• 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.
    • Effects of a four-week touch rugby and self-paced interval running intervention on health markers in active young men.

      Dobbin, Nick; Bloyce, Daniel; Hughes, Stephen; Twist, Craig (Springer, 2020-03-29)
      Background: Modified team sport activity has been proposed as effective exercise modality for promoting markers of health that are comparable or greater than continuous forms of activity. However, research using modified team sports is currently limited to sedentary populations using 2-3 sessions across a minimum of 8 weeks. Aim: To investigate the effects of a four-week touch rugby and self-paced interval running intervention on a range of health markers in active men. Methods: Sixteen participants (age 26.4 ± 6.4 years) were matched for age, demographic and physical activity before completing a single touch rugby (n = 8) or running (n = 8) session per week for four weeks. Measures of systolic and diastolic blood pressure, resting heart rate (RHR), body composition and biochemical status were recorded pre- and post-intervention. Results: ANCOVA analysis revealed between-group differences for impedance (P = 0.027), fat mass (P = 0.008), percentage body fat (P = 0.008) and fat free mass (P = 0.002), with greater changes after touch rugby. Systolic blood pressure decreased for both groups with greater reductions observed after touch rugby (P = 0.002). No between-group difference was observed for RHR, interleukin-6 or C-reactive protein (P > 0.05). Contrasting internal, external and perceptual loads were observed. Conclusion: The results of this study suggest that a single session of touch rugby over a 4-week period elicited greater improvements in body composition and SBP that self-paced running, with both equally beneficial for improving RHR, diastolic blood pressure and improved inflammatory status in active young men.
    • 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.
    • Physiological and anthropometric determinants of critical power, W′ and the reconstitution of W′ in trained and untrained male cyclists

      Chorley, Alan; Bott, Richard P; Marwood, Simon; Lamb, Kevin L; University of Chester (Springer, 2020-08-09)
      Abstract Purpose This study examined the relationship of physiological and anthropometric characteristics with parameters of the critical power (CP) model, and in particular the reconstitution of W′ following successive bouts of maximal exercise, amongst trained and untrained cyclists. Methods Twenty male adults (trained nine; untrained 11; age 39 ± 15 year; mass 74.7 ± 8.7 kg; V̇O2max 58.0 ± 8.7 mL kg−1 min−1) completed three incremental ramps (20 W min−1) to exhaustion interspersed with 2-min recoveries. Pearson’s correlation coefficients were used to assess relationships for W′ reconstitution after the first recovery (W′rec1), the delta in W′ reconstituted between recoveries (ΔW′rec), CP and W′. Results CP was strongly related to V̇O2max for both trained (r = 0.82) and untrained participants (r = 0.71), whereas W′ was related to V̇O2max when both groups were considered together (r = 0.54). W′rec1 was strongly related to V̇O2max for the trained (r = 0.81) but not untrained (r = 0.18); similarly, ΔW′rec was strongly related to V̇O2max (r = − 0.85) and CP (r = − 0.71) in the trained group only. Conclusions Notable physiological relationships between parameters of aerobic fitness and the measurements of W′ reconstitution were observed, which differed among groups. The amount of W′ reconstitution and the maintenance of W′ reconstitution that occurred with repeated bouts of maximal exercise were found to be related to key measures of aerobic fitness such as CP and V̇O2max. This data demonstrates that trained cyclists wishing to improve their rate of W′ reconstitution following repeated efforts should focus training on improving key aspects of aerobic fitness such as V̇O2max and CP.
    • Physiological characteristics of female soccer players and health and performance considerations: A narrative review

      Randell, Rebecca; Clifford, Thomas; Drust, Barry; Moss, Samantha; Unnithan, Viswanath; De Ste Croix, Mark; Datson, Naomi; Martin, Daniel; Mayho, Hannah; Carter, James; et al.
      Female soccer has seen a substantial rise in participation, as well as increased financial support from governing bodies over the last decade. Thus, there is an onus on researchers and medical departments to develop a better understanding of the physical characteristics and demands, and the health and performance needs of female soccer players. In this review we discuss the current research, as well as the knowledge gaps, of six major topics: physical demands, talent identification, body composition, injury risk and prevention, health, and nutrition. Data on female talent identification are scarce, and future studies need to elucidate the influence of relative age and maturation selection across age groups. Regarding the physical demands, more research is needed on the pattern of high-intensity sprinting during matches and the contribution of soccer-specific movements. Injuries are not uncommon in female soccer players, but targeting intrinsically modifiable factors with injury prevention programmes can reduce injury rates. The anthropometric and physical characteristics of female players are heterogenous and setting specific targets should be discouraged in youth and sub-elite players. Menstrual cycle phase may influence performance and injury risk; however, there are few studies in soccer players. Nutrition plays a critical role for health and performance and ensuring adequate energy intake remains a priority. Despite recent progress, there is considerably less research in female than male soccer players. Many gaps in our understanding of how best to develop and manage the health and performance of female soccer players remain.