• 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.
    • Changes in anthropometry and performance, and their inter-relationships, across three seasons in elite youth rugby league players

      Waldron, Mark; Worsfold, Paul R.; Twist, Craig; Lamb, Kevin L.; University of New England, Australia ; University of Chester ; University of Chester ; University of Chester (Lippincott, Williams & Wilkins, 2014-11-30)
      This study investigated changes in anthropometry and performance, and their inter-relationships, across three consecutive seasons (under-15 to under-17 age group) in elite youth rugby league players. Each player took part in annual anthropometrical and performance assessments, comprising measurements of stature; body mass; limb lengths and circumference; skinfolds, predicted muscle cross-sectional area (CSA); 20 m speed, counter-movement jump height, vertical power and aerobic power. Lean body mass % changed (P < 0.05) between the under-15 (70.9 ± 5.9 %), under-16 (72.0 ± 5.8 %) and the under-17 age groups (74.1 ± 5.7 %). Likewise, predicted quadriceps muscle cross-sectional area (CSA) also changed (P < 0.05) between each age group (under-15 = 120.9 ± 37.8 cm2; under-16 = 133.2 ± 36.0 cm2; under-17 = 154.8 ± 28.3 cm2). Concomitant changes between the under-15 and under-16 group were found for 20 m speed (3.5 ± 0.1 cf. 3.4 ± 0.2 s; P = 0.008) and predicted jumping power (3611.3 ± 327.3 W cf. 4081.5 ± 453.9 W; P = 0.003). Both lean body mass and quadriceps muscle CSA consistently, related to both 20 m sprint time and jumping power, with r-values ranging between -0.39 to –0.63 (20 m sprint time) and 0.55 to 0.75 (jumping power). Our findings demonstrate the importance of gains in lean body mass across later-adolescence that support the ability to generate horizontal speed and predicted vertical power. This information should inform the expectations and subsequent training programs of elite rugby league practitioners.
    • A longitudinal analysis of performance, growth and maturation in youth rugby league players: Implications for talent identification and development

      Worsfold, Paul R.; Twist, Craig; Lamb, Kevin L.; Waldron, Mark (University of Chester, 2013)
      This study monitored a cohort of youth rugby league players from one professional club in England, across three competitive seasons (under-15 to under-17 age group). The aims were to establish which dimensions of growth and performance characterized players who were either coach-selected or unselected each season and to evaluate annual developments in growth and performance. It was also necessary to establish the credibility of various measurement techniques that are implicated in the talent identification process. In the assessment of sprint performance, GPS measurements systematically underestimated both distance and timing gate speed but can be used to reliably evaluate sprint performance, particularly for measurements of peak speed (95% Limits of Agreement (LoA) = 0.00 ± 0.8 km·h-1; CV = 0.78%). Using a larger sample of youth team sport players (n = 60), multiple linear regression analysis, incorporating mean and peak GPS speeds as predictors of timing gate speed, yielded a prediction model that was able to provide a valid alternative to timing gates in the assessment of sprint performance over 30 m. With regards to the reliability of assessments of sport-specific skill in youth rugby league players, no comparisons met the pre-determined analytical goal of ‘perfect agreement’, meaning that up to 56% of players’ skill could be misinterpreted. The credibility of such assessments should be questioned and alternative tests considered. In the period between the under-15 and under-16 group, there were large annual increments in speed (5.02 Δ%), force (13.82 Δ%) and power (19.85 Δ%) generated over 10 m sprint intervals and predicted vertical jumping power (13.02 Δ%), with concomitant developments in body mass (5.14 Δ%), lean body mass (3.20 Δ%) and predicted muscle of the quadriceps (10.12 Δ%). A discriminant function analysis also highlighted 30 m force and 10 m acceleration as significant predictors of selected players in the under-15 group and under-16 group, explaining 47.3% and 40.7% of the between-group variance, respectively – which was the case independent of age at peak maturity. However, there were 5 no differences between selected and unselected players in the under-17 group. During match time, there were differences between selected (57.1 ± 11.9 min) and unselected (44.1 ± 12.3 min) players for average playing interval in the under-16 group. In turn, selected players covered more total distance (5181.0 ± 1063.5 m c.f. 3942.6 ± 1108.6 m, respectively; P = 0.012) and high intensity distance (1808.8 ± 369.3 m c.f. 1380.5 ± 367.7 m, respectively; P = 0.011) than unselected players. When age at peak height velocity (PHV) was statistically controlled, only distance in zone 3 and summated-HR remained higher in the selected players of the under-16 group. Conversely, higher values amongst the unselected under-16 players for total and relative distance in zone 4, 5 and high intensity were revealed. There was a relationship in the under-15 group (R = 0.702, P < 0.001), under-16 group (R = 0.607, P < 0.001) and under-17 group (R = 0.671, P < 0.006) between the number of successful ball carries and 10 m sprinting force, thus supporting the use of 10 m sprinting force as a predictor of match performance. The relationship (r = 0.51, P = 0.044) between aerobic capacity and HIT·min-1 in the under-17 group also provides preliminary evidence of aerobic endurance as a potential predictor of match running intensity. It was concluded that players who are coach-selected are not characterized by match related performance variables but are offered greater match exposure during the under-16 age group, resulting in larger running distances. Unselected players are unrewarded for higher intensity running during matches when maturational age is statistically controlled and are also equally effective in regard to tackling and ball carrying outcomes. These results collectively indicate the inability of match performance measurements to contribute to talent identification processes in players of this type. The changes in growth and performance should be used to guide talent development practices of rugby league coaches. In particular, the assessment of force (i.e. the product of acceleration and body mass) should be considered as an important factor in differentiating between higher and lower ability players, as well as relating to match performance.
    • 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.
    • The relationship between physical abilities, ball-carrying and tackling among elite youth rugby league players

      Waldron, Mark; Worsfold, Paul R.; Twist, Craig; Lamb, Kevin L.; University of Chester (Taylor & Francis, 2013-09-27)
      This study investigated the relationship between the physical abilities of adolescent rugby league players and tackling and ball-carrying skills performed during matches, across three seasons (under-15 to under-17). The players were measured each season for acceleration (10–30 m), peak and mean speed (10–30 m), sprinting force (10–30 m), aerobic power, counter-movement jump (CMJ) height and jumping power. The matches were filmed and analysed for ball-carrying and tackling frequency per minute (successful and unsuccessful outcomes). There were strong relationships between successful carries∙min–1 and 10 m force in the under-15 (R = 0.61, P < 0.001), under-16 (R = 0.69, P < 0.001) and under-17 groups (R = 0.64, P < 0.001). There were also strong and moderate relationships between predicted vertical power and successful carries∙min–1 in the under-15 (R = 0.63, P = 0.011) and under-17 group (R = 0.40, P = 0.030), respectively. There were no relationships between carries or tackles and any other performance indicators. These findings suggest that acceleration, in accordance with gains in body mass, support ball-carrying but not tackling performance. Performance measurements, such as CMJ or aerobic power, do not support ball-carrying ability among youth rugby league players.
    • The reliability of Functional Movement Screening (FMS) and in-season changes in physical function and performance among elite rugby league players

      Waldron, Mark; Gray, Adrian; Worsfold, Paul R.; Twist, Craig; University of New England, Australia ; University of New England, Australia ; University of Chester ; University of Chester (Lippincott, Williams & Wilkins, 2014-03-26)
      Functional Movement Screening (FMS) comprises seven tests that assess fundamental movement characteristics of athletes. However, the reliability of the FMS protocol and its sensitivity to changes in physical performance has not been appropriately investigated. Accordingly, this study aimed to assess the real-time reliability of the FMS protocol and to establish changes in both FMS and tests of physical performance throughout a season. The reliability of the FMS components (12 in total) were assessed via a non-parametric statistical approach, based on two trials, separated by one week. Score on the FMS, strength (3 RM full squat, 1 RM bench press), running speed (10 & 40 m) and jump height of 12 elite male under-19 rugby league players was monitored at pre-, mid- and late-season periods. There was no bias found between trials for the FMS, with the majority of components reaching 100% ‘perfect agreement’. There were no effects of season stage on any of the FMS components; however, an improvement in every performance test was apparent between the pre- and both mid- and late-season periods. Our findings demonstrate that the FMS can be reliably administered to elite rugby league players but question its sensitivity to systematic changes in athletic performance.
    • The reliability of tests for sport-specific skill amongst elite youth rugby league players

      Waldron, Mark; Worsfold, Paul R.; Twist, Craig; Lamb, Kevin L.; University of Chester (Taylor & Francis, 2012-08-10)
      In rugby league, tests of sport-specific skill often involve subjective assessments of performance by observers of varying qualification. However, the reliability of such subjective assessments has yet to be investigated via appropriate statistical techniques. Therefore, the aims of the current study were to investigate: (1) the intra-observer reliability of a non-qualified observer (‘novice’) and (2) the inter-observer reliability of the three observers (two qualified ‘experts’ and one novice observer) in the assessment of catching, passing and tackling (stages 1 and 2) ability in elite adolescent rugby league players (age: 14.790.5 years). Players performed each skill element within a simulated practice drill and were assessed in ‘real time’ by the observers according to pre-defined criteria. An overall bias (PB0.05) was revealed between the observers in stage 1 of catching and stage 1 of passing, the differences being higher for the novice compared to both expert coaches for each stage of catching and the first stage of passing, and between expert 2 and the novice for stage 2 of tackling. No comparisons met the pre-determined analytical goal of ‘perfect agreement’, for any of the skill components. Comparisons between the expert observers did not reach perfect agreement, with the lowest values occurring for both tackling skill stages (60 65%). None of the tests employed were sufficiently reliable to potentially discern between players of differing ability, which may mean up to 56% of players’ skill being misinterpreted. The credibility of such assessments should be questioned and alternative tests considered.
    • Swarming behaviour in elite race bunch cycling: a case study

      Waldron, Mark; Worsfold, Paul R.; White, Christopher; Murray, Stafford; University of Chester (Cardiff Metropolitan University, 2011-04)
      The current study undertook a dynamical systems analysis of race bunch cycling, considering the 'sports contest' as a dynamical, self organising system (McGarry et al., 2002). Data from one international track racing event was used to analyse a potential non-linear aggregation theory of 'swarming' in the 'points race', with two objectives; 1) To identify a race profile of a basic swarm mentality within the points race; 2) To identify system stability and the possible perturbation of stability in relation to successful and unsuccessful breakaways. Stability was based upon a 'normal' profile of race behaviours, measured by three separate dependent measures, namely; Absolute Difference, Rate of Change and Phase Duration. Results showed; 1) The points race exhibits the quintessential 'attract and repel' elements that characterise the swarm mentality 2) One-way ANOVA revealed that breakaways of both successful (3.3±1.2 half laps) and unsuccessful (3.1±1.5 half laps) conditions tend to differ from the race 'norm' (2.1±1.3 half laps) in terms of phase duration (F(2, 228)=18.4, P<0.05), suggesting that breakaways perturb the system through longer attract and repel phases. Results are discussed in relation to the current and future effectiveness of describing race bunch cycling as a dynamical system.
    • A three-season comparison of match performances among selected and unselected elite youth rugby league players

      Waldron, Mark; Worsfold, Paul R.; Twist, Craig; Lamb, Kevin L.; University of New England, Australia; University of Chester (Taylor & Francis, 2014-02-28)
      This study compared technical actions, movements, heart rates and perceptual responses of selected and unselected youth rugby league players during matches (under-15 to under-17). The players’ movements and heart rates were assessed using 5 Hz Global Positioning Systems (GPS), while their technical actions were analysed using video analysis. The maturity of each player was predicted before each season for statistical control. There were no differences (P > 0.05) between selected and unselected players in the under-15 or the under-17 age groups for any variables. However, in the under-16 group, the selected players (57.1 ± 11.9 min) played for longer than the unselected players (44.1 ± 12.3 min; P = 0.017; ES = 1.08 ± CI = 0.87), and covered more distance (5,181.0 ± 1063.5 m cf. 3942.6 ± 1,108.6m, respectively; P = 0.012; ES = 1.14 ± CI = 0.88) and high intensity distance (1,808.8 ± 369.3 m cf. 1,380.5 ± 367.7 m, respectively; P = 0.011; ES = 1.16 ± CI = 0.88). Although successful carries per minute was higher in the selected under-15 group, there were no other differences (P > 0.05) in match performance relative to playing minutes between groups. Controlling for maturity, the less mature, unselected players from the under-16 group performed more high-intensity running (P < 0.05). Our findings question the use of match- related measurements in differentiating between selected and unselected players, showing that later maturing players were unselected, even when performing greater high-intensity running during matches.
    • Transient fatigue is not influenced by ball-in-play time during elite rugby league matches

      Waldron, Mark; Highton, Jamie M.; Thomson, Edward; Twist, Craig; St Mary's University; University of New England; University of Chester (Lippincott, Williams & Wilkins, 2017-03-13)
      The capacity to sustain high-speed running is important for rugby league players. Transient fatigue, described as a reduction in high-speed running in the 5-min after a peak 5-min period, is a phenomenon observed during rugby league matches. This concept has recently been questioned based on the proposed confounding influence of ball-in-play time during these periods. Therefore, this study examined the changes in high-speed running (> 14 km∙h-1) of elite rugby league players, as well as ball-in-play time, during the peak, subsequent and mean 5-min periods of five competitive matches using 5 Hz GPS devices. The suitability of ball-in-play time as a covariate was also evaluated. The high-speed running and ball-in-play time was different between peak (26.7 ± 5.5 m∙min-1 and 177 ± 37 s) and subsequent (12.1 ± 6.2 m∙min-1 and 147 ± 37 s) 5-min periods (P < 0.05; most likely ↓). However, there was no relationship (r = 0.01 to -0.13; P > 0.05) between ball-in-play time and high-speed running and ball-in-play time was not independent of the match period. This study has reaffirmed the presence of transient fatigue during elite rugby league matches but questioned the influence of ball-in-play time as a confounding factor. These observations have implications for the design of appropriate training practices and informing tactical strategies employed by coaches. Most importantly, any practitioner wishing to measure transient fatigue could follow a similar statistical approach taken herein and, based on the current findings would not need to account for ball-in-play time as a confounding variable.