Cycling Time Trial Performance Research Articles

Phosphate Loading Does not Improve 30-km Cycling Time-Trial Performance in Trained Cyclists

Phosphate is integral to numerous metabolic processes, several of which strongly predict exercise performance (i.e.,cardiac function, oxygen transport, and oxidative metabolism). Evidence regarding phosphate loading is limited and equivocal, at least partly because studies have examined sodium phosphate supplements of varied molar mass (e.g.,mono/di/tribasic, dodecahydrate), thus delivering highly variable absolute quantities of phosphate. Within a randomized cross-over design and in a single-blind manner, 16 well-trained cyclists (age 38 ± 16years, mass 74.3 ± 10.8kg, training 340 ± 171min/week; mean ± SD) ingested either 3.5g/day of dibasic sodium phosphate (Na2HPO4: 24.7mmol/day phosphate; 49.4mmol/day sodium) or a sodium chloride placebo (NaCl: 49.4mmol/day sodium and chloride) for 4days prior to each of two 30-km time trials, separated by a washout interval of 14days. There was no evidence of any ergogenic benefit associated with phosphate loading. Time to complete the 30-km time trial did not differ following ingestion of sodium phosphate and sodium chloride (3,059 ± 531s vs. 2,995 ± 467s). Accordingly, neither absolute mean power output (221 ± 48 W vs. 226 ± 48W) nor relative mean power output (3.02 ± 0.78W/kg vs. 3.08 ± 0.71W/kg) differed meaningfully between the respective intervention and placebo conditions. Measures of cardiovascular strain and ratings of perceived exertion were very closely matched between treatments (i.e.,average heart rate 161 ± 11beats per minute vs. 159 ± 12 beats per minute; Δ2beats per minute; and ratings of perceived exertion 18 [14-20]units vs. 17 [14-20] units). In conclusion, supplementing with relatively high absolute doses of phosphate (i.e.,>10mmol daily for 4days) exerted no ergogenic effects on trained cyclists completing 30-km time trials.

Acute Consumption of New Zealand Blackcurrant Extract Has No Effect on Cycling Performance in Normobaric Hypoxia with Trained Cyclists

Introduction: New Zealand Blackcurrant Extract (NZBC) is a popular ergogenic aid used to improve endurance performance. The aim of this research was to determine the effects of a single bolus of NZBC on 10-km time trial (TT) cycling performance in normobaric hypoxia. Methods: A double-blind, crossover design study was conducted with trained cyclists. The effects of acute NZBC (900 mg) were compared with a placebo in normobaric hypoxia (NH) (FiO2 = 15.5%). Testing comprised of three laboratory-based visits for (1) familiarisation (and screening of TT performance before entry into study), (2) placebo and (3) NZBC, whereby a 10-km cycling TT was completed one hour after consumption. After completion of the TT blood lactate was assessed at four time-points in the 10 minutes following. Throughout the TT, power output (PO), rating of perceived exertion (RPE) and heart rate (HR) were recorded. Results: NZBC had no effect on TT cycling performance in NH compared to a placebo (1078.4 s [1009.4, 1147.4] and 1071.0 s [1006.4, 1137.5] respectively, p=0.31; d=-0.31). Additionally, no difference was observed for mean power output (p=0.20; d=0.39), HR (p=0.76; d=0.09) or at 1-km intervals for performance time (p=0.80), PO (p=0.77) or RPE (p=0.41). Post exercise blood lactate recovery did not differ between placebo and NZBC (p=0.42). Conclusion: Acute intake of NZBC has no effect on cycling performance or blood lactate recovery in simulated altitude.

Time Trial positioning in elite cyclists - exploring the physiological effects of adapting to a lower torso position

Lowering of the upper body to optimize cycling time trial (TT) performance is a balance between the aerodynamic advantage related to a lower frontal area and prospective detrimental physiological effects associated with a reduction of the hip-torso angle. To explore this in elite athletes and across positions relevant for competitive cyclists, we analysed racing positions for world championships [WC] top-10 finishers and 10 national elite TT-cyclists. Subsequently, laboratory studies were completed to evaluate effects on exercise economy, muscle oxygenation and perceived exertion for the national TT-group for their habitual position and compared to standard (4-12-20˚) torso angles. Hence, covering the racing position observed for top-10 WC finishers (positioned from 4-12˚) and the national elite (range 8-18˚). Oxygen calorimetry and near-infrared spectroscopy revealed that there was no difference in overall energy expenditure, delta exercise efficiency or muscle oxygenation across the investigated range of positions. However, rating of perceived exertion was significantly elevated for the lowest position (4˚ torso angle) compared to the rider’s habitual position. This lets us conclude that elite TT-cyclists can acutely adopt to a very low upper body position without compromising exercise economy or muscle oxygenation and some WC-level TT riders have adopted this low (4˚) racing position. However, the elevated perception of exertion with an acute reduction of the torso-hip angle indicates that it presumably requires specific training in the position or factors not related to exercise economy and muscle oxygenation determine if a rider in practice can perform in the very low position.

Effects of mixed-method cooling between exercise bouts on thermoregulation and cycling time-trial performance in the heat

This study investigated the effects of mixed-method cooling during a short break between exercise bouts on thermoregulation and cycling time-trial (TT) performance in the heat. In a randomized crossover design, nine physically active men performed two 30-min cycling bouts that consisted of 25-min constant-paced cycling at 55% of maximal oxygen uptake followed by a 5-min TT in the heat (35 °C, 50% relative humidity). The two bouts were separated by a 15-min break. During the break, participants were assigned to a control trial (CON; 5 g kg−1 fluid ingestion at room temperature) or a mixed-method cooling trial (COOL; 5 g kg−1 ice slurry ingestion and cooling vest to cool the neck and torso). Physiological (rectal [Tre], forehead deep-tissue [Tdeep-head], mean skin [T‾sk], forehead skin [Thead], and neck skin [Tneck] temperatures, heart rate [HR], and skin blood flow [SkBF]) and perceptual data (ratings of perceived exertion [RPE], thermal comfort [TC], and thermal sensation [TS]) were measured. At the end of the 15-min break, Tdeep-head (−0.5 ± 0.2 °C, p < 0.001), T‾sk (−5.6 ± 3.1 °C, p = 0.001), Thead (−0.8 ± 0.4 °C, p = 0.001), Tneck (−9.8 ± 6.0 °C, p = 0.002), HR (−17 ± 6 bpm, p < 0.001), SkBF (−27.7 ± 13.9%, p = 0.002), TC (+2.6 ± 2.5, p = 0.024), and TS (−4.7 ± 2.5, p = 0.011) improved in COOL compared to CON. Reductions in T‾sk and Tneck were quickly lost (5 min) during the second exercise bout but Tdeep-head, Thead, and TS remained lower in COOL until the commencement of the second TT. Compared to CON, Tre (−0.2 ± 0.2 °C, p = 0.002) and RPE (−1.3 ± 0.9, p = 0.010) were lower in COOL during the second exercise bout. The reduction in mean power output at the second TT was attenuated in COOL (−13.9 ± 26.9 W) compared to CON (−29.3 ± 29.4 W; p = 0.015). In conclusion, the mixed-method cooling during a short break reduced physiological and perceptual strain and improved cycling TT performance.

Effects of Bilateral Dorsolateral Prefrontal Cortex High-Definition Transcranial Direct-Current Stimulation on Physiological and Performance Responses at Severe-Intensity Exercise Domain in Elite Road Cyclists.

To investigate the effects of bilateral dorsolateral prefrontal cortex high-definition transcranial direct-current stimulation (HD-tDCS) on physiological and performance responses during exercise at the upper limit of the severe-intensity exercise domain in elite-level road cyclists. Eleven elite-level road cyclists (VO2peak: 71.8 [3.1]mL·kg-1·min-1) underwent the HD-tDCS or SHAM condition in a double-blind, counterbalanced, and randomized order. After 20minutes of receiving either HD-tDCS on dorsolateral prefrontal cortex (F3 and F4) or SHAM stimulation, participants completed a 10-minute constant-load trial (CLT1) at 90% of the first ventilatory threshold and a 2-minute CLT (CLT2) at peak power output. Thereafter, they performed a simulated 2-km time trial (TT). Maximal oxygen uptake, respiratory exchange ratio, heart rate, and rating of perceived exertion were recorded during CLT1 and CLT2, whereas performance parameters were recorded during the TT. In 6 out of 11 cyclists, the total time to complete the TT was 3.0% faster in HD-tDCS compared to SHAM. Physiological and perceptual variables measured during CLT1 and CLT2 did not change between HD-tDCS and SHAM. HD-tDCS over the dorsolateral prefrontal cortex seemed to improve cycling TT performance within the upper limit of the severe-intensity exercise domain, suggesting that an upregulation of the prefrontal cortex could be critical even in this exercise intensity domain. However, the limited dimension and the high interindividual variability require further studies to test these putative ergogenic effects.

Effect of Acetaminophen on Endurance Cycling Performance in Trained Triathletes in Hot and Humid Conditions.

The effect of acetaminophen (ACT, also known as paracetamol) on endurance performance in hot and humid conditions has been shown previously in recreationally active populations. The aim of this study was to determine the effect of ACT on physiological and perceptual variables during steady-state and time-trial cycling performance of trained triathletes in hot and humid conditions. In a randomized, double-blind crossover design, 11 triathletes completed ∼60minutes steady-state cycling at 63% peak power output followed by a time trial (7kJ·kg body mass-1, ∼30min) in hot and humid conditions (∼30°C, ∼69% relative humidity) 60minutes after consuming either 20mg·kg body mass-1 ACT or a color-matched placebo. Time-trial completion time, gastrointestinal temperature, skin temperature, thermal sensation, thermal comfort, rating of perceived exertion, and fluid balance were recorded throughout each session. There was no difference in performance in the ACT trial compared with placebo (P = .086, d = 0.57), nor were there differences in gastrointestinal and skin temperature, thermal sensation and comfort, or fluid balance between trials. In conclusion, there was no effect of ACT (20mg·kg body mass-1) ingestion on physiology, perception, and performance of trained triathletes in hot and humid conditions, and existing precooling and percooling strategies appear to be more appropriate for endurance cycling performance in the heat.

Caffeine ingestion increases endurance performance of trained male cyclists when riding against a virtual opponent without altering muscle fatigue.

Caffeine improves cycling time trial (TT) performance; however, it is unknown whether caffeine is ergogenic when competing against other riders. The aim of this study was to investigate whether caffeine improves performance during a 4-km cycling TT when riding against a virtual opponent, and whether it is associated with increased muscle activation and at the expense of greater end-exercise central and peripheral fatigue. Using a randomized, crossover, and double-blind design, eleven well-trained cyclists completed a 4-km cycling TT alone without supplementation (CON), or against a virtual opponent after ingestion of placebo (OP-PLA) or caffeine (5mg.kg-1, OP-CAF). Central and peripheral fatigue were quantified via the pre- to post-exercise decrease in voluntary activation and potentiated twitch force, respectively. Muscle activation was continually measured during the trial via electromyography activity. Compared to CON, OP-PLA improved 4-km cycling TT performance (P = 0.018), and OP-CAF further improved performance when compared to OP-PLA (P = 0.050). Muscle activation was higher in OP-PLA and OP-CAF than in CON throughout the trial (P = 0.003). The pre- to post-exercise reductions in voluntary activation and potentiated twitch force were, however, similar between experimental conditions (P > 0.05). Compared to CON, OP-PLA increased the rating of perceived exertion during the first 2km, but caffeine blunted this increase with no difference between the OP-CAF and CON conditions. Caffeine is ergogenic when riding against a virtual opponent, but this is not due to greater muscle activation or at the expense of greater end-exercise central or peripheral fatigue.

Hydration, Ad Libitum Consumption, and Performance are Similar Between a Milk Permeate Solution, a Traditional Sports Drink, and Water Following Overnight Fluid Restriction in Recreationally Active Adults

Body water volume is tightly regulated such that the daily variation in total body water content is less than 1%. Imbalances in fluid volume can occur when fluid is not freely available, and can lead to decrements in physical performance when water losses exceed 2% body mass. Thus, it is essential to assess strategies that promote fluid replacement and retention during and following exercise. Beverages containing milk permeate have been suggested to be an efficacious alternative to traditional sports drinks for restoring hydration and maintaining performance. However, no prior studies have examined how consumption of such a beverage following overnight fluid restriction affects exercise performance in recreationally active individuals, or how ad libitum (AD) consumption following exercise affects indices of hydration, compared to other beverages.PURPOSEWe aimed to (1) determine how overnight fluid restriction and next‐day prescribed rehydration with either water (WAT), GatoradeÔ (GAT), or a milk permeate solution – GoodSportÒ (GS) – affects cycling time trial (TT) performance, and (2) compare the impact of ad libitum consumption of these three beverages on restoration of fluid balance and biomarkers of hydration status post‐TT.HYPOTHESESWe hypothesized that (1) time‐trial performance would be similarly improved following consumption of GAT and GS compared to WAT, and 2) ad libitum fluid consumption post‐time‐trial would be greater for GAT and GS compared to WAT.METHODSFour (3M/1F) recreationally active (&gt;150min/wk) young adults (25±1yr) completed 3 experimental visits consisting of a 15‐hr overnight fluid restriction prior to arrival at the laboratory for exercise trials. Subjects cycled at a moderate intensity (50% VO2max, 60 RPM) for one hour in a warm environment (30°C, 20% relative humidity) while consuming 2 mL/kg of randomly assigned fluid every 10 minutes, followed by a 5‐km TT. Following the TT, subjects cycled for one hour at 25% VO2max and were instructed to drink the randomly assigned fluid ad libitum.RESULTSTT performance, measured as both time and watts per kilogram (W/kg), was not different among trials (WAT: 562±36 sec, 2.2±0.4 W/kg; GAT: 570±58 sec, 2.3 ± 0.5 W/kg; GS 575±29 sec, 2.1 ± 0.6 W/kg; all p&gt;0.21). AD consumption was not different among trials (WAT: 1148±638 mL; GAT: 1200±355 mL; GS: 1271±486 mL). There were no differences in percent change in plasma volume (%ΔPV) at any time point among beverage conditions (all p&gt;0.28).CONCLUSIONTT performance, measured as both time and W/kg, was not improved following prescribed consumption of a milk permeate solution (GS) or a traditional sports drink (GAT) compared to WAT. AD fluid consumption was not different among beverage conditions during the one‐hour recovery cycling period after the TT. Changes in plasma volume, an important indicator of hydration, was not different among drink conditions at any time‐point, indicating subjects were similarly hydrated among beverage conditions.

Association of Heart Rate Variability and Simulated Cycling Time Trial Performance

The aim of this study was to determine if an abnormal HRV status would have negative effects on simulated individual time trial (ITT) performance in recreational cyclists. Recreational male (n=23, 42.8±8.3 years, 78.0±11.0 kg) and female (n=2, 37.0±6.8 years, 68.0±4.4 kg) cyclists completed simulated indoor 40-minute ITTs (40TT) over ten weeks. Participants were asked to complete simulated 40TTs under two HRV conditions: HRV normal values and HRV abnormal values. Participants recorded daily morning HRV readings to determine HRV status. Each participant performed all 40TTs on their personal indoor bike trainer and bike without external race simulation (e.g., Zwift). All cycling performance data were recorded on personal bike computers and submitted via a Qualtrics survey. A total of 138 ITTs (Normal = 75; Abnormal = 63) were assessed for relationships between HRV status and performance outcomes using a linear mixed-effects model with Cohen’s D for effect sizes (ES). A significant main effect of HRV status was found for peak power (F = 6.61; Normal: 372 ± 121.5 watts; Abnormal: 349 ± 105.9 watts; 380; p = 0.01; ES = 0.20) and peak speed (F = 6.12; Normal = 10.8 ± 1.2 m/s; Abnormal: 10.4 ± 1.2 m/s; p = 0.02; ES = 0.33). No significant main effect or effect sizes exceeding 0.20 were observed for all other performance variables. Daily HRV monitoring provides valuable insight that an individual’s peak power and speed may be compromised during cycling performance despite no changes in physiological or psychological indicators of effort. Coaches and cyclists can use morning HRV to inform race strategy ensuring desired performance outcomes, especially for those who rely on high power outputs

Effect of Clothing Fabric on 20-km Cycling Performance in Endurance Athletes.

Purpose: Examine the effect of synthetic fabrics (SYN, 60% polyester: 40% nylon) vs. 100% cotton fabric (CTN) on the 20-km cycling time trial (20 kmCTT) performance of competitive cyclists and triathletes.Methods: In this randomized controlled crossover study, 15 adults (5 women) aged 29.6 ± 2.7 years (mean ± SE) with a peak rate of O2 consumption of 60.0 ± 2.0 ml/kg/min completed a 20 kmCTT under ambient laboratory conditions (24.3 ± 0.7°C and 17 ± 7% relative humidity) with a simulated wind of ~3 m/s while wearing SYN or CTN clothing ensembles. Both ensembles were of snowflake mesh bi-layer construction and consisted of a loose-fitting long-sleeved shirt with full-length trousers.Results: Participants maintained a significantly (p < 0.05) higher cycling speed and power output over the last 6-km of the 20 kmCTT while wearing the SYN vs. CTN ensemble (e.g., by 0.98 km/h and 18.4 watts at the 20-km mark). Consequently, 20 kmCTT duration was significantly reduced by 15.7 ± 6.8 sec or 0.8 ± 0.3% during SYN vs. CTN trials (p < 0.05). Improved 20 kmCTT performance with SYN vs. CTN clothing could not be explained by concurrent differences in esophageal temperature, sweat rate, ratings of perceived exertion and/or cardiometabolic responses to exercise. However, it was accompanied by significantly lower mean skin temperatures (~1°C) and more favorable ratings of perceived clothing comfort and thermal sensation during exercise.Conclusion: Under the experimental conditions of the current study, athletic clothing made of synthetic fabrics significantly improved the 20 kmCTT performance of endurance-trained athletes by optimizing selected thermoregulatory and perceptual responses to exercise.

Effect of different pacing strategies on 4-km cycling time trial performance.

In cycling, there is a body of evidence that supports that an all-out start strategy is superior to an even-pacing strategy, but it is unknown whether an all-out start strategy is superior to a self-paced strategy. In the present study, we investigated the effects of three different pacing strategies on 4-km cycling time trial performance. After preliminary trials (familiarization trials and a baseline 4-km cycling time trial), in a randomized and counterbalanced order, twelve male cyclists (32.3±7.2 years old, maximum rate of O2 uptake (V̇O2peak) 4.3±0.4 L/min) completed: 1) a self-paced 4-km cycling time trial; 2) an all-out start (∼10 s), followed by maintenance of the average baseline trial power for the first km and self-paced cycling for the remaining trial (all-out+mean); and 3) an all-out start (∼10 s), followed by a power 5% above the average baseline trial power for the first km and self-paced cycling for the remaining trial (all-out+5%mean). Although there was a significant interaction between power and distance (P=0.001) with different power distribution profiles throughout the trial, there was no significant difference (P=0.99) between the three strategies for overall exercise performance (self-paced 379.8±13.9 s, all-out+mean 380.0±16.0 s, and all-out+5%mean 380.2±11.5 s). Oxygen uptake, rating of perceived effort, and heart rate were also similar across the pacing strategies. Different all-out start strategies did not confer additional benefits to performance compared to a self-paced strategy.

A Novel Approach of Modelling and Predicting Track Cycling Sprint Performance

In cycling, performance models are used to investigate factors that determine performance and to optimise competition results. We present an innovative and easily applicable mathematical model describing time-resolved approaches for both the physical aspects of tractional resistance and the physiological side of propelling force generated by muscular activity and test its validity to reproduce and forecast time trials in track cycling. Six elite track cyclists completed a special preparation and two sprint time trials in an official velodrome under continuous measurement of crank force and cadence. Fatigue-free force-velocity profiles were calculated, and their fatigue-induced changes were determined by non-linear regression analysis using a monoexponential equation at a constant slope. Model parameters were calibrated based on pre-exercise performance testing and the first of the two time-trials and then used to predict the performance of the second sprint. Measured values for power output and cycling velocity were compared to the modelled data. The modelled results were highly correlated to the measured values (R2&gt;0.99) without any difference between runs (p&gt;0.05; d&lt;0.1). Our mathematical model can accurately describe sprint track cycling time trial performance. It is simple enough to be used in practice yet sufficiently accurate to predict highly dynamic maximal sprint performances. It can be employed for the evaluation of completed runs, to forecast expected results with different setups, and to study various contributing factors and quantify their effect on sprint cycling performance.

The Effect of Isolated and Combined Application of Menthol and Carbohydrate Mouth Rinses on 40 km Time Trial Performance, Physiological and Perceptual Measures in the Heat.

The current study compared mouth swills containing carbohydrate (CHO), menthol (MEN) or a combination (BOTH) on 40 km cycling time trial (TT) performance in the heat (32 °C, 40% humidity, 1000 W radiant load) and investigates associated physiological (rectal temperature (Trec), heart rate (HR)) and subjective measures (thermal comfort (TC), thermal sensation (TS), thirst, oral cooling (OC) and RPE (legs and lungs)). Eight recreationally trained male cyclists (32 ± 9 y; height: 180.9 ± 7.0 cm; weight: 76.3 ± 10.4 kg) completed familiarisation and three experimental trials, swilling either MEN, CHO or BOTH at 10 km intervals (5, 15, 25, 35 km). The 40 km TT performance did not differ significantly between conditions (F2,14 = 0.343; p = 0.715; η2 = 0.047), yet post-hoc testing indicated small differences between MEN and CHO (d = 0.225) and MEN and BOTH (d = 0.275). Subjective measures (TC, TS, RPE) were significantly affected by distance but showed no significant differences between solutions. Within-subject analysis found significant interactions between solution and location upon OC intensity (F28,196 = 2.577; p < 0.001; η2 = 0.269). While solutions containing MEN resulted in a greater sensation of OC, solutions containing CHO experienced small improvements in TT performance. Stimulation of central CHO pathways during self-paced cycling TT in the heat may be of more importance to performance than perceptual cooling interventions. However, no detrimental effects are seen when interventions are combined.

The effects of sodium bicarbonate supplementation at individual time-to-peak blood bicarbonate on 4-km cycling time trial performance in the heat

ABSTRACT The purpose of this study was to explore the effect of individualised sodium bicarbonate (NaHCO3) supplementation according to a pre-established individual time-to-peak (TTP) blood bicarbonate (HCO3 −) on 4-km cycling time trial (TT) performance in the heat. Eleven recreationally trained male cyclists (age: 28 ± 6 years, height: 180 ± 6 cm, body mass: 80.5 ± 8.4 kg) volunteered for this study in a randomised, crossover, triple-blind, placebo-controlled design. An initial visit was conducted to determine TTP HCO3 − following 0.2 g.kg−1 body mass (BM) NaHCO3 ingestion. Subsequently, on three separate occasions, participants completed a 4-km cycling TT in the heat (30 degrees centigrade; °C) (relative humidity ∼40%) following ingestion of either NaHCO3 (0.2 g.kg−1 body mass), a sodium chloride placebo (0.2 g.kg−1 BM; PLA) at the predetermined individual TTP HCO3 −, or no supplementation (control; CON) . Absolute peak [HCO3 −] prior to the 4-km cycling TT's was elevated for NaHCO3 compared to PLA (+2.8 mmol.l−1; p = 0.002; g = 2.2) and CON (+2.5 mmol.l−1; p < 0.001; g = 2.1). Completion time following NaHCO3 was 5.6 ± 3.2 s faster than PLA (1.6%; CI: 2.8, 8.3; p = 0.001; g = 0.2) and 4.7 ± 2.8 s faster than CON (1.3%; CI: 2.3, 7.1; p = 0.001; g = 0.2). These results demonstrate that NaHCO3 ingestion at a pre-established individual TTP HCO3 − improves 4-km cycling TT performance in the heat, likely through enhancing buffering capacity. Highlights This is the first time NaHCO3 ingestion has been shown to improve 4-km cycling TT performance in conditions of high ambient heat. A smaller dose of NaHCO3 (0.2 g.kg−1 BM) is ergogenic in the heat, which is smaller than the dose typically ingested for sports performance (0.3 g.kg−1 BM). This is important, as gastrointestinal discomfort is typically lower as the dose reduces. This study suggests that the individualised time-to-peak HCO3 − ingestion strategy with lower doses of NaHCO3 is an ergogenic strategy in conditions of high ambient heat.

Effect of Iso–Caloric Sago and Soy Supplementations during 90 Minutes Steady–State Cycling on Subsequent 20–km Cycling Time Trial Performance in the Heat

Effect of Iso–Caloric Sago and Soy Supplementations during 90 Minutes Steady–State Cycling on Subsequent 20–km Cycling Time Trial Performance in the Heat

Sex-Specific Effects of Respiratory Muscle Endurance Training on Cycling Time Trial Performance in Normoxia and Hypoxia.

Objectives: We tested the hypotheses that respiratory muscle endurance training (RMET) improves endurance cycling performance differently in women and men and more so in hypoxia than in normoxia.Design: A prospective pre–post cross-over study with two testing conditions.Methods: Healthy and active women (seven, 24 ± 4 years, mean ± standard deviation [SD]) and men (seven, 27 ± 5 years) performed incremental cycling to determine maximum oxygen consumption (VO2peak) and power output (Wpeak) and on different days two 10-km cycling time trials (TTs) in normoxia and normobaric hypoxia (FiO2, 0.135, ~3,500 m equivalent), in a balanced randomized order. Next they performed supervised RMET in normoxia (4 weeks, 5 days/week, 30 min/day eucapnic hyperpnea at ~60% predicted maximum voluntary ventilation) followed by identical post-tests. During TTs, heart rate, ear oximetry reading, and Wpeak were recorded.Results: The VO2peak and Wpeak values were unchanged after RMET. The TT was improved by 7 ± 6% (p < 0.001) in normoxia and 16 ± 6% (p < 0.001) in hypoxia. The difference between normoxic and hypoxic TT was smaller after RMET as compared with that before RMET (14% vs. 21%, respectively, p < 0.001). All effects were greater in women (p < 0.001). The RMET did not change the heart rate or ear oximetry reading during TTs.Conclusion: We found a greater effect of RMET on cycling TT performance in women than in men, an effect more pronounced in hypoxia. These findings are congruent with the contention of a more pronounced performance-limiting role of the respiratory system during endurance exercise in hypoxia compared with normoxia and more so in women whose respiratory system is undersized compared with that of men.

The Effect of Crank Arm Length on Cycling Economy and Performance in Triathlon

Given the nature of a triathlon race, the cycling distance is typically much longer than swimming and running across race distances from sprint to Ironman. Besides, triathletes should try to not only maintain a certain level of cycling power but also consider cycling economy to make a better performance in both the cycling portion and the overall race (Bonacci et al., 2013; Sleivert &amp; Rowland, 1996; Swinnen et al., 2018). The cycling economy is an important indicator to predict cycling performance in terms of time to complete a certain distance. Both cycling economy and performance are determined by the interaction between mechanical output and physiological input (Barratt et al., 2016; Korff et al., 2007; Sunde et al., 2010). Theoretically, improving cycling economy elicits a better cycling time trial performance and/or less physiological demands (e.g., rate of oxygen consumption: V̇O2, heart rate) to complete at a given distance. The crank arm length (CAL) is one of the important factors among many variables that affect the economy and performance in cycling (McDaniel et al., 2002). Therefore, the appropriate selection of CAL may play a key role in improving the cycling portion of the race and entire triathlon performance. The purpose of this review is to identify the effects of acute changing CAL on physiological and biomechanical responses during cycling.

Effects of Transcranial Direct Current Stimulation on Cycling Time Trial Performance and Prefrontal Cortex Activation

Background: Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low levels of a constant current via scalp electrodes to specifically targeted areas of the brain. The effects of tDCS on whole-body exercise performance has been of interest in recent literature. The purpose of the current investigation was to investigate if tDCS, administered via Halo Sport, influences time trial performance in trained cyclists, and if changes in exercise performance are associated with prefrontal cortex (PFC) activation and/or muscle oxygenation (SmO2). Methods: Twelve recreationally trained cyclists volunteered to participate in a crossover study design involving two 10-kilometer time trials following 20 min of tDCS or a sham condition. Results: t-tests showed there was no significant difference in performance (time to completion) or physiological measures (blood lactate (BL) concentration, heart rate (HR), SmO2, PFC oxygenation) between the Halo and sham conditions. Conclusions: These results indicate that the application of tDCS via Halo Sport does not induce changes in exercise performance or related physiological parameters during a 10-kilometer cycling time trial.

Effects of prior high-intensity endurance exercise in subsequent 4-km cycling time trial performance and fatigue development

To investigate the effects of prior high-intensity endurance exercise on time trial (TT) performance and fatigue responses. Eleven male cyclists visited the lab in two separate visits. The first visit was composed by a maximal cycling incremental test (MIT) followed by 15 min of passive rest before a 4-km cycling TT. The second visit (control, CON) was composed by moderate-intensity exercise for 5 min before the TT. Fatigue of knee extensors was assessed by isometric maximal voluntary contractions (IMVC), while the central (voluntary activation [VA]) and peripheral fatigue (peak torque of potentiated twitches [TwPt]) were evaluated using electrically-evoked contractions performed before and 1 min after the TT. Power output (PO), oxygen uptake (V̇O 2 ) and rating of perceived exertion (RPE) were recorded throughout the TT. TT performance (+2.6%) and average PO (+5.7%) improved in MIT compared to CON condition. While peripheral fatigue level was greater in MIT condition ( P < 0.05), the central fatigue was lower compared to CON condition ( P < 0.05). There were greater overall V̇O 2 values (3.9 ± 0.4 vs 3.6 ± 0.4 L·min −1 ) but similar RPE responses (15 ± 2 vs 15 ± 3 a.u.) in MIT compared to CON. These findings indicate that prior high-intensity endurance exercise has positive effects in subsequent TT performance compare to moderate-intensity warm-up, despite exacerbated peripheral fatigue development. This response might be driven by greater aerobic reliance and exertion tolerance. Étudier les effets d’un pré exercice d’endurance à haute intensité sur la performance chronométrique (PC) et la fatigue. Onze cyclistes masculins sont venus à deux reprises au laboratoire. La première session était composée d’un test triangulaire maximal (TTM) suivi de 15 min de récupération passive avant la PC de 4 km à vélo. La seconde session était d’un exercice d’intensité modérée pendant 5 mis avant la PC (la condition contrôle, CON). La fatigue des extenseurs du genou était évaluée avec des contractions volontaires maximales isométriques (CVMI), dans un même temps la fatigue centrale [activation volontaire (AC)] et périphérique [pic de force des potentiels des twitches (PfPT)] était évaluée en utilisant l’électrostimulation avant et 1 min après la PC. La consommation d’oxygène (V̇O 2 ) et évaluation de l’effort perçu (RPE) était mesurée pendant toute la durée de la PC. La PC (+2,6 %) et la PO moyenne (+5,7 %) se sont améliorées dans le MIT par rapport à la condition CON. Alors que le niveau de fatigue périphérique était plus élevé en condition MIT ( p < 0,05), la fatigue centrale était plus faible par rapport à la condition CON ( p < 0,05). Il y avait des valeurs de V̇O2 plus élevées (3,9 ± 0,4 vs 3,6 ± 0,4 L·min −1 ) mais des réponses RPE similaires (15 ± 2 vs 15 ± 3 ua) dans le TTM par rapport à CON. Ces résultats indiquent que les exercices d’endurance de haute intensité antérieure ont des effets positifs sur la PC subséquent par rapport à un échauffement d’intensité modérée, malgré un développement de fatigue périphérique exacerbé. Cette réponse pourrait être motivée par une plus grande dépendance aérobie et tolérance à l’effort.

Beta-alanine did not improve high-intensity performance throughout simulated road cycling

ABSTRACT This study investigated the effect of beta-alanine supplementation on short-duration sprints and final 4-km simulated uphill cycling time-trial performance during a comprehensive and novel exercise protocol representative of the demands of road-race cycling, and determined if changes were related to increases in muscle carnosine content. Seventeen cyclists (age 38 ± 9 y, height 1.76 ± 0.07 m, body mass 71.4 ± 8.8 kg, V̇O2max 52.4 ± 8.3 ml·kg−1·min−1) participated in this placebo-controlled, double-blind study. Cyclists undertook a prolonged intermittent cycling protocol lasting 125 min, with a 10-s sprint every 20 min, finishing with a 4-km time-trial at 5% simulated incline. Participants completed two familiarization sessions, and two main sessions, one pre-supplementation and one post-supplementation following 28 days of 6.4 g·day−1 of beta-alanine (N=11) or placebo (N=6; maltodextrin). Muscle biopsies obtained pre- and post-supplementation were analysed for muscle carnosine content. There were no main effects on sprint performance throughout the intermittent cycling test (all P>0.05). There was no group (P=0.69), time (P=0.50) or group x time interaction (P=0.26) on time-to-complete the 4-km time-trial. Time-to-completion did not change from pre- to post-supplementation for BA (−19.2 ± 45.6 s, P=0.43) or PL (+2.8 ± 31.6 s, P=0.99). Beta-alanine supplementation increased muscle carnosine content from pre- to post-supplementation (+9.4 ± 4.0 mmol·kg−1dm; P<0.0001) but was not related to performance changes (r=0.320, P=0.37). Chronic beta-alanine supplementation increased muscle carnosine content but did not improve short-duration sprint performance throughout simulated road race cycling, nor 4-km uphill time-trial performance conducted at the end of this cycling test. Highlights Performance during prolonged cycling events often depends on the ability to maintain an increased power output during higher intensity periods. Thus, cyclists are likely heavily dependent on their ability to resist fatigue during these periods of high-intensity activity. Meta-analytical data show beta-alanine to be an effective supplement to improve exercise outcomes, but little work exists on its efficacy during dynamic actions that are common during prolonged cycling. Beta-alanine supplementation increased muscle carnosine content but did not generate improvements in the performance of high-intensity cycling (10-s sprints or 4-km uphill time-trial) during a simulated road race cycling protocol. These data suggest that short duration sprints (≤10 s) and longer duration (>10 min) high-intensity activity throughout endurance cycling may not be improved with beta-alanine supplementation despite increases in muscle carnosine content.