• 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.
    • The effects of exercise-induced muscle damage on maximal intensity intermittent exercise performance

      Twist, Craig; Eston, Roger; University College Chester ; University of Exeter (Spring-Verlag, 2009-05-18)
      Exercise-induced muscle damage (EIMD) is a common occurrence following activities with a high eccentric component. Alterations to the torque-velocity relationship following EIMD would appear to have serious implications for athletic performance, particularly as they relate to impairment of maximal intensity exercise. However, this has been studied infrequently. The purpose of this study was to assess the effects of EIMD on maximal intermittent sprint performance. Ten male participants (age 22.4±3.2 years, height 178.6±5.2 cm, mass 80.6±10.7 kg) performed 10×6 s cycle ergometer sprints, interspersed with 24 s recovery against a load corresponding to 0.10 kp/kg and 10×10 m sprints from a standing start, each with 12 s active (walking) recovery. All variables were measured immediately before and at 30 min, 24, 48 and 72 h following a plyometric exercise protocol comprising of 10×10 maximal counter movement jumps. Repeated measures ANOVA showed significant changes over time (all P<0.05) for perceived soreness, plasma creatine kinase activity (CK), peak power output (PPO), sprint time and rate of fatigue. Soreness was significantly higher (P<0.01) than baseline values at all time intervals (3.1, 4.9, 5.5 and 3.2 at 30 min, 24, 48 and 72 h, respectively). CK was significantly elevated (P<0.05) at 24 h (239 IU/l) and 48 h (245 IU/l) compared to baseline (151 IU/l). PPO was significantly lower (P<0.05) than baseline (1,054 W) at all time intervals (888, 946, 852 and 895 W, at 30 min, 24, 48 and 72 h, respectively). The rate of fatigue over the ten cycling sprints was reduced compared to baseline, with the greatest reduction of 48% occurring at 48 h (P<0.01). This was largely attributed to the lower PPO in the initial repetitions, resulting in a lower starting point for the rate of fatigue. Values returned to normal at 72 h. Sprint times over 10 m were higher (P<0.05) at 30 min, 24 h and 48 h compared to baseline (1.96 s) with values corresponding to 2.01, 2.02 and 2.01 at 30 min, 24 h and 48 h, respectively. Values returned to baseline by 72 h. The results provide further evidence that, following a plyometric, muscle-damaging exercise protocol, the ability of the muscle to generate power is reduced for at least 3 days. This is also manifested by a small, but statistically significant reduction in very short-term (?2 s) intermittent sprint running performance. These findings have implications for appropriate training strategies in multiple sprint sports.
    • 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.
    • Lower-volume muscle-damaging exercise protects against high-volume muscle-damaging exercise and the detrimental effects on endurance performance

      Burt, Dean G.; Lamb, Kevin L.; Nicholas, Ceri; Twist, Craig; University of Chester; Staffordshire University (Springer Verlag, 2015-02-21)
      Purpose: This study examined whether lower-volume exercise-induced muscle damage (EIMD) performed 2 weeks before high-volume muscle-damaging exercise protects against its detrimental effect on running performance. Methods: Sixteen male participants were randomly assigned to a lower-volume (five sets of ten squats, n = 8) or high-volume (ten sets of ten squats, n = 8) EIMD group and completed baseline measurements for muscle soreness, knee extensor torque, creatine kinase (CK), a 5-min fixedintensity running bout and a 3-km running time-trial. Measurements were repeated 24 and 48 h after EIMD, and the running time-trial after 48 h. Two weeks later, both groups repeated the baseline measurements, ten sets of ten squats and the same follow-up testing (Bout 2). Results: Data analysis revealed increases in muscle soreness and CK and decreases in knee extensor torque 24–48 h after the initial bouts of EIMD. Increases in oxygen uptake ˙V O2 , minute ventilation ˙V E and rating of perceived exertion were observed during fixed-intensity running 24–48 h after EIMD Bout 1. Likewise, time increased and speed and ˙V O2 decreased during a 3-km running time-trial 48 h after EIMD. Symptoms of EIMD, responses during fixed-intensity and running time-trial were attenuated in the days after the repeated bout of high-volume EIMD performed 2 weeks after the initial bout. Conclusions: This study demonstrates that the protective effect of lower-volume EIMD on subsequent high-volume EIMD is transferable to endurance running. Furthermore, time-trial performance was found to be preserved after a repeated bout of EIMD.
    • 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.
    • The validity and reliability of predicting maximal oxygen uptake from a treadmill-based sub-maximal perceptually regulated exercise test

      Morris, Mike; Lamb, Kevin L.; Hayton, John; Cotterrell, David; Buckley, John P.; University of Chester ; (Springer-Verlag, 2010-03-30)
      The purpose of this study was to determine for the first time whether VO2max could be predicted accurately and reliably from a treadmill-based perceptually regulated exercise test (PRET) incorporating a safer and more practical upper limit of RPE 15 ("Hard") than used in previous investigations.
    • The validity of predicting maximal oxygen uptake from a perceptually-regulated graded exercise test

      Eston, Roger; Lamb, Kevin L.; Parfitt, Gaynor; King, Nicholas; University of Exeter ; University of Chester ; University of Exeter ; University of Wales, Bangor (Springer-Verlag, 2005-04-07)
      The purpose of this study was to assess the validity of predicting maximal oxygen uptake from sub-maximal values elicited during a perceptually-regulated exercise test. We hypothesised that the strong relationship between the ratings of perceived exertion (RPE) and would enable to be predicted and that this would improve with practice. Ten male volunteers performed a graded exercise test (GXT) to establish followed by three sub-maximal RPE production protocols on a cycle ergometer, each separated by a period of 48 h.