Reliability of a protocol for testing endurance performance in runners and cyclists

What is a cycling race simulation anyway: a review on protocols to assess durability in cycling

Physiological resilience or durability is now recognised as a determinant of endurance performance such as road cycling. Reliable, ecologically valid and standardised performance tests in laboratory-based cycling protocols have to be established to investigate mechanisms underpinning, and interventions improving durability. This review aims to provide an overview of available race simulation protocols in the literature and examines its rigour around themes that influence durability including (i) exercise intensity anchoring and (ii) carbohydrate intake whilst also (iii) inspecting reliability and justification of the developed protocols. Using a systematic search approach, 48 articles were identified that met our criteria as a cycling race simulation. Most protocols presented limitations to be recommended as exercise test to investigate durability, such as not appropriately addressing the influence of exercise intensity domains by anchoring exercise intensity as % peak power or % V ˙ O2max. Ten articles provided reliability data, but only one articles under the appropriate conditions. Most studies sufficiently controlled nutrition during trials but not in the days leading to the trials or just before the trials. Thus, there is a paucity in protocols that combine justification and reliability with optimal nutritional support and mimic the true demands of a road-cycling race. This review lists an overview of protocols that researchers could use with caution to select a protocol for future experiments, but encourages further development of improved protocols, including utilisation of virtual software applications.

Effects of body-mapping-designed clothing on heat stress and running performance in a hot environment

To investigate clothing-induced differences in human thermal response and running performance, eight male athletes participated in a repeated-measure study by wearing three sets of clothing (CloA, CloB, and CloC). CloA and CloB were body-mapping-designed with 11% and 7% increased capacity of heat dissipation respectively than CloC, the commonly used running clothing. The experiments were conducted by using steady-state running followed by an all-out performance running in a controlled hot environment. Participants' thermal responses such as core temperature (T_c), mean skin temperature ([Formula: see text]), heat storage (S), and the performance running time were measured. CloA resulted in shorter performance time than CloC (323.1 ± 10.4 s vs. 353.6 ± 13.2 s, p = 0.01), and induced the lowest [Formula: see text], smallest ΔT_c, and smallest S in the resting and running phases. This study indicated that clothing made with different heat dissipation capacities affects athlete thermal responses and running performance in a hot environment. Practitioner Summary: A protocol that simulated the real situation in running competitions was used to investigate the effects of body-mapping-designed clothing on athletes' thermal responses and running performance. The findings confirmed the effects of optimised clothing with body-mapping design and advanced fabrics, and ensured the practical advantage of developed clothing on exercise performance.

Intra-Subject Variability of 5 km Time Trial Performance Completed by Competitive Trained Runners

Time-trials represent an ecologically valid approach to assessment of endurance performance. Such information is useful in the application of testing protocols and estimation of sample sizes required for research/magnitude based inference methods. The present study aimed to investigate the intra-subject variability of 5 km time-trial running performance in trained runners. Six competitive trained male runners (age = 33.8 ± 10.1 years; stature = 1.78 ± 0.01 m; body mass = 69.0 ± 10.4 kg, V.O_2max = 62.6 ± 11.0 ml·kg·min^-1) completed an incremental exercise test to volitional exhaustion followed by 5 x 5 km time-trials (including a familiarisation trial), individually spaced by 48 hours. The time taken to complete each trial, heart rate, rating of perceived exertion and speed were all assessed. Intra-subject absolute standard error of measurement and the coefficient of variance were calculated for time-trial variables in addition to the intra-class correlation coefficient for time taken to complete the time-trial. For the primary measure time, results showed a coefficient of variation score across all participants of 1.5 ± 0.59% with an intra-class correlation coefficient score of 0.990. Heart rate, rating of perceived exertion and speed data showed a variance range between 0.8 and 3.05%. It was concluded that when compared with related research, there was observed low intra-subject variability in trained runners over a 5 km distance. This supports the use of this protocol for 5 km time-trial performance for assessment of nutritional strategies, ergogenic aids or training interventions on endurance running performance.

Increases in cycling performance in response to caffeine ingestion are repeatable

The primary aim of this study was to determine the repeatability of caffeine's ergogenic effects on cycling performance. It was hypothesized that improvements in performance would be similar when caffeine was ingested on 2 separate days. Nine endurance-trained men and women (mean age and maximal oxygen uptake, 27.4 ± 5.9 years and 57.5 ± 3.9 mL kg⁻¹ min⁻¹) initially completed 2 familiarization trials. During 3 subsequent sessions separated by at least 48 hours, the subjects completed a 10-km cycling time trial preceded by ingestion of a drink containing caffeine (5 mg/kg) or placebo. Treatments were ingested using a randomized, single-blind, crossover design, and the subjects were deceived as to the specific content of all drinks. During exercise, heart rate, rating of perceived exertion, and time were recorded every 1.6 km. Repeated-measures analysis of variance was used to compare the differences in variables across distance and treatment. In both caffeine trials, caffeine increased (P = .02) cycling performance by 1.6% and 1.9% vs placebo (16.98 ± 0.96 and 16.92 ± 0.97 minutes with caffeine vs 17.25 ± 0.96 minutes in placebo), and 7 of 9 subjects revealed improved performance. The mean performance improvement in the caffeine trials was similar (P = .35; -0.27 and -0.32 minutes, respectively) across days. Heart rate during exercise was higher (P b .001) with caffeine vs placebo, although the rating of perceived exertion was similar (P = .65). Data reveal that caffeine's ergogenic effects on cycling performance are repeatable across days, yet some individuals did not exhibit improved performance with caffeine.

Effect of a carbohydrate mouthwash on running time-trial performance

The aim of the present study was to determine the effect of a carbohydrate mouthwash on running time-trial performance. On two separate occasions, seven recreationally active males (VO2max 57.8 ml x kg(-1) x min(-1), s = 3.7) completed a preloaded (15 min at 65%VO2max) time-trial of 45 min in duration on a motorized treadmill. At 6-min intervals during the preload and time-trial, participants were given either a 6% maltodextrin, 3% lemon juice solution (carbohydrate trial) or a 3% lemon juice placebo mouthwash (placebo trial) in a double-blind, randomized crossover design. Heart rate, oxygen consumption (VO2), respiratory exchange ratio (RER), and ratings of perceived exertion (RPE) were measured during the preload, and blood glucose and lactate were measured before and after the preload and time-trial. There were no significant differences in distance covered between trials (carbohydrate: 9333 m, s = 988; placebo: 9309 m, s = 993). Furthermore, there were no significant between-trial differences in heart rate and running speed during the time-trial, or VO2, RER or RPE during the preload. Blood lactate and glucose increased as a result of the exercise protocol, with no between-trial differences. In conclusion, there was no positive effect of a carbohydrate mouthwash on running performance of approximately 1 h duration.

The reproducibility of an endurance performance test in adolescent cyclists

The purpose of the study was to measure the reproducibility of a performance test in well-trained adolescent cyclists. Eight male and one female cyclist [mean age 15.7 (0.7) y] participated in the study. Lactate threshold (LT) and peak VO2 were assessed. The performance test was repeated on three separate days and consisted of 30 min of steady state (SS) cycling at 80% of individual LT. Immediately after the SS cycling a time trial (TT) started with the cyclists having to complete a fixed amount of work as fast as possible. Reliability was assessed for the TT with the coefficient of variation (CV) as the (SD/mean)*100 for each participant, intraclass correlation coefficients (ICC) and typical error (SD of the difference in mean /radical2). The group mean (SD) times for the TT were TT1 1889 (306), TT2 1857 (283) and TT3 1953 (279) s respectively. Individual CV varied from 0.25% to 10%. The ICC for TT1/2 and 2/3 were r = 0.78 and 0.93 (P<0.05). The typical errors, expressed as a CV% on the log transformed performance times, were 7.3 and 3.7% for TT1/2 and TT2/3 respectively. The largest individual CVs were observed between TT1 and TT2. The differences in CV and SD among the three TTs indicate that trial two and three were more reliable than TT1, suggesting a habituation trial is needed. It is concluded that the present performance test is reliable in adolescent cyclists with lower variation between trials 2 and 3.

Reproducibility of Endurance Performance on a Treadmill Using a Preloaded Time Trial

PURPOSE

The purpose of this study was to establish a highly reproducible test to measure endurance performance in runners.

METHODS

We evaluated the reproducibility of endurance performance during a 10-km time trial performed on a treadmill after a 90-min preload run at 65% of maximal oxygen uptake VO2max). After screening and a practice test, eight endurance runners (4 men, 4 women, 33.4 +/- 10.1 yr, VO2max = 60.3 +/- 6.3 mL x kg(-1) x min(-1) in men and 51.8 +/- 2.2 mL x kg(-1) x min(-1) in women, mean +/- SD) completed two preloaded time trial tests spaced 3-4 wk apart in men and one menstrual cycle apart in women. A high-carbohydrate diet (15% protein, 10% fat, 75% carbohydrate) was provided the day before both tests.

RESULTS

Runners completed time trial 1 and time trial 2 in 45:41 +/- 4:45 and 45:24 +/- 5:03 min:s, respectively (43:29 +/- 5:02 and 43:12 +/- 5:14 min:s for men and 47:53 +/- 3:47 and 47:35 +/- 4:23 min:s for women, trials 1 and 2, respectively). The within-subject coefficient of variation for 10-km time was 1.00% +/- 0.25% (point estimate +/- estimated standard error) (0.54% +/- 0.19% for men and 1.26% +/- 0.45% for women).

CONCLUSION

These results suggest that performance measured as time to complete a 10-km time trial on a treadmill after a 90-min preload is extremely reliable and may be useful for future research assessing the effect of diet, ergogenic substances, or training methods on endurance running performance.

Reliability of power in physical performance tests

The reliability of power in tests of physical performance affects the precision of assessment of athletes, patients, clients and study participants. In this meta-analytic review we identify the most reliable measures of power and the factors affecting reliability. Our measures of reliability were the typical (standard) error of measurement expressed as a coefficient of variation (CV) and the percent change in the mean between trials. We meta-analysed these measures for power or work from 101 studies of healthy adults. Measures and tests with the smallest CV in exercise of a given duration include field tests of sprint running (approximately 0.9%), peak power in an incremental test on a treadmill or cycle ergometer (approximately 0.9%), equivalent mean power in a constant-power test lasting 1 minute to 3 hours on a treadmill or cycle ergometer (0.9 to 2.0%), lactate-threshold power (approximately 1.5%), and jump height or distance (approximately 2.0%). The CV for mean power on isokinetic ergometers was relatively large (> 4%). CV were larger for nonathletes versus athletes (1.3 x), female versus male nonathletes (1.4 x), shorter (approximately 1-second) and longer (approximately 1-hour) versus 1-minute tests (< or = 1.6 x), and respiratory- versus ergometer-based measures of power (1.4 to 1.6 x). There was no clear-cut effect of time between trials. The importance of a practice trial was evident in studies with > 2 trials: the CV between the first 2 trials was 1.3 times the CV between subsequent trials; performance also improved by 1.2% between the first 2 trials but by only 0.2% between subsequent trials. These findings should help exercise practitioners and researchers select or design good measures and protocols for tests of physical performance.

Effect of bright light on cycling performance

PURPOSE

The purpose of this study was to examine the effect of exposure to three levels of light intensity during cycling on average power output during an all-out 20-min bout of cycle ergometry.

METHODS

Twelve male competitive cyclists, with a mean age of 24.3 +/- 3.2 yr, were tested on four separate occasions. During each test session, participants were instructed to produce the highest possible average power output during a 20-min bout of cycle ergometry. Session 1 served as a adaptation trial and was conducted in normal room lighting (approximately 250 lux). In subsequent sessions each participant exercised while sitting in front of a light box. Light intensity was experimentally manipulated through the use of sunglasses that provided high, medium, and low light filtration. Light condition order was counterbalanced. Measurements of heart rate, muscle pain, local perceived exertion, metabolism, and alertness were made during exercise. Mood was assessed before and following exercise with the POMS-BI.

RESULTS

There were no statistically significant differences in the average total power output in the 1,411 lux (274.9 +/- 21.8 W), 2,788 lux (274.4 +/- 20.5 W), and 6,434 lux (270.3 +/- 19.8 W) light conditions. The difference between the average power output in the brightest and least bright condition (4.6 W) was approximately one-fourth of a pooled SD (d = 0.22). There were no significant differences among the conditions in alertness, leg muscle pain, perceived exertion, heart rate, VO2, or mood responses to the exercise.

CONCLUSION

It is concluded that exposure to bright light resulting in estimated retinal exposures ranging from 1,411 to 6,434 lux did not have a large or systematic influence on the performance of 20 min of maximal cycle ergometry.