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Effect of Environmental Temperature on High-Intensity Intervals in Well-Trained Cyclists

Jason R. Boynton, Fabian Danner, Paolo Menaspà, Jeremiah J. Peiffer, and Chris R. Abbiss

Purpose: To examine the effect of environmental temperature (T A) on performance and physiological responses (eg, body temperature, cardiopulmonary measures) during a high-intensity aerobic interval session. It was hypothesized that power output would be highest in the 13°C condition and lower in the 5°C, 22°C, and 35°C conditions. Methods: Eleven well-trained cyclists randomly completed 4 interval sessions at 5°C, 13°C, 22°C, and 35°C (55% [13%] relative humidity), each involving five 4-min intervals interspersed with 5 min of recovery. During the intervals, power output, core temperature (T C), skin temperature, VO2, and heart rate were recorded. Results: Mean session power output for 13°C (366 [32] W) was not higher than 5°C (363 [32] W; P = 1.00, effect size = 0.085), 22°C (364 [36] W; P = 1.00, effect size = 0.061), or 35°C (352 [31] W; P = .129, effect size = 0.441). The 5th interval of the 35°C condition had a lower power output compared with all other T A. T C was higher in 22°C compared with both 5°C and 13°C (P = .001). VO2 was not significantly different across T A (P = .187). Heart rate was higher in the 4th and 5th intervals of 35°C compared with 5°C and 13°C. Conclusions: This study demonstrates that while mean power outputs for intervals are similar across T A, hot T A (≥35°C) reduces interval power output later in a training session. Well-trained cyclists performing maximal high-intensity aerobic intervals can achieve near-optimal power output over a broader range of T A than previous literature would indicate.

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Influence of Pacing Manipulation on Performance of Juniors in Simulated 400-m Swim Competition

Sabrina Skorski, Oliver Faude, Chris R. Abbiss, Seraina Caviezel, Nina Wengert, and Tim Meyer

Purpose:

To date, there has been limited research examining the influence of pacing pattern (PP) on middle-distance swimming performance. As such, the purpose of the current study was to examine the influence of PP manipulation on 400-m freestyle swimming performance.

Methods:

15 front-crawl swimmers (5 female, 10 male; age 18 ± 2 y) performed 3 simulated 400-m swimming events. The initial trial was self-selected pacing (PPSS). The following 2 trials were performed in a counterbalanced order and required participants to complete the first 100 m more slowly (PPSLOW: 4.5% ± 2.2%) or quickly (PPFAST: 2.4% ± 1.6%) than the PPSS trial. 50-m split times were recorded during each trial.

Results:

Overall performance time was faster in PPSS (275.0 ± 15.9 s) than in PPFAST (278.5 ± 16.4 s, P = .05) but not significantly different from PPSLOW (277.5 ± 16.2 s, P = .22). However, analysis for practical relevance revealed that pacing manipulation resulted in a “likely” (>88.2%) decrease in performance compared with PPSS.

Conclusion:

Moderate manipulation of the starting speed during simulated 400-m freestyle races seems to affect overall performance. The observed results indicate that PPSS is optimal in most individuals, yet it seems to fail in some swimmers. Future research should focus on the identification of athletes possibly profiting from manipulations.

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Consistency of Commercial Devices for Measuring Elevation Gain

Paolo Menaspà, Franco M. Impellizzeri, Eric C. Haakonssen, David T. Martin, and Chris R. Abbiss

Purpose:

To determine the consistency of commercially available devices used for measuring elevation gain in outdoor activities and sports.

Methods:

Two separate observational validation studies were conducted. Garmin (Forerunner 310XT, Edge 500, Edge 750, and Edge 800; with and without elevation correction) and SRM (Power Control 7) devices were used to measure total elevation gain (TEG) over a 15.7-km mountain climb performed on 6 separate occasions (6 devices; study 1) and during a 138-km cycling event (164 devices; study 2).

Results:

TEG was significantly different between the Garmin and SRM devices (P < .05). The between-devices variability in TEG was lower when measured with the SRM than with the Garmin devices (study 1: 0.2% and 1.5%, respectively). The use of the Garmin elevation-correction option resulted in a 5–10% increase in the TEG.

Conclusions:

While measurements of TEG were relatively consistent within each brand, the measurements differed between the SRM and Garmin devices by as much as 3%. Caution should be taken when comparing elevation-gain data recorded with different settings or with devices of different brands.

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Hyperthermic Fatigue Precedes a Rapid Reduction in Serum Sodium in an Ironman Triathlete: A Case Report

Paul B. Laursen, Greig Watson, Chris R. Abbiss, Bradley A. Wall, and Kazunori Nosaka

Purpose:

To monitor the hydration, core temperature, and speed (pace) of a triathlete performing an Ironman triathlon.

Methods:

A 35-year-old experienced male triathlete participated in the Western Australian Ironman triathlon on December 1, 2006. The participant was monitored for blood Na+ concentration before the race (PRE), at the transitions (T1 and T2), halfway through the run (R21), and after the race (POST; 2hPOST). Core body temperature (T ; pill telemetry) was recorded continuously, and running speed (s3 stride sensor) was measured during the run.

Results:

The participant completed the race in 11 h 38 min, in hot conditions (26.6 ± 5.8°C; 42 ± 19% rel. humidity). His Tc increased from 37.0 to 38.6°C during the 57-min swim, and averaged 38.4°C during the 335-min bike (33.5 km·h-1). After running at 12.4 km·h-1 for 50 min in the heat (33.1°C), T increased to 39.4°C, before slowing to 10.0 km·h-1 for 20 min. T decreased to 38.9°C until he experienced severe leg cramps, after which speed diminished to 6 km·h-1 and T fell to 38.0°C. The athlete’s blood Na+ was constant from PRE to T2 (139-140 mEq·L-1, but fell to 131 mEq·L-1 at R21, 133 mEq·L-1 at POST, and 128 mEq·L-1at 2hPOST The athlete consumed 9.25 L of fuid from PRE to T2, 6.25 L from T2 to POST, and lost 2% of his body mass, indicating sweat losses greater than 15.5 L.

Conclusion:

This athlete slowed during the run phase following attainment of a critically high T and experienced an unusually rapid reduction in blood Na+ that preceded cramping, despite presenting with signs of dehydration.

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Carbohydrate Gel Ingestion and Immunoendocrine Responses to Cycling in Temperate and Hot Conditions

Jonathan Peake, Jeremiah J. Peiffer, Chris R. Abbiss, Kazunori Nosaka, Paul B. Laursen, and Katsuhiko Suzuki

Purpose:

Heat stress might attenuate the effects of carbohydrate on immunoendocrine responses to exercise by increasing endogenous glucose production and reducing the rate of exogenous carbohydrate oxidation. The authors compared the efficacy of carbohydrate consumption on immune responses to exercise in temperate vs. hot conditions.

Methods:

Ten male cyclists exercised on 2 separate occasions in temperate (18.1 ± 0.4 °C, 58% ± 8% relative humidity) and on another 2 occasions in hot conditions (32.2 ± 0.7 °C, 55% ± 2% relative humidity). On each occasion, the cyclists exercised in a fed state for 90 min at ~60% VO2max and then completed a 16.1-km time trial. Every 15 min during the first 90 min of exercise, they consumed 0.24 g/kg body mass of a carbohydrate or placebo gel.

Results:

Neutrophil counts increased during exercise in all trials (p < .05) and were significantly lower (40%, p = .006) after the carbohydrate than after the placebo trial in 32 °C. The concentrations of serum interleukin (IL)-6, IL-8, and IL-10 and plasma granulocyte-colony-stimulating factor, myeloperoxidase, and calprotectin also increased during exercise in all trials but did not differ significantly between the carbohydrate and placebo trials. Plasma norepinephrine concentration increased during exercise in all trials and was significantly higher (50%, p = .01) after the carbohydrate vs. the placebo trial in 32 °C.

Conclusion:

Carbohydrate ingestion attenuated neutrophil counts during exercise in hot conditions, whereas it had no effect on any other immune variables in either temperate or hot conditions.

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Difference in Pacing Between Time- and Distance-Based Time Trials in Trained Cyclists

Chris R. Abbiss, Kevin G. Thompson, Marcin Lipski, Tim Meyer, and Sabrina Skorski

The purpose of this study was to compare the pacing profiles between distance- and duration-based trials of short and long duration. Thirteen trained cyclists completed 2 time-based (6 and 30 min) and 2 distance-based (4 and 20 km) self-paced cycling time trials. Participants were instructed to complete each trial with the highest average power output. Ratings of perceived exertion (RPEs) were measured throughout the trials. Average power output was not different between the 4-km and 6-min trials (324 ± 46 vs 325 ± 45 W; P = .96) or between the 20-km and 30-min trials (271 ± 44 vs 267 ± 38 W; P = .24). Power output was greater on commencement of the distance-based trials when short and long trials were analyzed together. Furthermore, the rate of decline in power output over the 1st 40% of the trial was greater in the 20-km trial than in the 30-min trial (P = .01) but not different between the 4-km and the 6-min trials (P = .13). RPE was greater in the 4-km trial than in the 6-min trial but not different between the 20-km and 30-min trials. These findings indicate that athletes commenced distance-based time trials at relatively higher power outputs than a similar time-based trial. Such findings may result from discrete differences in our ability to judge or predict an exercise endpoint when performing time- and distance-based trials.

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Sprinting for the Win: Distribution of Power Output in Women’s Professional Cycling

Jeremiah J. Peiffer, Chris R. Abbiss, Eric C. Haakonssen, and Paolo Menaspà

Purpose: To examine the power-output distribution and sprint characteristics of professional female road cyclists. Methods: A total of 31 race files, representing top 5 finishes, were collected from 7 professional female cyclists. Files were analyzed for sprint characteristics, including mean and peak power output, velocity, and duration. The final 20 min before the sprint was analyzed to determine the mean maximal power output (MMP) consistent with durations of 5, 15, 30, 60, 240, and 600 s. Throughout the race, the number of efforts for each duration exceeding 80% of its corresponding final 20-min MMP (MMP80) was determined. The number of 15-s efforts exceeding 80% of the mean final sprint power output (MSP80) was determined. Results: Sprint finishes lasted 21.8 (6.7) s with mean and peak power outputs of 679 (101) and 886 (91) W, respectively. Throughout the race, additional 5-, 15-, and 30-s efforts above MMP80 were completed in the 5th compared with the 1st–4th quintiles of the race. The 60-s efforts were greater during the 5th quintile compared with the 1st, 2nd, and 4th quintiles, and during the 3rd compared with the 4th quintile. More 240-s efforts were recorded during the 5th compared with the 1st and 4th quintiles. About 82% of the 15-s efforts above MSP80 were completed in the 2nd, 3rd, and 5th quintiles of the race. Conclusions: These data demonstrate the variable nature of women’s professional cycling and the physical demands necessary for success, thus providing information that could enhance in-race decision making and the development of race-specific training programs.

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Power Output and Pacing During International Cross-Country Mountain Bike Cycling

Cyril Granier, Chris R. Abbiss, Anaël Aubry, Yvon Vauchez, Sylvain Dorel, Christophe Hausswirth, and Yann Le Meur

Purpose: To characterize the physiological profiles of elite cross-country mountain-bike (XCO-MTB) cyclists and to examine their pacing and power-output (PO) distribution during international races. Methods: Over 2 competitive seasons, 8 male XCO-MTB cyclists (VO2max 79.9 [5.2] mL·min−1·kg−1, maximal aerobic power [MAP] 411 [18] W and 6.3 [0.4] W·kg−1) regularly undertook incremental tests to assess their PO and heart rate (HR) at first and second ventilatory thresholds (VT1 and VT2) and at VO2max. During the same period, their PO, HR, speed, and cadence were recorded over 13 international races (total of 30 recorded files). Results: Mean PO, speed, cadence, and HR during the races were 283 (22) W (4.31 [0.32] W·kg−1, 68% [5%] MAP), 19.7 (2.1) km·h−1, 68 (8) rpm, and 172 (11) beats·min−1 (91% [2%] HRmax), respectively. The average times spent below 10% of MAP, between 10% of MAP and VT1, between VT1 and VT2, between VT2 and MAP, and above MAP were 25% (5%), 21% (4%), 13% (3%), 16% (3%), and 26% (5%), respectively. Both speed and PO decreased from the start loop to lap 1 before stabilizing until the end of the race. Conclusions: Elite off-road cyclists demonstrated typical values of world-class endurance cyclists with an excellent power-to-mass ratio. This study demonstrated that XCO-MTB races are performed at higher intensities than reported in previous research and are characterized by a fast start followed by an even pace.

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Blood-Flow Restriction Is Associated With More Even Pacing During High-Intensity Cycling

Nathan D.W. Smith, Chris R. Abbiss, Olivier Girard, Brendan R. Scott, and Jeremiah J. Peiffer

Purpose: This study examined the influence of blood-flow restriction (BFR) on the distribution of pace, physiological demands, and perceptual responses during self-paced cycling. Methods: On separate days, 12 endurance cyclists/triathletes were instructed to produce the greatest average power output during 8-minute self-paced cycling trials with BFR (60% arterial occlusion pressure) or without restriction (CON). Power output and cardiorespiratory variables were measured continuously. Perceived exertion, muscular discomfort, and cuff pain were recorded every 2 minutes. Results: Linear regression analysis of the power output slope was statistically significant (ie, deviated from the intercept) for CON (2.7 [3.2] W·30 s−1; P = .009) but not for BFR (−0.1 [3.1] W·30 s−1; P = .952). Absolute power output was ∼24% (12%) lower at all time points (P < .001) during BFR compared with CON. Oxygen consumption (18% [12%]; P < .001), heart rate (7% [9%]; P < .001), and perceived exertion (8% [21%]; P = .008) were reduced during BFR compared with CON, whereas muscular discomfort (25% [35%]; P = .003) was greater. Cuff pain was rated as “strong” (5.3 [1.8] au; 0–10 scale) for BFR. Conclusion: Trained cyclists adopted a more even distribution of pace when BFR was applied compared with a negative distribution during CON. By presenting a unique combination of physiological and perceptual responses, BFR is a useful tool to understand how the distribution of pace is self-regulated.

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Fluid Balance, Carbohydrate Ingestion, and Body Temperature During Men’s Stage-Race Cycling in Temperate Environmental Conditions

Megan L. Ross, Brian Stephens, Chris R. Abbiss, David T. Martin, Paul B. Laursen, and Louise M. Burke

Purpose:

To observe voluntary fluid and carbohydrate intakes and thermoregulatory characteristics of road cyclists during 2 multiday, multiple-stage races in temperate conditions.

Methods:

Ten internationally competitive male cyclists competed in 2 stage races (2009 Tour of Gippsland, T1, n = 5; 2010 Tour of Geelong, T2, n = 5) in temperate conditions (13.2–15.8°C; 54–80% relative humidity). Body mass (BM) was recorded immediately before and after each stage. Peak gastrointestinal temperature (TGI peak) was recorded throughout each stage. Cyclists recalled the types and volumes of fluid and food consumed throughout each stage.

Results:

Although fluid intake varied according to the race format, there were strong correlations between fluid intake and distance across all formats of racing, in both tours (r = .82, r = .92). Within a stage, the relationship between finishing time and fluid intake was trivial. Mean BM change over a stage was 1.3%, with losses >2% BM occurring on 5 out of 43 measured occasions and the fastest competitors incurring lower BM changes. Most subjects consumed carbohydrate at rates that met the new guidelines (30–60 g/h for 2–3 h, ~90 g/h for >3 h), based on event duration. There were consistent observations of TGI peak >39°C during stages of T1 (67%) and T2 (73%) despite temperate environmental conditions.

Conclusion:

This study captured novel effects of highintensity stage racing in temperate environmental conditions. In these conditions, cyclists were generally able to find opportunities to consume fluid and carbohydrate to meet current guidelines. We consistently observed high TGI peak, which merits further investigation.