms of discomfort. Seven male cyclists were randomized to PRO (bacterial composition given in methods) or placebo for 4 wk, separated by a 14-day washout period. After each period, cyclists consumed a 10% maltodextrin solution (initial 8 mL/kg bolus and 2 mL/kg every 15 min) while exercising for 2 h at 55% maximal aerobic power output, followed by a 100-kJ time trial. PRO resulted in small increases in peak oxidation rates of the ingested maltodextrin (0.84 ± 0.10 vs. 0.77 ± 0.09 g/min; P = 0.016) and mean total carbohydrate oxidation (2.20 ± 0.25 vs. 1.87 ± 0.39 g/min; P = 0.038), whereas fat oxidation was reduced (0.40 ± 0.11 vs. 0.55 ± 0.10 g/min; P = 0.021). During PRO, small but significant increases were seen in glucose absorption, plasma glucose, and insulin concentration and decreases in nonesterified fatty acid and glycerol. Differences between markers of GI damage and permeability and time-trial performance were not significant (P > 0.05). In contrast to the hypothesis, PRO led to minimal increases in absorption and oxidation of the ingested maltodextrin and small reductions in fat oxidation, whereas having no effect on subsequent time-trial performance.

The Validity of an Updated Metabolic Power Algorithm Based upon di Prampero's Theoretical Model in Elite Soccer Players.

The aim of this study was to update the metabolic power (MP) algorithm (PV˙O2, W·kg-1) related to the kinematics data (PGPS, W·kg-1) in a soccer-specific performance model. For this aim, seventeen professional (Serie A) male soccer players (V˙O2max 55.7 ± 3.4 mL·min-1·kg-1) performed a 6 min run at 10.29 km·h-1 to determine linear-running energy cost (Cr). On a separate day, thirteen also performed an 8 min soccer-specific intermittent exercise protocol. For both procedures, a portable Cosmed K4b2 gas-analyzer and GPS (10 Hz) was used to assess the energy cost above resting (C). From this aim, the MP was estimated through a newly derived C equation (PGPSn) and compared with both the commonly used (PGPSo) equation and direct measurement (PV˙O2). Both PGPSn and PGPSo correlated with PV˙O2 (r = 0.66, p < 0.05). Estimates of fixed bias were negligible (PGPSn = -0.80 W·kg-1 and PGPSo = -1.59 W·kg-1), and the bounds of the 95% CIs show that they were not statistically significant from 0. Proportional bias estimates were negligible (absolute differences from one being 0.03 W·kg-1 for PGPSn and 0.01 W·kg-1 for PGPSo) and not statistically significant as both 95% CIs span 1. All variables were distributed around the line of unity and resulted in an under- or overestimation of PGPSn, while PGPSo routinely underestimated MP across ranges. Repeated-measures ANOVA showed differences over MP conditions (F1,38 = 16.929 and p < 0.001). Following Bonferroni post hoc test significant differences regarding the MP between PGPSo and PV˙O2/PGPSn (p < 0.001) were established, while no differences were found between PV˙O2 and PGPSn (p = 0.853). The new approach showed it can help the coaches and the soccer trainers to better monitor external training load during the training seasons.

Time-of-day variation on performance measures in repeated-sprint tests: a systematic review.

The lack of standardization of methods and procedures have hindered agreement in the literature related to time-of-day effects on repeated sprint performance and needs clarification. Therefore, the aim of the present study was to investigate and systematically review the evidence relating to time-of-day based on performance measures in repeated-sprints.The entire content of PubMed (MEDLINE), Scopus, SPORTDiscus® (via EBSCOhost) and Web of Science was searched. Only experimental research studies conducted in male adult participants aged ≥18yrs, published in English before June 2019 were included. Studies assessing repeated-sprints between a minimum of two time-points during the day (morning versus evening) were deemed eligible.The primary search revealed that a total of 10 out of 112 articles were considered eligible and subsequently included. Seven articles were deemed strong and three moderate quality. Eight studies found repeated-sprint performance across the first, first few, or all sprints, to increase in favor of the evening. The magnitude of difference is dependent on the modality and the exercise protocol used. The non-motorized treadmill established an average 3.5-8.5% difference in distance covered, average and peak velocity, and average power, across all sprints in three studies and in peak power in two studies. In cycling, power output differed across all sprints by 6.0% in one study and 8.0% for the first sprint only in five studies. All four studies measuring power decrement values (i.e. rate of fatigue) established differences up to 4.0% and two out of five studies established total work to be significantly higher by 8.0%.Repeated-sprint performance is affected by time-of-day with greater performance in the late/early afternoon. The magnitude is dependent on the variable assessed and the mode of exercise. There is a clear demand for more rigorous investigations which control factors that specifically relate to investigations of time-of-day and are specific to the sport of individuals.

Four weeks of probiotic supplementation reduces GI symptoms during a marathon race.

PURPOSE: To evaluate the effects of probiotic supplementation on gastrointestinal (GI) symptoms, circulatory markers of GI permeability, damage, and markers of immune response during a marathon race. METHODS: Twenty-four recreational runners were randomly assigned to either supplement with a probiotic (PRO) capsule [25 billion CFU Lactobacillus acidophilus (CUL60 and CUL21), Bifidobacterium bifidum (CUL20), and Bifidobacterium animalis subs p. Lactis (CUL34)] or placebo (PLC) for 28 days prior to a marathon race. GI symptoms were recorded during the supplement period and during the race. Serum lactulose:rhamnose ratio, and plasma intestinal-fatty acid binding protein, sCD14, and cytokines were measured pre- and post-races. RESULTS: Prevalence of moderate GI symptoms reported were lower during the third and fourth weeks of the supplement period compared to the first and second weeks in PRO (p < 0.05) but not PLC (p > 0.05). During the marathon, GI symptom severity during the final third was significantly lower in PRO compared to PLC (p = 0.010). The lower symptom severity was associated with a significant difference in reduction of average speed from the first to the last third of the race between PLC (- 14.2 ± 5.8%) and PRO (- 7.9 ± 7.5%) (p = 0.04), although there was no difference in finish times between groups (p > 0.05). Circulatory measures increased to a similar extent between PRO and PLC (p > 0.05). CONCLUSION: Probiotics supplementation was associated with a lower incidence and severity of GI symptoms in marathon runners, although the exact mechanisms are yet to be elucidated. Reducing GI symptoms during marathon running may help maintain running pace during the latter stages of racing.

Dietary Intake and Energy Expenditure Assessed during a Pre-Season Period in Elite Gaelic Football Players.

There is currently a lack of research into the energy demands and associated nutritional intakes of elite Gaelic football players during the pre-season period, which is a crucial time of year for physical development. The aim of the current study was to investigate the dietary intake and energy expenditure (EE) of elite Gaelic football players during a typical pre-season week. Over a seven-day period, which included four training days and three rest days, dietary intake (validated self-reported estimated food diary) and EE (Sensewear Pro armband) were recorded in 18 male players from a single elite inter-county Gaelic football team. Average energy intake (EI) (3283 ± 483 kcal) was significantly (p = 0.002) less than average EE (3743 ± 335 kcal), with a mean daily energy deficit of -460 ± 503 kcal. Training days elicited the greatest deficits between intake and expenditure. The mean carbohydrate (CHO) intake was 3.6 ± 0.7 g/kg/day, protein intake was 2.1 ± 0.5 g/kg/day, and fat intake was 1.6 ± 0.2 g/kg/day. These findings indicate that the dietary practices of the sampled players were inadequate to meet EE and CHO recommendations. Training days are of particular concern, with the players not altering energy and CHO intake to encounter increased energy demands. Education on nutritional strategies for elite Gaelic footballers should be considered in relation to training demands to avoid detriments to performance and health.

Can the workload-injury relationship be moderated by improved strength, speed and repeated-sprint qualities?

OBJECTIVES: The aim of this study was to investigate potential moderators (i.e. lower body strength, repeated-sprint ability [RSA] and maximal velocity) of injury risk within a team-sport cohort. DESIGN: Observational cohort study. METHODS: Forty male amateur hurling players (age: 26.2±4.4 year, height: 184.2±7.1cm, mass: 82.6±4.7kg) were recruited. During a two-year period, workload (session RPE×duration), injury and physical qualities were assessed. Specific physical qualities assessed were a three-repetition maximum Trapbar deadlift, 6×35-m repeated-sprint (RSA) and 5-, 10- and 20-m sprint time. All derived workload and physical quality measures were modelled against injury data using regression analysis. Odds ratios (OR) were reported against a reference group. RESULTS: Moderate weekly loads between ≥1400 AU and ≤1900 AU were protective against injury during both the pre-season (OR: 0.44, 95% CI: 0.18-0.66) and in-season periods (OR: 0.59, 95% CI: 0.37-0.82) compared to a low load reference group (≤1200 AU). When strength was considered as a moderator of injury risk, stronger athletes were better able to tolerate the given workload at a reduced risk. Stronger athletes were also better able to tolerate larger week-to-week changes (>550-1000 AU) in workload than weaker athletes (OR=2.54-4.52). Athletes who were slower over 5-m (OR: 3.11, 95% CI: 2.33-3.87), 10-m (OR: 3.45, 95% CI: 2.11-4.13) and 20-m (OR: 3.12, 95% CI: 2.11-4.13) were at increased risk of injury compared to faster athletes. When repeated-sprint total time (RSAt) was considered as a moderator of injury risk at a given workload (≥1750 AU), athletes with better RSAt were at reduced risk compared to those with poor RSAt (OR: 5.55, 95%: 3.98-7.94). CONCLUSIONS: These findings demonstrate that well-developed lower-body strength, RSA and speed are associated with better tolerance to higher workloads and reduced risk of injury in team-sport athletes.

Carbohydrate oxidation and glucose utilisation under hyperglycaemia in aged and young males during exercise at the same relative exercise intensity.

PURPOSE: The purpose of the present study was to investigate the age-related carbohydrate oxidation and glucose utilisation rate response during exercise at the same relative intensity under hyperglycaemia in aged and young males. METHODS: 16 endurance-trained aged (n = 8; 69.1 ± 5.2 year) and young (n = 8; 22.4 ± 2.9 year) males were studied during 40 min of cycling exercise (60% [Formula: see text]) under both hyperglycaemic and euglycaemic (control) conditions. Venous blood samples were collected at baseline, post-infusion, mid- and post-exercise. Carbohydrate and fat oxidation rates were determined at both 15 and 35 min during exercise, and glucose utilisation rates were calculated. RESULTS: The aged group displayed significantly lower rates of carbohydrate oxidation during exercise during maintained hyperglycemia (15 min = 2.3 ± 0.4 vs. 1.6 ± 0.5 g min-1; 35 min = 2.3 ± 0.5 vs. 1.5 ± 0.5 g min-1) and control (15 min = 2.2 ± 0.4 vs. 1.6 ± 0.7 g min-1; 35 min = 1.9 ± 0.7 vs. 1.3 ± 0.7 g min-1) conditions (P = 0.01). The rate of glucose utilisation during exercise was also significantly reduced (85.76 ± 23.95 vs. 56.67 ± 15.09 µM kg-1 min-1). There were no differences between age groups for anthropometric measures, fat oxidation, insulin, glucose, NEFA, glycerol and lactate (P > 0.05) although hyperglycemia resulted in elevated glucose and insulin, and attenuated fat metabolite levels. CONCLUSION: Our findings highlight that ageing results in a reduction in carbohydrate oxidation and utilisation rates during exercise at the same relative exercise intensity.

Controlling rectal and muscle temperatures: Can we offset diurnal variation in repeated sprint performance?

The present study investigated whether increasing morning rectal temperatures (Trec) to resting.evening levels, or decreasing evening Trec or muscle (Tm) temperatures to morning values, would influence repeated sprint (RS) performance in a causal manner. Twelve trained males underwent five sessions [age (mean ± SD) 21.8 ± 2.6 yr, peak oxygen uptake ([Formula: see text] peak) 60.6 ± 4.6 mL kg min-1, stature 1.78 ± 0.07 m and body mass 76.0 ± 6.3 kg]. These included a control morning (M, 07:30 h) and evening (E, 17:30 h) session (5-min warm-up), and three further sessions consisting of a warm-up morning trial (ME, on a motorised treadmill) until Trec reached evening levels; and two cool-down evening trials (in 16-17°C water) until Trec (EMrec) or Tm (EMmuscle) values reached morning temperatures, respectively. All sessions included a 3 × 3-s task-specific warm-up followed by 10 × 3-s RS with 30-s recoveries performed on a non-motorised treadmill. Trec and Tm measurements were taken at the start of the protocol and following the warm-up or cool-down period. Values for Trec and Tm were higher in the evening compared to morning values (0.45°C and 0.57°C, P < 0.05). RS performance was lower in the M for distance covered (DC), average power (AP) and average velocity (AV) (9-10%, P < 0.05). Pre-cooling Trec and Tm in the evening reduced RS performance to levels observed in the morning (P < 0.05). However, an active warm-up resulted in no changes in morning RS performance. Diurnal variation in Trec and Tm is not wholly accountable for time-of-day oscillations in RS performance on a non-motorised treadmill; the exact mechanism(s) for a causal link between central temperature and human performance are still unclear and require more research.

Diurnal variation in repeated sprint performance cannot be offset when rectal and muscle temperatures are at optimal levels (38.5°C).

The present study investigated whether increasing morning rectal temperatures (Trec) to evening levels, or increasing morning and evening Trec to an "optimal" level (38.5°C), resulting in increased muscle temperatures (Tm), would offset diurnal variation in repeated sprint (RS) performance in a causal manner. Twelve trained males underwent five sessions [age (mean ± SD) 21.0 ± 2.3 years, maximal oxygen consumption (V̇O2max) 60.0 ± 4.4 mL.kg-1 min-1, height 1.79 ± 0.06 m, body mass 78.2 ± 11.8 kg]. These included control morning (M, 07:30 h) and evening (E, 17:30 h) sessions (5-min warm-up), and three further sessions consisting of a warm-up morning trial (ME, in 39-40°C water) until Trec reached evening levels; two "optimal" trials in the morning and evening (M38.5 and E38.5, in 39-40°C water) respectively, until Trec reached 38.5°C. All sessions included 3 × 3-s task-specific warm-up sprints, thereafter 10 × 3-s RS with 30-s recoveries were performed a non-motorised treadmill. Trec and Tm measurements were taken at the start of the protocol and following the warm-up periods. Values for Trec and Tm at rest were higher in the evening compared to morning values (0.48°C and 0.69°C, p < 0.0005). RS performance was lower (7.8-8.3%) in the M for distance covered (DC; p = 0.002), average power (AP; p = 0.029) and average velocity (AV; p = 0.002). Increasing Trec in the morning to evening values or optimal values (38.5°C) did not increase RS performance to evening levels (p = 1.000). However, increasing Trec in the evening to "optimal" level through a passive warm-up significantly reduced DC (p = 0.008), AP (p < 0.0005) and AV (p = 0.007) to values found in the M condition (6.0-6.9%). Diurnal variation in Trec and Tm is not wholly accountable for time-of-day oscillations in RS performance on a non-motorised treadmill; the exact mechanism(s) for a causal link between central temperature and human performance are still unclear and require more research.

The Work-Rate of Elite Hurling Match-Play.

Collins, DK, McRobert, A, Morton, JP, O'Sullivan, D, and Doran, DA. The work-rate of elite hurling match-play. J Strength Cond Res 32(3): 805-811, 2018-This study describes the global work-rate of elite hurling match-play and the influence which positional difference has on work-rate is considered. The movement of ninety-four players was recorded using global positioning system, sampling at 4 Hz in a total of 12 games. Data were classified according to the positional line on the field and period of the match. The total and high-speed distance of match-play was 7,617 ± 1,219 m (95% confidence interval [CI], 7,367-7,866) and 1,134 ± 358 m (95% CI, 1,060-1,206), respectively. The maximum speed attained was 29.8 ± 2.3 km·h with a mean speed of 6.1 ± 1 km·h. The second {271 ± 107 m (p = 0.001; effect size [ES] = 0.25)}, third (278 ± 118 m [p = 0.001; ES = 0.21]), and fourth quarter (255 ± 108 m [p = 0.001; ES = 0.31]) high-speed running distance differed significantly from that of the first quarter (330 ± 120 m). There was a significant difference in total (p = 0.001; ES = 0.01-0.85), high-speed running (p = 0.001; ES = 0.21-0.76), and sprint (p = 0.013; ES = 0.01-0.39) distance across the positions, with midfielders undertaking the highest volume of work, followed by the half-forward and half-back lines and finally the full-forward and full-back lines. A decrease in high-speed running distance seems to occur through out the game and in particular at the latter stages of each half. Distinct positional work profiles are evident. The present finding provide a context on which training which replicates the work-rate of match-play may be formulated, thus helping to improve the physical preparation of elite players.

Glutamine supplementation reduces markers of intestinal permeability during running in the heat in a dose-dependent manner.

PURPOSE: To examine the dose-response effects of acute glutamine supplementation on markers of gastrointestinal (GI) permeability, damage and, secondary, subjective symptoms of GI discomfort in response to running in the heat. METHODS: Ten recreationally active males completed a total of four exercise trials; a placebo trial and three glutamine trials at 0.25, 0.5 and 0.9 g kg-1 of fat-free mass (FFM) consumed 2 h before exercise. Each exercise trial consisted of a 60-min treadmill run at 70% of [Formula: see text] in an environmental chamber set at 30 °C. GI permeability was measured using ratio of lactulose to rhamnose (L:R) in serum. Plasma glutamine and intestinal fatty acid binding protein (I-FABP) concentrations were determined pre and post exercise. Subjective GI symptoms were assessed 45 min and 24 h post-exercise. RESULTS: Relative to placebo, L:R was likely lower following 0.25 g kg-1 (mean difference: - 0.023; ± 0.021) and 0.5 g kg-1 (- 0.019; ± 0.019) and very likely following 0.9 g kg- 1 (- 0.034; ± 0.024). GI symptoms were typically low and there was no effect of supplementation. DISCUSSION: Acute oral glutamine consumption attenuates GI permeability relative to placebo even at lower doses of 0.25 g kg-1, although larger doses may be more effective. It remains unclear if this will lead to reductions in GI symptoms. Athletes competing in the heat may, therefore, benefit from acute glutamine supplementation prior to exercise in order to maintain gastrointestinal integrity.