Browsing Sport and Exercise Sciences by Authors
No Effect of Beetroot Juice Supplementation on 100-m and 200-m Swimming Performance in Moderately-Trained Swimmers.Esen, Ozcan; Nicholas, Ceri; Morris, Mike; Bailey, Stephen J (2018-11-14)Dietary nitrate supplementation has been reported to improve performance in kayaking and rowing exercise which mandate significant recruitment of the upper body musculature. Since the effect of dietary nitrate supplementation on swimming performance is unclear, the purpose of this study was to assess the effect of dietary nitrate supplementation on 100-m and 200-m swimming freestyle time-trial (TT) performance. In a double blind, randomized crossover design, ten moderately-trained swimmers underwent two separate 3-day supplementation periods, with a daily dose of either 140 mL nitrate-rich (BRJ; ~800 mg/d nitrate) or nitrate-depleted (PLA) BRJ. Following blood sampling on day 3, the swimmers performed both 200-m and 100-m freestyle swimming TTs, with 30 min recovery between trials. Plasma nitrite concentrations was greater after BRJ relative to PLA consumption (432 ± 203 nmol/L, 111 ± 56 nmol/L, respectively, p = 0.001). Systolic BP was lowered after BRJ compared to PLA supplementation (114 ± 10, 120 ± 10 mmHg, respectively p = 0.001), but time to complete the 200-m (BRJ: 152.6 ± 14.1 s, PLA: 152.5 ± 14.1 s) and 100-m (BRJ: 69.5 ± 7.2 s, PLA: 69.4 ± 7.4 s) freestyle swimming TTs were not different between BRJ and PLA (p > 0.05). While 3 days of BRJ supplementation increased plasma nitrite concentration and lowered blood pressure, it did not improve 100-m and 200-m swimming TT performance. These results do not support an ergogenic effect of nitrate supplementation in moderately-trained swimmers, at least for 100-m and 200-m freestyle swimming performance.
Predicting maximal oxygen uptake via a perceptually regulated exercise test (PRET)Morris, Mike; Lamb, Kevin L.; Cotterrell, David; Buckley, John P.; University of Chester (2009-12-08)Recent research has yielded encouraging, yet inconsistent findings concerning the validity and reliability of predicting maximal oxygen uptake (O2 max) from a graded perceptually regulated exercise test (PRET). Accordingly, the purpose of the present study was to revisit the validity and reliability of this application of ratings of perceived exertion (RPE) using a modified PRET protocol. Twenty-three volunteers (mean age, 31 ± 9.9 years) completed four counter-balanced PRETs (involving two 2-minute and two 3-minute bouts administered over 9 days, each separated by 48 hours) on an electromagnetically braked cycle ergometer and one maximal graded exercise test. Participants self-regulated their exercise at RPE levels 9, 11, 13, 15 and 17 in a randomized order. Oxygen uptake (O2) was recorded continuously during each bout. The O2 values for the RPE ranges 9-17, 9-15 and 9-13 were extrapolated to RPE 20 using regression analysis to predict individual O2 max scores.
The validity and reliability of predicting maximal oxygen uptake from a treadmill-based sub-maximal perceptually regulated exercise testMorris, 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.