No Improvement of Repeated-Sprint Performance With Dietary Nitrate

2014 ◽  
Vol 9 (5) ◽  
pp. 845-850 ◽  
Author(s):  
Kristy Martin ◽  
Disa Smee ◽  
Kevin G. Thompson ◽  
Ben Rattray
Keyword(s):  
Power Output ◽  
High Intensity ◽  
Cycle Ergometer ◽  
Sprint Performance ◽  
Mean Power ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Repeated Sprint ◽  
Nitrate Supplementation ◽  
Mean Power Output

Purpose:Nitrate supplementation improves endurance exercise and single bouts of high-intensity activity, but its effect on repeated sprints is unclear. This study is the first to investigate the effects of acute dietary nitrate supplementation during a high-intensity intermittent-sprint test to exhaustion.Methods:Team-sport athletes (9 male, age 22.3 ± 2.1 y, VO2max 57.4 ± 8.5 mL · kg−1 · min−1; 7 female, age 20.7 ± 1.3 y, VO2max 47.2 ± 8.5 mL · kg−1 · min−1) were assigned to a double-blind, randomized, crossover design. Participants consumed 70 mL of concentrated beetroot juice containing a minimum of 0.3 g of nitrate (NT) or 70 mL of placebo (PL) 2 h before a repeated-sprint protocol involving repeated 8-s sprints with 30-s recovery on a cycle ergometer to exhaustion.Results:Fewer sprints (NT = 13 ± 5 vs PL = 15 ± 6, P = .005, d = 0.41) and less total work (NT = 49.2 ± 24.2 kJ vs PL = 57.8 ± 34.0 kJ, P = .027, d = 0.3) were completed in NT relative to PL. However there was no difference in overall mean power output or the mean power output for each individual 8-s sprint.Conclusions:These findings suggest that dietary nitrate is not beneficial for improving repeated-sprint performance, at least when such sprints are near-maximal and frequent in nature. The lack of an effect of nitrate at near-maximal oxygen uptake supports the suggestion that at greater exercise intensities nitrate does not have an ergogenic effect.

scholarly journals The Effect of Beetroot Ingestion on High-Intensity Interval Training: A Systematic Review and Meta-Analysis

Nutrients ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 3674
Author(s):  
Tak Hiong Wong ◽  
Alexiaa Sim ◽  
Stephen F. Burns
Keyword(s):  
Systematic Review ◽  
Power Output ◽  
High Intensity ◽  
Meta Analysis ◽  
Interval Training ◽  
High Intensity Interval Training ◽  
Mean Power ◽  
Nitrate Supplementation ◽  
High Intensity Interval ◽  
Mean Power Output

Dietary nitrate supplementation has shown promising ergogenic effects on endurance exercise. However, at present there is no systematic analysis evaluating the effects of acute or chronic nitrate supplementation on performance measures during high-intensity interval training (HIIT) and sprint interval training (SIT). The main aim of this systematic review and meta-analysis was to evaluate the evidence for supplementation of dietary beetroot—a common source of nitrate—to improve peak and mean power output during HIIT and SIT. A systematic literature search was carried out following PRISMA guidelines and the PICOS framework within the following databases: PubMed, ProQuest, ScienceDirect, and SPORTDiscus. Search terms used were: ((nitrate OR nitrite OR beetroot) AND (HIIT or high intensity or sprint interval or SIT) AND (performance)). A total of 17 studies were included and reviewed independently. Seven studies applied an acute supplementation strategy and ten studies applied chronic supplementation. The standardised mean difference for mean power output showed an overall trivial, non-significant effect in favour of placebo (Hedges’ g = −0.05, 95% CI −0.32 to 0.21, Z = 0.39, p = 0.69). The standardised mean difference for peak power output showed a trivial, non-significant effect in favour of the beetroot juice intervention (Hedges’ g = 0.08, 95% CI -0.14 to 0.30, Z = 0.72, p = 0.47). The present meta-analysis showed trivial statistical heterogeneity in power output, but the variation in the exercise protocols, nitrate dosage, type of beetroot products, supplementation strategy, and duration among studies restricted a firm conclusion of the effect of beetroot supplementation on HIIT performance. Our findings suggest that beetroot supplementation offers no significant improvement to peak or mean power output during HIIT or SIT. Future research could further examine the ergogenic potential by optimising the beetroot supplementation strategy in terms of dosage, timing, and type of beetroot product. The potential combined effect of other ingredients in the beetroot products should not be undermined. Finally, a chronic supplementation protocol with a higher beetroot dosage (>12.9 mmol/day for 6 days) is recommended for future HIIT and SIT study.

scholarly journals Effects of Acute Hypoxia on Lactate Thresholds and High-Intensity Endurance Performance—A Pilot Study

2021 ◽  
Vol 18 (14) ◽  
pp. 7573
Author(s):  
Martin Faulhaber ◽  
Katharina Gröbner ◽  
Linda Rausch ◽  
Hannes Gatterer ◽  
Verena Menz
Keyword(s):  
Power Output ◽  
High Intensity ◽  
Acute Hypoxia ◽  
Endurance Performance ◽  
Cycle Ergometer ◽  
Normobaric Hypoxia ◽  
Simulated Altitude ◽  
Mean Power ◽  
Mean Power Output ◽  
Induced Changes

The present project compared acute hypoxia-induced changes in lactate thresholds (methods according to Mader, Dickhuth and Cheng) with changes in high-intensity endurance performance. Six healthy and well-trained volunteers conducted graded cycle ergometer tests in normoxia and in acute normobaric hypoxia (simulated altitude 3000 m) to determine power output at three lactate thresholds (PMader, PDickhuth, PCheng). Subsequently, participants performed two maximal 30-min cycling time trials in normoxia (test 1 for habituation) and one in normobaric hypoxia to determine mean power output (Pmean). PMader, PDickhuth and PCheng decreased significantly from normoxia to hypoxia by 18.9 ± 9.6%, 18.4 ± 7.3%, and 11.5 ± 6.0%, whereas Pmean decreased by only 8.3 ± 1.6%. Correlation analyses revealed strong and significant correlations between Pmean and PMader (r = 0.935), PDickhuth (r = 0.931) and PCheng (r = 0.977) in normoxia and partly weaker significant correlations between Pmean and PMader (r = 0.941), PDickhuth (r = 0.869) and PCheng (r = 0.887) in hypoxia. PMader and PCheng did not significantly differ from Pmean (p = 0.867 and p = 0.784) in normoxia, whereas this was only the case for PCheng (p = 0.284) in hypoxia. Although investigated in a small and select sample, the results suggest a cautious application of lactate thresholds for exercise intensity prescription in hypoxia.

scholarly journals Re-esterified DHA improves ventilatory threshold 2 in competitive amateur cyclists

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Vicente Ávila-Gandía ◽  
Antonio Torregrosa-García ◽  
Antonio J. Luque-Rubia ◽  
María Salud Abellán-Ruiz ◽  
Desirée Victoria-Montesinos ◽  
...  
Keyword(s):  
Power Output ◽  
Ventilatory Threshold ◽  
Heart Rate Recovery ◽  
Recovery Phase ◽  
Lactate Clearance ◽  
Mean Power ◽  
Double Blind ◽  
Cycling Test ◽  
Competitive Cyclists ◽  
Mean Power Output

Abstract Background Fish oils were studied as ergogenic aids in a number of mixed physical trial designs showing promising results. However, the heterogeneous purity of the studied supplements, combined with the variety of physical tests employed call for more studies to confirm these findings, ideally with standardised supplements. Our aim was to test a supplement highly concentrated in DHA (DHA:EPA ratio equal to approximately 8:1) on a maximal cycling test to elucidate performance improvements mainly due to DHA. Methods A double-blind, placebo controlled, randomised balanced, parallel design, in competitive amateur cyclists was employed. They were all male, older than 18 years old, with training routine of 2 to 4 sessions per week lasting at least one hour each. A ramp cycling test to exhaustion with a subsequent 5 min recovery phase was employed before and after treatment to analyse aerobic metabolism and lactate clearance after the bout. After 30 days of supplementation with 975 mg of re-esterified DHA, the thirty-eight cyclist who completed the study were finally included for statistical analysis. Results Mean power output at ventilatory threshold 2 (VT2) improved after DHA supplementation both as absolute (△DHA versus △PLA: 6.33–26.54 Watts; CI 95%) and relative (p=0.006) values, paralleled with higher oxygen consumption at VT2 both for absolute (DHA 2729.4 ±304.5, 3045.9 ±335.0; PLA 2792.3 ±339.5, 2845.5 ±357.1; ml·min−1 baseline versus post p=0.025) and relative values (DHA 36.6 ±5.0, 41.2 ±5.4; PLA 37.2 ±5.7, 38.1 ±5.2; ml·kg−1·min−1 baseline versus post p=0.024). Heart rate recovery rate improved during the recovery phase in the DHA group compared to PLA (p=0.005). Conclusion DHA is capable of improving mean power output at the ventilatory threshold 2 (anaerobic ventilatory threshold) in amateur competitive cyclists. It is unclear if these findings are the result of the specific DHA supplement blend or another factor.

Failure of Glycine-Arginine-α-Ketoisocaproic Acid to Improve High-Intensity Exercise Performance in Trained Cyclists

2011 ◽  
Vol 21 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Lukas Beis ◽  
Yaser Mohammad ◽  
Chris Easton ◽  
Yannis P. Pitsiladis
Keyword(s):  
Exercise Performance ◽  
High Intensity ◽  
Perceived Exertion ◽  
Cycle Ergometer ◽  
High Intensity Exercise ◽  
Ratings Of Perceived Exertion ◽  
Mean Power ◽  
Double Blind ◽  
Oral Supplementation ◽  
Experimental Trials

Oral supplementation with glycine-arginine-α-ketoisocaproic acid (GAKIC) has previously been shown to improve exhaustive high-intensity exercise performance. There are no controlled studies involving GAKIC supplementation in well-trained subjects. The aim of the current study was to examine the effects of GAKIC supplementation on fatigue during high-intensity, repeated cycle sprints in trained cyclists. After at least 2 familiarization trials, 10 well-trained male cyclists completed 2 supramaximal sprint tests each involving 10 sprints of 10 s separated by 50-s rest intervals on an electrically braked cycle ergometer. Subjects ingested 11.2 g of GAKIC or placebo (Pl) during a period of 45 min before the 2 experimental trials, administered in a randomized and double-blind fashion. Peak power declined from the 1st sprint (M ± SD; Pl 1,332 ± 307 W, GAKIC 1,367 ± 342 W) to the 10th sprint (Pl 1,091 ± 229 W, GAKIC 1,061 ± 272 W) and did not differ between conditions (p = .88). Mean power declined from the 1st sprint (Pl 892 ± 151 W, GAKIC 892 ± 153 W) to the 10th sprint (Pl 766 ± 120 W, GAKIC 752 ± 138 W) and did not differ between conditions (p = .96). The fatigue index remained at ~38% throughout the series of sprints and did not differ between conditions (p = .99). Heart rate and ratings of perceived exertion increased from the 1st sprint to the 10th sprint and did not differ between conditions (p = .11 and p = .83, respectively). In contrast to previous studies in untrained individuals, these results suggest that GAKIC has no ergogenic effect on repeated bouts of high-intensity exercise in trained individuals.

Effects of Carbohydrate Ingestion and Carbohydrate Mouth Rinse on Repeat Sprint Performance

2017 ◽  
Vol 27 (3) ◽  
pp. 204-212 ◽  
Author(s):  
Ben M. Krings ◽  
Timothy J. Peterson ◽  
Brandon D. Shepherd ◽  
Matthew J. McAllister ◽  
JohnEric W. Smith
Keyword(s):  
Heart Rate ◽  
Power Output ◽  
Sprint Performance ◽  
Rating Of Perceived Exertion ◽  
Mouth Rinse ◽  
Total Work ◽  
Fatigue Index ◽  
Mean Power ◽  
Carbohydrate Ingestion ◽  
Mean Power Output

The purpose of this investigation was to examine to the influence of carbohydrate ingestion (CHOI) and carbohydrate mouth rinse (CHOR) on acute repeat maximal sprint performance. Fourteen healthy males (age: 21.7 ± 1.8 years, mass: 82.3 ± 12.3 kg) completed a total of five 15-s maximal repeat sprints on a cycle ergometer against 0.075 kg ・ kg-1 body mass each separated by 4 min of active recovery. Subjects completed four experimental trials and were randomly assigned one of four treatments: (1) CHOI, (2) CHOR, (3) placebo mouth rinse (PLAR), (4) placebo ingestion (PLAI). Subjects rinsed or ingested six 50 mL 10% CHO solutions throughout each trial. Performance variables measured included rating of perceived exertion, peak heart rate, peak and mean power output, fatigue index, and total work. Significant treatment main effects were observed for mean power output (p = 0.026), total work (p = 0.020), fatigue index (p = 0.004), and heart rate (p = 0.013). Overall mean power output and total work were significantly greater with CHOI (659.3 ± 103.0 watts, 9849.8 ± 1598.8 joules) compared with CHOR (645.8 ± 99.7 watts, 9447.5 ± 1684.9 joules, p < .05). CHOI (15.3 ± 8.6 watts/s) significantly attenuated fatigue index compared with CHOR (17.7 ± 10.4 watts/s, p < .05). Based on our findings, CHOI was more likely to provide a beneficial performance effect compared with CHOR, PLAI, and PLAR. Athletes required to complete repeat bouts of high intensity exercise may benefit from CHOI.

N-acetylcysteine alters substrate metabolism during high-intensity cycle exercise in well-trained humans

2013 ◽  
Vol 38 (12) ◽  
pp. 1217-1227 ◽  
Author(s):  
Adam J. Trewin ◽  
Aaron C. Petersen ◽  
Francois Billaut ◽  
Leon R. McQuade ◽  
Bernie V. McInerney ◽  
...  
Keyword(s):  
Power Output ◽  
High Intensity ◽  
Repeated Measures ◽  
Vastus Lateralis ◽  
Venous Blood ◽  
Time Trial ◽  
Peak Power Output ◽  
Mean Power ◽  
Double Blind ◽  
Substrate Metabolism

We investigated the effects of N-acetylcysteine (NAC) on metabolism during fixed work rate high-intensity interval exercise (HIIE) and self-paced 10-min time-trial (TT10) performance. Nine well-trained male cyclists (V̇O2peak, 69.4 ± 5.8 mL·kg−1·min−1; peak power output (PPO), 385 ± 43 W; mean ± SD) participated in a double-blind, repeated-measures, randomised crossover trial. Two trials (NAC supplementation and placebo) were performed 7 days apart consisting of 6 × 5 min HIIE bouts at 82% PPO (316 ± 40 W) separated by 1 min at 100 W, and then after 2 min of recovery at 100 W, TT10 was performed. Expired gases, venous blood, and electromyographic (EMG) data were collected. NAC did not influence blood glutathione but decreased lipid peroxidation compared with the placebo (P < 0.05). Fat oxidation was elevated with NAC compared with the placebo during HIIE bouts 5 and 6 (9.9 ± 8.9 vs. 3.9 ± 4.8 μmol·kg−1·min−1; P < 0.05), as was blood glucose throughout HIIE (4.3 ± 0.6 vs. 3.8 ± 0.6 mmol·L−1; P < 0.05). Blood lactate was lower with NAC after TT10 (3.3 ± 1.3 vs. 4.2 ± 1.3 mmol·L−1; P < 0.05). Median EMG frequency of the vastus lateralis was lower with NAC during HIIE (79 ± 10 vs. 85 ± 10 Hz; P < 0.05), but not TT10 (82 ± 11 Hz). Finally, NAC decreased mean power output 4.9% ± 6.6% (effect size = –0.3 ± 0.4, mean ± 90% CI) during TT10 (305 ± 57 W vs. 319 ± 45 W). These data suggest that NAC alters substrate metabolism and muscle fibre type recruitment during HIIE, which is detrimental to time-trial performance.

scholarly journals Warm-up durations in a hot-dry climate affect thermoregulation, mean power-output and fatigue, but not peak power in specific soccer repeated-sprint ability

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Mohamed Frikha ◽  
Nesrine Chaâri ◽  
Noureddine Ben Said ◽  
Mohammed Shaab Alibrahim
Keyword(s):  
Power Output ◽  
Peak Power ◽  
Perceived Exertion ◽  
Rating Of Perceived Exertion ◽  
Tympanic Temperature ◽  
Muscular Power ◽  
Mean Power ◽  
Warm Up ◽  
Repeated Sprint ◽  
Mean Power Output

Abstract Background This study addressed the lack of data on the effect of warm-up (WU) duration in hot-dry climate (~ 30 °C; ~ 18% RH), on thermoregulation, muscular power-output, and fatigue after specific soccer repeated-sprint test (RSA). Methods Eleven amateur soccer players participated in a cross-over randomized study and they underwent the Bangsbo repeated-sprint test, after three WU durations (i.e. WU10, WU15 and WU20 min) at 70% of MAV, and on different days. Peak power (PP), mean power (MP) and the fatigue index (FI) were recorded and analyzed. Likewise, heart rate (HR), tympanic temperature (Ttym), mean body temperature (MBT) and rating of perceived exertion (RPE) were recorded during each session. Results The repeated measure ANOVA showed that MP improved after WU15 in comparison to WU10 and WU20 (p = 0.04 and p = 0.001; respectively). Nonetheless, no significant effect on PP was recorded after all WU durations. FI during RSA increased after WU20 in comparison to WU15 and WU10 (p < 0.001 and p = 0.003; respectively). Higher RPE values (p < 0.001) were recorded after WU15 and WU20 in comparison to WU10 duration. The two-way ANOVA showed higher ΔTtym and ΔMBT values after WU15 and WU20 compared to WU10 (p = 0.039 and p < 0.001for Ttym; p = 0.005 and p < 0.001 for MBT, respectively). Conclusions The WU15 at 70% of MAV better assists mean power-output during soccer RSA in hot-dry (~ 30 °C; 18% RH) climate, but not peak power. Reducing WU duration up to 10 min seems to be insufficient to induce beneficial physiological changes necessary for optimizing repeated-sprint performance, while its extension up to 20 min remains detrimental for muscular power and induces higher fatigue.

Acute Beetroot Juice Supplementation Does Not Improve Cycling Performance in Normoxia or Moderate Hypoxia

2015 ◽  
Vol 25 (4) ◽  
pp. 359-366 ◽  
Author(s):  
Kristin E. MacLeod ◽  
Sean F. Nugent ◽  
Susan I. Barr ◽  
Michael S. Koehle ◽  
Benjamin C. Sporer ◽  
...  
Keyword(s):  
Steady State ◽  
Power Output ◽  
Time Trial ◽  
Small Sample ◽  
Oxygen Cost ◽  
Beetroot Juice ◽  
Mean Power ◽  
Double Blind ◽  
Moderate Hypoxia ◽  
Mean Power Output

Beetroot juice (BR) has been shown to lower the oxygen cost of exercise in normoxia and may have similar effects in hypoxia. We investigated the effect of BR on steady-state exercise economy and 10-km time trial (TT) performance in normoxia and moderate hypoxia (simulated altitude: ~2500 m). Eleven trained male cyclists (VO2peak ≥ 60 ml·kg-1·min-1) completed four exercise trials. Two hours before exercise, subjects consumed 70 mL BR (~6 mmol nitrate) or placebo (nitrate-depleted BR) in a randomized, double-blind manner. Subjects then completed a 15-min self-selected cycling warm-up, a 15-min steady-state exercise bout at 50% maximum power output, and a 10-km time trial (TT) in either normoxia or hypoxia. Environmental conditions were randomized and single-blind. BR supplementation increased plasma nitrate concentration and fraction of exhaled nitric oxide relative to PL (p < .05 for both comparisons). Economy at 50% power output was similar in hypoxic and normoxic conditions (p > .05), but mean power output was greater in the normoxic TT relative to the hypoxic TT (p < .05). BR did not affect economy, steady-state SpO2, mean power output, or 10-km TT completion time relative to placebo in either normoxia or hypoxia (p > .05 in all comparisons). In conclusion, BR did not lower the oxygen cost of steady-state exercise or improve exercise performance in normoxia or hypoxia in a small sample of well-trained male cyclists.

The Effect of Whole-Body Vibration on Subsequent Sprint Performance in Well-Trained Cyclists

2017 ◽  
Vol 12 (7) ◽  
pp. 964-968 ◽  
Author(s):  
Bent R. Rønnestad ◽  
Gunnar Slettaløkken Falch ◽  
Stian Ellefsen
Keyword(s):  
Power Output ◽  
Whole Body Vibration ◽  
Sprint Performance ◽  
Whole Body ◽  
Sprint Training ◽  
Mean Power ◽  
Warm Up ◽  
Body Vibration ◽  
Mean Power Output ◽  
40 Hz

Postactivation-potentiation exercise with added whole-body vibration (WBV) has been suggested as a potential way to acutely improve sprint performance. In cycling, there are many competitions and situations where sprinting abilities are important.Purpose:To investigate the effect of adding WBV to warm-up procedures on subsequent cycle sprint performance.Methods:Eleven well-trained cyclists participated in the study. All cyclists performed a familiarization session before 2 separate test sessions in randomized order. Each session included a standardized warm-up followed by 1 of the following preconditioning exercises: 30 s of half-squats without WBV or 30 s of half-squats with WBV at 40 Hz. A 15-s Wingate sprint was performed 1 min after the preconditioning exercise.Results:Performing preconditioning exercise with WBV at 40 Hz resulted in superior peak power output compared with preconditioning exercise without WBV (1413 ± 257 W vs 1353 ± 213 W, P = .04) and a tendency toward superior mean power output during a 15-second all-out sprint (850 ± 119 W vs 828 ± 101 W, P = .08). Effect sizes showed a moderate practical effect of WBV vs no WBV on both peak and mean power output.Conclusions:Preconditioning exercise performed with WBV at 40 Hz seems to have a positive effect on cycling sprint performance in young well-trained cyclists. This suggests that athletes can incorporate body-loaded squats with WBV in preparations to specific sprint training to improve the quality of the sprint training and also to improve sprint performance in relevant competitions.

Reduced neuromuscular activity and force generation during prolonged cycling

2001 ◽  
Vol 281 (1) ◽  
pp. R187-R196 ◽  
Author(s):  
A. St Clair Gibson ◽  
E. J. Schabort ◽  
T. D. Noakes
Keyword(s):  
Power Output ◽  
High Intensity ◽  
Voluntary Contraction ◽  
Active Muscle ◽  
Mean Power ◽  
Variable Intensity ◽  
Neuromuscular Activity ◽  
Integrated Emg ◽  
The Mean ◽  
Mean Power Output

We examined neuromuscular activity during stochastic (variable intensity) 100-km cycling time trials (TT) and the effect of dietary carbohydrate manipulation. Seven endurance-trained cyclists performed two 100-km TT that included five 1-km and four 4-km high-intensity epochs (HIE) during which power output, electromyogram (EMG), and muscle glycogen data were analyzed. The mean power output of the 4-km HIE decreased significantly throughout the trial from 319 ± 48 W for the first 4-km HIE to 278 ± 39 W for the last 4-km HIE ( P < 0.01). The mean integrated EMG (IEMG) activity during the first 4-km HIE was 16.4 ± 9.8% of the value attained during the pretrial maximal voluntary contraction (MVC). IEMG decreased significantly throughout the trial, reaching 11.1 ± 5.6% during the last 4-km HIE ( P < 0.01). The study establishes that neuromuscular activity in peripheral skeletal muscle falls parallel with reduction in power output during bouts of high-intensity exercise. These changes occurred when <20% of available muscle was recruited and suggest the presence of a central neural governor that reduces the active muscle recruited during prolonged exercise.

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