The purpose of this study was to examine the effect of environmental temperature on variability in power output, self-selected pacing strategies, and performance during a prolonged cycling time trial. Nine trained male cyclists randomly completed four 40 km cycling time trials in an environmental chamber at 17°C, 22°C, 27°C, and 32°C (40% RH). During the time trials, heart rate, core body temperature, and power output were recorded. The variability in power output was assessed with the use of exposure variation analysis. Mean 40 km power output was significantly lower during 32°C (309 ± 35 W) compared with 17°C (329 ± 31 W), 22°C (324 ± 34 W), and 27°C (322 ± 32 W). In addition, greater variability in power production was observed at 32°C compared with 17°C, as evidenced by a lower (P = .03) standard deviation of the exposure variation matrix (2.9 ± 0.5 vs 3.5 ± 0.4 units, respectively). Core temperature was greater (P < .05) at 32°C compared with 17°C and 22°C from 30 to 40 km, and the rate of rise in core temperature throughout the 40 km time trial was greater (P < .05) at 32°C (0.06 ± 0.04°C·km–1) compared with 17°C (0.05 ± 0.05°C·km–1). This study showed that time-trial performance is reduced under hot environmental conditions, and is associated with a shift in the composition of power output. These finding provide insight into the control of pacing strategies during exercise in the heat.
Jeremiah J. Peiffer and Chris R. Abbiss
Cyril Schmit, Rob Duffield, Christophe Hausswirth, Aaron J. Coutts and Yann Le Meur
To describe the effect of the initial perceptual experience from heat familiarization on the pacing profile during a freepaced endurance time trial (TT) compared with temperate conditions.
Two groups of well-trained triathletes performed two 20-km TTs in either hot (35°C and 50% relative humidity [RH], n = 12) or temperate (21°C and 50% RH, n = 22) conditions, after standardization of training for each group before both trials. To ensure no physiological acclimation differences between conditions, the TTs for both groups were separated by 11 ± 4 d.
Performance improvement in the heat (11 ± 24 W) from the 1st to 2nd trial appeared comparable to that in temperate conditions (8 ± 14 W, P = .67). However, the specific alteration in pacing profile in the heat was markedly different than temperate conditions, with a change from “positive” to an “even” pacing strategy.
Altered perceptions of heat during heat familiarization, rather than physiological acclimatization per se, may mediate initial changes in pacing and TT performance in the heat. These results highlight the need for athletes without time for sufficient heat acclimatization to familiarize themselves with hot conditions to reduce the uncertainty from behavior-based outcomes that may impede performance.
Arthur H. Bossi, Guilherme G. Matta, Guillaume Y. Millet, Pedro Lima, Leonardo C. Pertence, Jorge P. de Lima and James G. Hopker
To describe pacing strategy in a 24-h running race and its interaction with sex, age group, athletes’ performance group, and race edition.
Data from 398 male and 103 female participants of 5 editions were obtained based on a minimum 19.2-h effective-running cutoff. Mean running speed from each hour was normalized to the 24-h mean speed for analyses.
Mean overall performance was 135.6 ± 33.0 km with a mean effective-running time of 22.4 ± 1.3 h. Overall data showed a reverse J-shaped pacing strategy, with a significant reduction in speed from the second-to-last to the last hour. Two-way mixed ANOVAs showed significant interactions between racing time and both athlete performance group (F = 7.01, P < .001, ηp 2 = .04) and race edition (F = 3.01, P < .001, ηp 2 = .02) but not between racing time and either sex (F = 1.57, P = .058, ηp 2 < .01) or age group (F = 1.25, P = .053, ηp 2 = .01). Pearson product–moment correlations showed an inverse moderate association between performance and normalized mean running speed in the first 2 h (r = –.58, P < .001) but not in the last 2 h (r = .03, P = .480).
While the general behavior represents a rough reverse J-shaped pattern, the fastest runners start at lower relative intensities and display a more even pacing strategy than slower runners. The “herd behavior” seems to interfere with pacing strategy across editions, but not sex or age group of runners.
Jonathan Esteve-Lanao, Eneko Larumbe-Zabala, Anouar Dabab, Alberto Alcocer-Gamboa and Facundo Ahumada
The aim of this study was to describe the pacing distribution during 6 editions of the world cross-country championships.
Data from the 768 male runners participating from 2007 to 2013 were considered for this study. Blocks of 10 participants according to final position (eg, 1st to 10th, 11 to 20th, etc) were considered.
Taking data from all editions together, the effect of years was found to be significant (F 5,266 = 3078.69, P < .001, ω2 = 0.31), as well as the effect of blocks of runners by final position (F 4,266 = 957.62, P < .001, ω2 = 0.08). A significant general decrease in speed by lap was also found (F 5,1330 = 2344.02, P < .001, ω2 = 0.29). Post hoc analyses were conducted for every edition where several pacing patterns were found. All correlations between the lap times and the total time were significant. However, each lap might show different predicting capacity over the individual outcome.
Top athletes seem to display different strategies, which allow them to sustain an optimal speed and/or kick as needed during the critical moments and succeed. After the first group (block) of runners, subsequent blocks always displayed a positive pacing pattern (fast to slow speed). Consequently, a much more stable pacing pattern should be considered to maximize final position.
Top-10 finishers in the world cross-country championships tend to display a more even pace than the rest of the finishers, whose general behavior shows a positive (fast-to-slow) pattern.
Sarah E. Scott, Jeff D. Breckon, Robert J. Copeland and Andrew Hutchison
Physical activity is promoted to help adults manage chronic health conditions, but evidence suggests that individuals relapse after intervention cessation. The objective of this study was to explore the determinants and strategies for successful and unsuccessful physical activity maintenance.
A qualitative study using semistructured interviews was conducted with 32 participants. Purposive sampling was used to recruit 20 successful and 12 unsuccessful maintainers. Adults with chronic health conditions were recruited having completed a physical activity referral scheme 6 months before study commencement. The IPAQ and SPAQ were used to categorize participants according to physical activity status. Data were analyzed using framework analysis.
Eleven main themes emerged: 1) outcome expectations, 2) experiences, 3) core values, 4) trial and error, 5) social and practical support, 6) attitudes toward physical activity, 7) environmental barriers, 8) psychological barriers, 9) physical barriers, 10) cognitive-behavioral strategies for physical activity self-management (eg, self-monitoring), and 11) condition management (eg, pacing).
The findings identified determinants and strategies for successful maintenance and highlighted the processes involved in physical activity disengagement. Such findings can guide the development of physical activity maintenance interventions and increase activity engagement over the long-term in adults with chronic health conditions.
Katherine T. Oberlin-Brown, Rodney Siegel, Andrew E. Kilding and Paul B. Laursen
The oral presence of carbohydrate (CHO) and caffeine (CAF) may independently enhance exercise performance, but their influence on performance during prolonged exercise is less known.
To determine the independent and combined effects of CHO and CAF administered in chewing gum during a cycling time trial (TT) after prolonged exercise.
Eleven male cyclists (32.2 ± 7.5 y, 74.3 ± 6.8 kg, 60.2 ± 4.0 mL · kg–1 · min–1 V˙O2peak) performed 4 experimental trials consisting of 90-min constant-load cycling at 80% of their second ventilatory threshold (207 ± 30 W), followed immediately by a 20-km TT. Under double-blinded conditions, cyclists received placebo (PLA), CHO, CAF, or a combined CHO+CAF chewing gum at 0-, 5-, 10-, and 15-km points of the TT.
Overall TT performance was similar across experimental and PLA trials (%mean difference ± 90%CL 0.2% ± 2.0%, 0.4% ± 2.2%, 0.1% ± 1.8% for CHO, CAF, and CHO+CAF). Compared with PLA, mean power output tended to be higher in the first 2 quarters of the TT with CHO (1.6% ± 3.1% and 0.8% ± 2.0%) and was substantially improved in the last 2 quarters during CAF and CHO+CAF trials (4.2% ± 3.0% and 2.0% ± 1.8%). There were no differences in average heart rate (ES <0.2) and only small changes in blood glucose (ES 0.2), which were unrelated to performance. Blood lactate was substantially higher post-TT for CAF and CHO+CAF (ES >0.6).
After prolonged constant-load cycling, the oral presence of CHO and CAF in chewing gum, independently or in combination, did not improve overall performance but did influence pacing.
Owen Jeffries, Mark Waldron, Stephen D. Patterson and Brook Galna
Pacing refers to an athlete’s distribution of work or energy across an event. 1 , 2 Athletes vary their physical output (ie, mechanical power output) to accommodate physiological or psychological constraints, for strategic racing purposes, or due to changing environmental factors. 2 , 3
Cyril Schmit, Rob Duffield, Christophe Hausswirth, Jeanick Brisswalter and Yann Le Meur
framework, the present study investigated the respective effects of either high- (HA-H) or low-intensity (HA-L) training sessions in the heat on self-paced endurance performance in well-trained athletes before and after a 1-week taper period. Methods Participants A total of 29 well-trained male triathletes
Angela Heidenfelder, Thomas Rosemann, Christoph A. Rüst and Beat Knechtle
To examine pacing strategies of ultracyclists competing in the Race Across AMerica (RAAM), the world’s longest ultracycling race, covering ~4860 km from the West to the East coast of America.
Age, cycling speed at and across time stations, race distance, relative difference in altitude between time stations, wind velocity, wind gradient, and temperature at each time station were recorded for women and men competing from 2010 to 2014. Changes in cycling speed and power output of elite and age-group finishers were analyzed using mixed-effects regression analyses.
Cycling speed decreased across time stations for women and men where men were faster than women. Power output decreased across time stations in women and men and was lower for women for all finishers, the annual 3 fastest, and age group 60–69 y but not for age groups 18–49 and 50–59 y. The change in temperature and altitude had an influence on cycling speed and power output in all finishers, the annual top 3, nonfinishers, and in all different age groups for both women and men but in the age group 50–59 y altitude had no influence on cycling speed.
Positive pacing (ie, decrease in speed throughout the race) seemed to be the adequate strategy in the RAAM. The top 3 finishers started faster and had a higher power output at the start than less successful competitors, achieved the highest peak cycling speeds and power output, and maintained peak cycling speed and power output longer before slowing down.
David N. Ellis, Pamela J. Cress and Charles R. Spellman
This report describes an effort to train adolescents and young adults with mental retardation to modify their rates of pedaling exercycles during 10-min self-paced exercise sessions in a public school setting using commercially available heart rate (HR) monitors. A signal sounded when participants’ heart rates fell outside their predetermined cardiorespiratory conditioning ranges. During Study 1 most participants consistently avoided the alarm by pedaling at rates that maintained their HRs above their criterion levels. Study 2 included a more intensive warm-up period on the treadmill. All subjects but one consistently responded to the signal, maintaining HRs within the criterion range. Two of the participants in Study 2 were exposed to a positive reinforcement condition, with music contingent on maintaining HRs above a preset lower limit. Two subjects participated in maintenance phases and continued to exhibit relatively high HRs during exercise in the absence of signals from the HR monitor.