• Beetroot supplementation improves the physiological responses to incline walking

      Waldron, Mark; Waldron, Luke; Lawlor, Craig; Gray, Adrian; Highton, Jamie M.; St Mary's University; University of New England; Medical Education Centre Royal Cornwall Hospitals NHS Trust; University of Chester (Springer, 2018-03-15)
      Purpose: We investigated the effects of an acute 24-h nitrate-rich beetroot juice supplement (BR) on the energy cost, exercise efficiency and blood pressure responses to intermittent walking at different gradients. Methods: In a double-blind, cross-over design, eight participants were provided with a total of 350 ml of nitrate-rich (~20.5 mmol nitrate) BR or placebo (PLA) across 24-h before completing intermittent walking at 3 km/h on treadmill at gradients of 1%, 5%, 10%, 15% and 20%. Results: Resting mean arterial pressure (MAP) was ~4.1% lower after BR (93 vs. 89 mmHg; P = 0.001), as well as during exercise (102 vs. 99 mmHg; P = 0.011) and recovery (97 vs. 94 mmHg; P = 0.001). Exercising (1227 vs. 1129 ml/min P < 0.001) and end-stage (1404 vs. 1249 ml/min; P = 0.002) oxygen uptake (𝑉O2) was lower in BR compared to PLA, which was accompanied by an average reduction in phase II 𝑉 ̇O2 amplitude (1067 vs. 940 ml/min; P = 0.025). Similarly, recovery 𝑉O2 (509 vs. 458 ml/min; P = 0.001) was lower in BR. Whole-blood potassium concentration increased from pre-post exercise in PLA (4.1 ± 0.3 vs. 4.5 ± 0.3 mmol/L; P = 0.013) but not BR (4.1 ± 0.31 vs. 4.3 ± 0.2 mmol/L; P = 0.188). Conclusions: Energy cost of exercise, recovery of 𝑉O2, MAP and blood markers were ameliorated after BR. Previously reported mechanisms explain these findings, which are more noticeable during less efficient walking at steep gradients (15-20%). These findings have practical implications for hill-walkers.
    • Carbohydrate and caffeine improves high intensity running of elite rugby league interchange players during simulated match play

      Clarke, Jon; Highton, Jamie M.; Close, Graeme L.; Twist, Craig; University of Chester; Warrington Wolves RLFC; Liverpool John Moores University (Lippincott, Williams & Wilkins, 2016-11-19)
      Carbohydrate and caffeine improves high intensity running of elite rugby league interchange players during simulated match play
    • Carbohydrate-protein ingestion during self-regulated simulated multiple-sprint sport activity

      Highton, Jamie M.; Nicholas, Ceri; Twist, Craig; Lamb, Kevin L.; University of Chester (2011-09)
    • The concurrent validity of a rugby-specific Yo-Yo Intermittent Recovery Test (Level 1) for assessing match-related running performance

      Dobbin, Nick; Highton, Jamie M.; Moss, Samantha L.; Hunwicks, Richard; Twist, Craig; University of Chester; Rugby Football League, Leeds (Lippincott, Williams & Wilkins, 2018-06-01)
      This study investigated the concurrent validity of a rugby-specific high-intensity intermittent running test (HIIR) against the internal, external and perceptual responses to simulated match-play. Thirty-six rugby league players (age 18.5 ± 1.8 years; stature 181.4 ± 7.6 cm; body mass 83.5 ± 9.8 kg) completed the prone Yo-Yo IR1, of which sixteen also completed the Yo-Yo IR1, and 2 x ~20 min bouts of a simulated match-play (RLMSP-i). Most likely reductions in relative total, low-speed and high-speed distance, mean speed and time above 20 W·kg-1 (HMP) were observed between bouts of the RLMSP-i. Likewise, rating of perceived exertion (RPE) and percentage of peak heart rate (%HRpeak) were very likely and likely higher during the second bout. Pearson’s correlations revealed a large relationship for the change in relative distance (r = 0.57-0.61) between bouts with both Yo-Yo IR1 tests. The prone Yo-Yo IR1 was more strongly related to the RLMSP-i for change in repeated sprint speed (r = 0.78 cf. 0.56), mean speed (r = 0.64 cf. 0.36), HMP (r = 0.48 cf. 0.25), fatigue index (r = 0.71 cf. 0.63), %HRpeak (r = -0.56 cf. -0.35), RPEbout1 (r = -0.44 cf. -0.14), and RPEbout2 (r = -0.68 cf. -0.41) than the Yo-Yo IR1, but not for blood lactate concentration (r = -0.20 to -0.28 cf. -0.35 to -0.49). The relationships between prone Yo-Yo IR1 distance and measure of load during the RLMSP-i suggests it possesses concurrent validity and is more strongly associated with measures of training or match load than the Yo-Yo IR1 using rugby league players.
    • Criterion and construct validity of an isometric mid-thigh pull dynamometer for assessing whole body strength in professional rugby league players

      Dobbin, Nicholas; Hunwicks, Richard; Jones, Ben; Till, Kevin; Highton, Jamie M.; Twist, Craig; University of Chester, Rugby Football League, Leeds Beckett University (Human Kinetics, 2018-02-31)
      Purpose: The purpose of this study was to examine the criterion and construct validity of an isometric mid-thigh pull dynamometer to assess whole body strength in professional rugby league players. Methods: Fifty-six male rugby league players, (33 senior and 23 youth professional players) performed four isometric mid-thigh pull efforts (i.e. two on the dynamometer and two on the force platform) in a randomised and counterbalanced order. Results: Isometric peak force was underestimated (P<0.05) using the dynamometer compared to the force platform (95% LoA: -213.5 ± 342.6 N). Linear regression showed that peak force derived from the dynamometer explained 85% (adjusted R2 = 0.85, SEE = 173 N) of the variance in the dependent variable, with the following prediction equation derived: predicted peak force = [1.046 * dynamometer peak force] + 117.594. Cross-validation revealed a non-significant bias (P>0.05) between the predicted and peak force from the force platform, and an adjusted R2 (79.6%), that represented shrinkage of 0.4% relative to the cross-validation model (80%). Peak force was greater for the senior compared to youth professionals using the dynamometer (2261.2 ± 222 cf. 1725.1 ± 298.0 N, respectively; P<0.05). Conclusion: The isometric mid-thigh pull assessed using a dynamometer underestimates criterion peak force but is capable of distinguishing muscle function characteristics between professional rugby league players of different standards.
    • The discriminant validity of standardised testing battery and its ability to differentiate anthropometric and physical characteristics between youth, academy and senior professional rugby league players

      Dobbin, Nicholas; Moss, Samantha L.; Highton, Jamie M.; Twist, Craig; University of Chester (Human Kinetics, 2019-01-31)
      Purpose: To assess a standardised testing battery’s ability to differentiate anthropometric and physical qualities between youth, academy and senior rugby league players, and determine the discriminant validity of the battery. Methods: A total of 729 rugby league players from multiple clubs within England categorised as youth (n = 235), academy (n = 362) and senior (n = 132) players completed a standardised testing battery that included the assessment of anthropometric and physical characteristics during preseason. Data was analysed using magnitude-based inferences and discriminant analysis. Results: Academy players were most likely taller and heavier than youth players (effect size (ES) = 0.64 to 1.21), with possibly to most likely superior CMJ, medicine ball throw and prone Yo-Yo IR1 performance (ES = 0.23 to 1.00). Senior players were likely to most likely taller and heavier (ES = 0.32 to 1.84), with possibly to most likely superior 10 and 20 m sprint times, CMJ, CoD, medicine ball throw and prone Yo-Yo IR1 compared to youth and academy (ES = -0.60 to 2.06). The magnitude of difference appeared to be influenced by playing position. For the most part, the battery possessed discriminant validity with an accuracy of 72.2%. Conclusion: The standardised testing battery differentiates anthropometric and physical qualities of youth, academy and senior players as a group and, in most instances, within positional groups. Furthermore, the battery is able to discriminate between playing standards with good accuracy and might be included in future assessments and rugby league talent identification.
    • The effect of carbohydrate-protein ingestion on simulated multiple-sprint sport performance

      Highton, Jamie M.; Nicholas, Ceri; Twist, Craig; Lamb, Kevin L.; University of Chester (2011-04)
    • The effects of a carbohydrate-protein beverage on muscle function and performance following simulated multiple-sprint sport activity

      Highton, Jamie M.; Nicholas, Ceri; Twist, Craig; Lamb, Kevin L.; University of Chester (2010-09)
    • The effects of in-season, low-volume sprint interval training with and without sport-specific actions on the physical characteristics of elite academy rugby league players

      Dobbin, Nick; Highton, Jamie M.; Moss, Samantha; Twist, Craig (Human Kinetics, 2020-05-01)
      Purpose: To determine the utility of a running and rugby-specific, in-season sprint interval interventions in professional rugby league players. Methods: Thirty-one professional academy rugby players were assigned to a rugby-specific (SITr/s, n = 16) or running (SITr, n = 15) sprint interval training group. Measures of speed, power, change of direction (CoD) ability, prone Yo-Yo IR1 performance and heart rate recovery (HRR) were taken before and after the 2-week intervention as were sub-maximal responses to the prone Yo-Yo IR1. Internal, external and perceptual responses were collected during SITr/s/SITr, with wellbeing and neuromuscular function assessed before each session. Results: Despite contrasting (possible to most likely) internal, external and perceptual responses to the SIT interventions, possible to most likely within-group improvements in physical characteristics, HRR and sub-maximal responses to the prone Yo-Yo IR1 were observed after both interventions. Between-group analysis favoured the SITr/s intervention (trivial to moderate) for changes in 10 m sprint time, CMJ, change of direction and medicine ball throw as well as sub-maximal (280-440 m) high metabolic power, PlayerLoad™ and acceleratory distance during the prone Yo-Yo IR1. Overall changes in wellbeing or neuromuscular function were unclear. Conclusion: Two-weeks of SITr/s and SITr was effective for improving physical characteristics, HRR and sub-maximal responses to the prone Yo-Yo IR1, with no clear change in wellbeing and neuromuscular function. Between-group analysis favoured the SITr/s group, suggesting that the inclusion of sport- specific actions should be considered for in-season conditioning of rugby league players.
    • The effects of physical contact type on the internal and external demands during a rugby league match simulation protocol.

      Norris, Jonathan; Highton, Jamie M.; Hughes, Stephen F.; Twist, Craig; University of Chester (Taylor and Francis, 2016-02-09)
      This study investigated how the type of contact influences physiological, perceptual and locomotive demands during a simulated rugby league match. Eleven male university rugby league players performed two trials of the rugby league movement simulation protocol for forwards (RLMSP-i) with a traditional soft tackle bag (BAG) and a weighted tackle sled (SLED) to replicate contact demands. Locomotive rate, sprint speed, tackle intensity, heart rate, rating of perceived exertion and blood lactate concentration were analysed in four periods during the first and second bout of both trials. Countermovement jump (CMJ) was measured before and immediately after each trial. More time was spent in heart rate zone between 90 – 100% HRpeak during the first (effect size ± 95% confidence interval: 0.44 ± 0.49) and second bout (0.44 ± 0.43), and larger (0.6 ± 0.69) decrements in CMJ performance were observed during SLED (5.9, s = 4.9%) compared to BAG (2.6, s = 5.4%). Sprint into contact speed was faster during BAG compared to SLED in the first (1.10 ± 0.92) and second bout (0.90 ± 0.90), which impaired high intensity running ability but did not increase physiological strain. Changing the type of contact during the match simulation subtly altered both the internal and external load on participants. These findings indicate that tackle training apparatus should be considered regarding the outcome of a training session.
    • Energy expenditure, metabolic power and high speed activity during linear and multi-directional running

      Oxendale, Chelsea; Highton, Jamie M.; Twist, Craig; University of Chester (Elsevier, 2017-03-21)
      Objectives: The purpose of the study was to compare measures of energy expenditure derived from indirect calorimetry and micro-technology, as well as high power and high speed activity during linear and multi-directional running. Design: Repeated measures Methods: Twelve university standard team sport players completed a linear and multi-directional running condition. Estimated energy expenditure, as well as time at high speed (> 14.4 km.h-1) and high power (> 20 W.kg-1) were quantified using a 10 Hz micro-technology device and compared with energy expenditure derived from indirect calorimetry. Results: Measured energy expenditure was higher during the multi-directional condition (9.0 ± 2.0 cf. 5.9 ± 1.4 kcal.min-1), whereas estimated energy expenditure was higher during the linear condition (8.7 ± 2.1 cf. 6.5 ± 1.5 kcal.min-1). Whilst measures of energy expenditure were strongly related (r > 0.89, p < 0.001), metabolic power underestimated energy expenditure by 52% (95% LoA: 20-93%) and 34% (95% LoA: 12-59%) during the multi-directional and linear condition, respectively. Time at high power was 41% (95% LoA: 4-92%) greater than time at high speed during the multi-directional condition, whereas time at high power was 5% (95% LoA: -17-9%) lower than time at high speed during the linear condition. Conclusions: Estimated energy expenditure and time at high metabolic power can reflect changes in internal load. However, micro-technology cannot be used to determine the energy cost of intermittent running.
    • An examination of a modified Yo-Yo test to measure intermittent running performance in rugby players

      Dobbin, Nick; Moss, Samantha; Highton, Jamie M.; Twist, Craig; University of Chester; University of Chester (Taylor & Francis, 2018-06-17)
      This study examined how starting each shuttle in the prone position altered the internal, external and perceptual responses to the Yo-Yo Intermittent Recovery Test Level 1. Using a randomized crossover design, 17 male rugby players completed the Yo-Yo IR1 and prone Yo-Yo IR1 on two separate occasions. External loads (via microtechnology), V ̇O2, heart rate (HR), rating of perceived exertion (RPE) were measured at 160, 280 and 440 m (sub-maximal) and when the test was terminated (peak). The pre-to-post change in blood lactate concentration (∆[La]b) was determined for both tests. All data were analysed using effect sizes and magnitude-based inferences. Between-trial differences (ES  90%CL) indicated total distance was most likely lower (-1.87  0.19), whereas other measures of peak external load were likely to very likely higher during the prone Yo-Yo IR1 (0.62-1.80). Sub-maximal RPE was likely to most likely higher (0.40-0.96) and peak RPE very likely higher (0.63  0.41) in the prone Yo-Yo IR1. The change in [La]b was likely higher after the prone Yo-Yo IRl. Mean HR was possibly lower at 440 m (-0.25  0.29) as was peak HR (-0.26  0.25) in the prone Yo-Yo IR1. "V" ̇E, "V" ̇O2 and "V" ̇CO2 were likely to very likely higher at 280 and 440 m (ES = 0.36-1.22), while peak values were possibly to likely higher (ES = 0.23-0.37) in the prone Yo-Yo IR1. Adopting a prone position during the Yo-Yo IR1 increases the internal, perceptual and external responses, placing greater emphasis on metabolically demanding actions typical of rugby.
    • Factors affecting the anthropometric and physical characteristics of elite academy rugby league players: a multi-club study.

      Dobbin, Nicholas; Moss, Samantha L.; Highton, Jamie M.; Twist, Craig; University of Chester (Human Kinetics, 2019-01-24)
      Purpose: To investigate the factors affecting the anthropometric and physical characteristics of elite academy rugby league players. Methods: One hundred and ninety-seven elite academy rugby league players (age = 17.3 ± 1.0 years) from five Super League clubs completed measures of anthropometric and physical characteristics during a competitive season. The interaction between, and influence of contextual factors on characteristics was assessed using linear mixed modelling. Results: Associations were observed between several anthropometric and physical characteristics. All physical characteristics improved during preseason and continued to improve until mid-season where thereafter 10 m sprint (η2 = 0.20 cf. 0.25), CMJ (η2 = 0.28 cf. 0.30) and prone Yo-Yo Intermittent Recovery Test (Yo-Yo IR) (η2 = 0.22 cf. 0.54) performance declined. Second (η2 = 0.17) and third (η2 = 0.16) years were heavier than first years, whilst third years had slower 10 m sprint times (η2 = 0.22). Large positional variability was observed for body mass, 20 m sprint time, medicine ball throw, countermovement jump, and prone Yo-Yo IR1. Compared to bottom-ranked teams, top demonstrated superior 20 m (η2 = -0.22) and prone Yo-Yo IR1 (η2 = 0.26) performance whilst middle-ranked teams reported higher CMJ height (η2 = 0.26) and prone Yo-Yo IR1 distance (η2 = 0.20), but slower 20 m sprint times (η2 = 0.20). Conclusion: These findings offer practitioners designing training programmes for academy rugby league players insight into the relationships between anthropometric and physical characteristics and how they are influenced by playing year, league ranking, position and season phase.
    • Glutamine supplementation reduces markers of intestinal permeability during running in the heat in a dose-dependent manner

      Pugh, Jamie; Sage, Stephen; Hutson, Mark; Doran, Dominic; Fleming, Simon; Highton, Jamie M.; Morton, James; Close, Graeme (Springer, 2017-10-20)
      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 ̇VO2max 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.
    • Influence of Knowledge of Task Endpoint on Pacing and Performance During Simulated Rugby League Match Play

      Mullen, Thomas; Twist, Craig; Highton, Jamie M.; University of Chester (Human Kinetics, 2017-10-31)
      Purpose: To examine the influence of knowledge of exercise duration on pacing and performance during simulated rugby league match play. Methods: Thirteen male university rugby players completed 3 simulated rugby league matches (RLMSP-i) on separate days in a random order. In a control trial, participants were informed that they would be performing 2 × 23-min bouts (separated by 20 min) of the RLMSP-i (CON). In a second trial, participants were informed that they would be performing 1 × 23-min bout of the protocol but were then asked to perform another 23-min bout (DEC). In a third trial, participants were not informed of the exercise duration and performed 2 × 23-min bouts (UN). Results: Distance covered and high-intensity running were higher in CON (4813 ± 167 m, 26 ± 4.1 m/min) than DEC (4764 ± 112 m, 25.2 ± 2.8 m/min) and UN (4744 ± 131 m, 24.4 m/min). Compared with CON, high-intensity running and peak speed were typically higher for DEC in bout 1 and lower in bout 2 of the RLMSP-i, while UN was generally lower throughout. Similarly, DEC resulted in an increased heart rate, blood lactate, and rating of perceived exertion than CON in bout 1, whereas these variables were lower throughout the protocol in UN. Conclusions: Pacing and performance during simulated rugby league match play depend on an accurate understanding of the exercise endpoint. Applied practitioners should consider informing players of their likely exercise duration to maximize running.
    • The internal and external responses to a forward-specific rugby league simulation protocol performed with and without physical contact

      Mullen, Thomas; Twist, Craig; Highton, Jamie M.; Dept Sport and Exercise Sciences, University of Chester (Human Kinetics Publishers, 2015-09-30)
      It is important to understand to what extent physical contact changes the internal and external load during rugby simulations that aim to replicate the demands of match play. Accordingly, this study examined the role of physical contact on the physiological and perceptual demands during and immediately after a simulated rugby league match. Nineteen male rugby players completed a ‘contact’ (CON) and a ‘non-contact’ (NCON) version of the rugby league match simulation protocol (RLMSP-i) in a randomized crossover design with one week between trials. Relative distance covered (ES = 1.27; ±0.29), low intensity activity (ES = 1.13; ±0.31), high-intensity running (ES = 0.49; ±0.34), heart rate (ES = 0.52; ±0.35), blood lactate concentration (ES = 0.78; ±0.34), RPE (ES = 0.72; ±0.38) and session RPE (ES = 1.45; ±0.51) were all higher in the CON compared to the NCON trial. However, peak speeds were lower in the CON trial (ES = -0.99; ±0.40) despite unclearreductions in knee extensor (ES = 0.19; ±0.40) and knee flexor (ES = 0.07; ±0.43) torque. Muscle soreness was also greater after CON compared to the NCON trial (ES = 0.97; ±0.55). The addition of physical contact to the movement demands of a simulated rugby league match increases many of the external and internal demands, but also results in players slowing their peak running speed during sprints. These findings highlight the importance of including contacts in simulation protocols and training practices designed to replicate the demands of real match play.
    • The movement and physiological demands of international and regional men's touch rugby matches

      Beaven, Robert; Highton, Jamie M.; Thorpe, Cari; Knott, Emma; Twist, Craig; University of Chester; Manchester Metropolitan University; Huddersfield University (Lippincott, Williams & Wilkins, 2014-05-14)
      This study compared the internal and external match demands imposed on international and regional standard male touch rugby players. The study adopted a cohort design with independent groups. Twelve international players (mean age 27.8 ± 6.2 y, body mass 72.8 ± 3.7 kg, stature 174.5 ± 5.4 cm) and nine regional players (mean age 25.5 ± 5.5 y, body mass 74.2 ± 7 kg, stature 174.1 ± 7 cm) were analysed during nine competitive matches from the 2013 season. Movement demands were measured using a 5 Hz global positioning system (GPS), alongside heart rate and session rating of perceived exertion (s-RPE) to quantify internal load. Total distance covered by international players was lower than regional players (2265.8 ± 562.3 cf. 2970 ± 558.9 m, p<0.05). However, international players had greater relative distance (137.1 ± 13.6 cf. 126.2 ± 17.2 m·min) due to shorter playing times per match (p<0.05). Absolute high speed running (>14 km·h) was not different between groups (p>0.05), but relative high speed running (39.3 ± 12.0 cf. 26.0 ± 13.6 m·min) was higher for international players. Regional players performed more absolute low speed activity (≤14 km·h) than international players (p<0.05), whereas relative low speed activity was not different between groups (p>0.05). Very high speed running (>20 km·h) distance, bout number and frequency, peak and average speed were all greater in international players (p<0.05). Higher average heart rate, summated heart rate and s-RPE (p<0.05) indicated higher internal loads during matches for regional players. These data indicate that performance in men's touch rugby is characterised by more relative high speed running and better repeated sprint capacities in higher standard players.
    • Movement demands of elite rugby league players during Australian National Rugby League and European Super League matches

      Twist, Craig; Highton, Jamie M.; Waldron, Mark; Edwards, Emma; Austin, Damien; Gabbett, Tim J.; University of Chester ; University of Chester ; University of New England, Australia ; University of Chester ; Sydney Swans Australian Football Club, Australia ; Australian Catholic University/University of Queensland (Human Kinetics Publishers, 2014-02-28)
      This study compared the movement demands of players competing in matches from the elite Australian and European rugby league competitions.
    • Pacing during a cross-country mountain bike mass-participation event according to race performance, experience, age and sex.

      Moss, Samantha L.; Francis, Ben; Calogiuri, Giovanna; Highton, Jamie M. (2018-12-15)
      This study describes pacing strategies adopted in an 86-km mass-participation cross-country marathon mountain bike race (the 'Birkebeinerrittet'). Absolute (km·h ) and relative speed (% average race speed) and speed coefficient of variation (%CV) in five race sections (15.1, 31.4, 52.3, 74.4 and 100% of total distance) were calculated for 8182 participants. Data were grouped and analysed according to race performance, age, sex and race experience. The highest average speed was observed in males (21.8 ± 3.7 km/h), 16-24 yr olds (23.0 ± 4.8 km/h) and those that had previously completed >4 Birkebeinerrittet races (22.5 ± 3.4 km/h). Independent of these factors, the fastest performers exhibited faster speeds across all race sections, whilst their relative speed was higher in early and late climbing sections (Cohen's d = 0.45-1.15) and slower in the final descending race section (d = 0.64-0.98). Similar trends were observed in the quicker age, sex and race experience groups, who tended to have a higher average speed in earlier race sections and a lower average speed during the final race section compared to slower groups. In all comparisons, faster groups also had a lower %CV for speed than slower groups (fastest %CV = 24.02%, slowest %CV = 32.03%), indicating a lower variation in speed across the race. Pacing in a cross-country mountain bike marathon is related to performance, age, sex and race experience. Better performance appears to be associated with higher relative speed during climbing sections, resulting in a more consistent overall race speed.
    • Passive heat maintenance after an initial warm-up improves high intensity activity during an interchange rugby league match simulation protocol.

      Fairbank, Matthew; Highton, Jamie M.; Twist, Craig; University of Chester (Lippincott, Williams & Wilkins, 2019-01-01)
      This study examined using passive heat maintenance to maintain core temperature after a warm-up and its effect on first half running performance in rugby players. Thirteen male rugby players completed this randomized crossover study. Tympanic temperature was taken before a warm-up and then after a further 15 minutes passive recovery either with (PHM) or without (CON) a passive heat maintenance garment. Participants then completed 23 min of the rugby league match simulation protocol (RLMSP-i). Differences in tympanic temperature were unclear between CON and PHM before (35.7 ± 1.3 cf. 36.0 ± 1.1oC; ES = 0.20) and during exercise (34.5 ± 0.1 cf. 35.2 ± 0.1oC; ES = 0.26-0.35). High-intensity running (ES = 0.27) and peak sprint speed were higher (ES = 0.46-0.56) during the PHM compared to the CON trial. Time spent above 20 W.kg-1 also increased in the first quartile of PHM compared to CON trial (ES = 0.18). All other between trial comparisons of performance were unclear. HRmean (ES = 0.38) was higher in PHM compared to CON, while differences in RPEmean (ES = -0.19) were unclear. There are small to large increases in high intensity work performed during a playing bout when rugby players wear a PHM garment after a warm-up. Rugby players should consider PHM during extended periods of time between a warm-up and starting a match.