Search Results

You are looking at 41 - 50 of 142 items for :

  • "peak power output" x
Clear All
Restricted access

David Montero and Carsten Lundby

Context:

Few recent studies indicate that short-term repeated-sprint (RS) training in hypoxia (RSH) improves RS performance compared with identical training under normoxic conditions (RSN) in endurance-trained subjects.

Purpose:

To determine the effects of RSH against RSN on RS performance under normoxic and moderate hypoxic conditions, using a randomized, doubleblind, crossover experimental design.

Methods:

Fifteen endurance-trained male subjects (age 25 ± 4 y) performed 4 wk of RS training (3 sessions/wk) in normobaric hypoxia (RSH, FiO2 = 13.8%) and normoxia (RSN, FiO2 = 20.9%) in a crossover manner. Before and after completion of training, RS tests were performed on a cycle ergometer with no prior exercise (RSNE), after an incremental exercise test (RSIE), and after a time-trial test (RSTT) in normoxia and hypoxia.

Results:

Peak power outputs at the incremental exercise test and time-trial performance were unaltered by RSH in normoxia and hypoxia. RS performance was generally enhanced by RSH, as well as RSN, but there were no additional effects of RSH over RSN on peak and mean sprint power output and the number of repeated sprints performed in the RSNE, RSIE, and RSTT trials under normoxic and hypoxic conditions.

Conclusions:

The present double-blind crossover study indicates that RSH does not improve RS performance compared with RSN in normoxic and hypoxic conditions in endurance-trained subjects. Therefore, caution should be exercised when proposing RSH as an advantageous method to improve exercise performance.

Restricted access

Julia H. Goedecke, Virginia R. Clark, Timothy D. Noakes and Estelle V. Lambert

The aims of the study were to determine if medium-chain triacylglycerol (MCT), ingested in combination with carbohydrate (CHO), would alter substrate metabolism and improve simulated competitive ultra-endurance cycling performance. Eight endurance-trained cyclists took part in this randomized, single-blind crossover study. On two separate occasions, subjects cycled for 270 min at 50% of peak power output, interspersed with four 75 kJ sprints at 60 min intervals, followed immediately by a 200 kJ time-trial. One hour prior to the exercise trials, subjects ingested either 75 g of CHO or 32 g of MCT, and then ingested 200 mL of a 10% CHO (wt/vol) solution or a 4.3% MCT + 10% CHO (wt/vol) solution every 20 min during the CHO and MCT trials, respectively. During the constant-load phases of the 270 min exercise trial, VO2, RER, and heart rate were measured at 30 min intervals and gastrointestinal (GI) symptoms were recorded. There was no difference in VO2 or RER between the MCT and CHO trials (P = 0.40). Hourly sprint (P = 0.03 for trial x time interaction) and time-trial times (14:30 ± 0.58 vs. 12:36 ± 1:6, respectively, P < 0.001) were slower in the MCT than the CHO trial. Half the subjects experienced GI symptoms with MCT ingestion. In conclusion, MCTs ingested prior to exercise and co-ingested with CHO during exercise did not alter substrate metabolism and significantly compromised sprint performance during prolonged ultra-endurance cycling exercise.

Restricted access

Iker Leoz-Abaurrea, Mikel Izquierdo, Miriam Gonzalez-Izal and Roberto Aguado-Jiménez

The efficacy of the use of an upper body compression garment (UBCG) as an ergogenic aid to reduce thermoregulatory strain in older adults remains unknown. The aim of this study was to evaluate the effects of UBCG on thermoregulatory, cardiorespiratory, and perceptual responses during cycling in a temperate environment (~25 °C, 66% rh) in trained older adults. Twelve cyclists aged 66 ± 2 years performed an intermittent 1-hr cycling trial at 50% of the peak power output followed by 10 min of passive recovery. Participants were provided with either commercially available UBCG or a control garment in a randomized order. UBCG increased thermoregulatory strain during exercise, as indicated by a significantly higher core temperature (38.1 ± 0.3 °C vs. 37.9 ± 0.3 °C; p = .04), body temperature (36.9 ± 0.2 °C vs. 36.7 ± 0.2 °C; p = .01), and thermal sensation (8.0 ± 0.4 vs. 7.5 ± 1.0; p = .02). These results suggest that the use of UBCG in trained older adults does not reduce the thermoregulatory strain during moderate exercise.

Restricted access

Joseph A. McQuillan, Deborah K. Dulson, Paul B. Laursen and Andrew E. Kilding

We aimed to compare the effects of two different dosing durations of dietary nitrate (NO3 -) supplementation on 1 and 4 km cycling time-trial performance in highly trained cyclists. In a double-blind crossover-design, nine highly trained cyclists ingested 140ml of NO3 --rich beetroot juice containing ~8.0mmol [NO3 -], or placebo, for seven days. Participants completed a range of laboratory-based trials to quantify physiological and perceptual responses and cycling performance: time-trials on day 3 and 6 (4km) and on day 4 and 7 (1km) of the supplementation period. Relative to placebo, effects following 3- and 4-days of NO3 - supplementation were unclear for 4 (-0.8; 95% CL, ± 2.8%, p = .54) and likely harmful for 1km (-1.9; ± 2.5% CL, p = .17) time-trial mean power. Effects following 6- and 7-days of NO3 - supplementation resulted in unclear effects for 4 (0.1; ± 2.2% CL, p = .93) and 1km (-0.9; ± 2.6%CL, p = .51) time-trial mean power. Relative to placebo, effects for 40, 50, and 60% peak power output were unclear for economy at days 3 and 6 of NO3 - supplementation (p > .05). Dietary NO3 - supplementation appears to be detrimental to 1km time-trial performance in highly trained cyclists after 4-days. While, extending NO3 - dosing to ≥ 6-days reduced the magnitude of harm in both distances, overall performance in short duration cycling time-trials did not improve relative to placebo.

Restricted access

Alannah Quinlivan, Christopher Irwin, Gary D. Grant, Sheilandra Anoopkumar-Dukie, Tina Skinner, Michael Leveritt and Ben Desbrow

This study investigated the ergogenic effects of a commercial energy drink (Red Bull) or an equivalent dose of anhydrous caffeine in comparison with a noncaffeinated control beverage on cycling performance. Eleven trained male cyclists (31.7 ± 5.9 y 82.3 ± 6.1 kg, V̇O2max = 60.3 ± 7.8 mL · kg–1 · min–1) participated in a double-blind, placebo-controlled, crossover-design study involving 3 experimental conditions. Participants were randomly administered Red Bull (9.4 mL/kg body mass [BM] containing 3 mg/kg BM caffeine), anhydrous caffeine (3 mg/kg BM given in capsule form), or a placebo 90 min before commencing a time trial equivalent to 1 h cycling at 75% peak power output. Carbohydrate and fluid volumes were matched across all trials. Performance improved by 109 ± 153 s (2.8%, P = .039) after Red Bull compared with placebo and by 120 ± 172 s (3.1%, P = .043) after caffeine compared with placebo. No significant difference (P > .05) in performance time was detected between Red Bull and caffeine treatments. There was no significant difference (P > .05) in mean heart rate or rating of perceived exertion among the 3 treatments. This study demonstrated that a moderate dose of caffeine consumed as either Red Bull or in anhydrous form enhanced cycling time-trial performance. The ergogenic benefits of Red Bull energy drink are therefore most likely due to the effects of caffeine, with the other ingredients not likely to offer additional benefit.

Restricted access

Bent R. Rønnestad, Gunnar Slettaløkken Falch and Stian Ellefsen

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.

Restricted access

Kevin De Pauw, Bart Roelands, Stephen S. Cheung, Bas de Geus, Gerard Rietjens and Romain Meeusen

Purpose:

The aim of this systematic literature review was to outline the various preexperimental maximal cycle-test protocols, terminology, and performance indicators currently used to classify subject groups in sportscience research and to construct a classification system for cycling-related research.

Methods:

A database of 130 subject-group descriptions contains information on preexperimental maximal cycle-protocol designs, terminology of the subject groups, biometrical and physiological data, cycling experience, and parameters. Kolmogorov-Smirnov test, 1-way ANOVA, post hoc Bonferroni (P < .05), and trend lines were calculated on height, body mass, relative and absolute maximal oxygen consumption (VO2max), and peak power output (PPO).

Results:

During preexperimental testing, an initial workload of 100 W and a workload increase of 25 W are most frequently used. Three-minute stages provide the most reliable and valid measures of endurance performance. After obtaining data on a subject group, researchers apply various terms to define the group. To solve this complexity, the authors introduced the neutral term performance levels 1 to 5, representing untrained, recreationally trained, trained, well-trained, and professional subject groups, respectively. The most cited parameter in literature to define subject groups is relative VO2max, and therefore no overlap between different performance levels may occur for this principal parameter. Another significant cycling parameter is the absolute PPO. The description of additional physiological information and current and past cycling data is advised.

Conclusion:

This review clearly shows the need to standardize the procedure for classifying subject groups. Recommendations are formulated concerning preexperimental testing, terminology, and performance indicators.

Restricted access

Mark Hayes, Paul C. Castle, Emma Z. Ross and Neil S. Maxwell

Purpose:

To examine the effect of a hot humid (HH) compared with a hot dry (HD) environment, matched for heat stress, on intermittent-sprint performance. In comparison with HD, HH environments compromise evaporative heat loss and decrease exercise tolerance. It was hypothesized that HH would produce greater physiological strain and reduce intermittent-sprint exercise performance compared with HD.

Method:

Eleven male team-sport players completed the cycling intermittent-sprint protocol (CISP) in 3 conditions, temperate (TEMP; 21.2°C ± 1.3°C, 48.6% ± 8.4% relative humidity [rh]), HH (33.7°C ± 0.5°C, 78.2% ± 2.3% rh), and HD (40.2°C ± 0.2°C, 33.1% ± 4.9% rh), with both heat conditions matched for heat stress.

Results:

All participants completed the CISP in TEMP, but 3 failed to completed the full protocol of 20 sprints in HH and HD. Peak power output declined in all conditions (P < .05) but was not different between any condition (sprints 1–14 [N = 11]: HH 1073 ± 150 W, HD 1104 ± 127 W, TEMP, 1074 ± 134; sprints 15–20 [N = 8]: HH 954 ± 114 W, HD 997 ± 115 W, TEMP 993 ± 94; P > .05). Physiological strain was not significantly different in HH compared with HD, but HH was higher than TEMP (P < .05).

Conclusion:

Intermittent-sprint exercise performance of 40 min duration is impaired, but it is not different in HH and HD environments matched for heat stress despite evidence of a trend toward greater physiological strain in an HH environment.

Restricted access

Geoff Minett, Rob Duffield and Stephen P. Bird

Purpose:

To investigate the effects of an acute multinutrient supplement on game-based running performance, peak power output, anaerobic by-products, hormonal profiles, markers of muscle damage, and perceived muscular soreness before, immediately after, and 24 h following competitive rugby union games.

Methods:

Twelve male rugby union players ingested either a comprehensive multinutrient supplement (SUPP), [RE-ACTIVATE:01], or a placebo (PL) for 5 d. Participants then performed a competitive rugby union game (with global positioning system tracking), with associated blood draws and vertical jump assessments pre, immediately post and 24 h following competition.

Results:

SUPP ingestion resulted in moderate to large effects for augmented 1st half very high intensity running (VHIR) mean speed (5.9 ± 0.4 vs 4.8 ± 2.3 m·min−1; d = 0.93). Further, moderate increases in 2nd half VHIR distance (137 ± 119 vs 83 ± 89 m; d = 0.73) and VHIR mean speed (5.9 ± 0.6 v 5.3 ± 1.7 m·min−1; d = 0.56) in SUPP condition were also apparent. Postgame aspartate aminotransferase (AST; 44.1 ± 11.8 vs 37.0 ± 3.2 UL; d = 1.16) and creatine kinase (CK; 882 ± 472 vs. 645 ± 123 UL; d = 0.97) measures demonstrated increased values in the SUPP condition, while AST and CK values correlated with 2nd half VHIR distance (r = −0.71 and r = −0.76 respectively). Elevated C-reactive protein (CRP) was observed postgame in both conditions; however, it was significantly blunted with SUPP (P = .05).

Conclusions:

These findings suggest SUPP may assist in the maintenance of VHIR during rugby union games, possibly via the buffering qualities of SUPP ingredients. However, correlations between increased work completed at very high intensities and muscular degradation in SUPP conditions, may mask any anticatabolic properties of the supplement.

Restricted access

Jonathan. P. Little, Scott C. Forbes, Darren G. Candow, Stephen M. Cornish and Philip D. Chilibeck

Creatine (Cr) supplementation increases muscle mass, strength, and power. Arginine α-ketoglutarate (A-AKG) is a precursor for nitric oxide production and has the potential to improve blood flow and nutrient delivery (i.e., Cr) to muscles. This study compared a commercial dietary supplement of Cr, A-AKG, glutamine, taurine, branchedchain amino acids, and medium-chain triglycerides with Cr alone or placebo on exercise performance and body composition. Thirty-five men (~23 yr) were randomized to Cr + A-AKG (0.1 g · kg−1 · d−1 Cr + 0.075 g · kg−1 · d−1 A-AKG, n = 12), Cr (0.1 g · kg−1 · d−1, n = 11), or placebo (1 g · kg−1 · d−1 sucrose, n = 12) for 10 d. Body composition, muscle endurance (bench press), and peak and average power (Wingate tests) were measured before and after supplementation. Bench-press repetitions over 3 sets increased with Cr + A-AKG (30.9 ==6.6 → 34.9 ± 8.7 reps; p < .01) and Cr (27.6 ± 5.9 → 31.0 ± 7.6 reps; p < .01), with no change for placebo (26.8 ± 5.0 → 27.1 ± 6.3 reps). Peak power significantly increased in Cr + A-AKG (741 ± 112 → 794 ± 92 W; p < .01), with no changes in Cr (722 ± 138 → 730 ± 144 W) and placebo (696 ± 63 → 705 ± 77 W). There were no differences in average power between groups over time. Only the Cr-only group increased total body mass (79.9 ± 13.0→81.1 ± 13.8 kg; p < .01), with no significant changes in lean-tissue or fat mass. These results suggest that Cr alone and in combination with A-AKG improves upper body muscle endurance, and Cr + A-AKG supplementation improves peak power output on repeated Wingate tests.