Velotron Cycle Ergometer Research Articles

Exercise Task Characteristics Influence Time Perception During Vigorous Exercise

Abstract The passage of time is observed subjectively, and changes rate based on attentional or physiological stimuli. Self-adjusted exercise typically leads to the experience that time is progressing more slowly than it really is, but only when intensity is sufficiently high. This study was designed to determine if high exercise intensity at a fixed work rate would lead to differences in subjective timing. Subjects (26 total; 17 men/ 9 women) completed a maximal exercise test on a Velotron cycle ergometer until volitional exhaustion. A time production task was completed at baseline prior to exercise, and during each 3-min stage. Heart rate (HR) was assessed continuously. Time perception ratio (actual time divided by perceived time) was compared at baseline, during light exercise (40 W), and during the first stage at which age-predicted HRmax was considered vigorous (76–90% HRmax), using a repeated-measures analysis of variance (ANOVA). The result of the ANOVA was significant, F1.63,39 = 6.19, p = 0.007, η2 = 0.21. Bonferroni-adjusted post-hoc comparisons showed that the time perception ratio was higher during vigorous exercise (1.21 ± 0.34) compared to baseline (1.06 ± 0.19; p = 0.028) and light (1.09 ± 0.27; p = 0.048) exercise. Unlike several similar studies finding that subjective time increases at higher exercise intensities, the results of this study indicate the opposite effect at a fixed vigorous-intensity work rate. The motivational nature of the task and unique attentional factors associated with it are likely explanations for the deviation from earlier reports.

The Effect of Caffeine and 1976T>C (ADORA2A) Genetic Variants on Anaerobic Performance during a 30‐Second Wingate Test

INTRODUCTIONThe supplementation of caffeine is often used to elicit an enhancement of focus, arousal, or performance; however, intra‐individual response to caffeine has been shown to vary the effects of caffeine. Genetic variation of the adenosine receptor, 1976T>C (ADORA2A), has been linked to caffeine sensitivity and is a potential target for understanding individual differences. The TT genotype demonstrates an increased sensitivity to caffeine compared to the TC/CC genotype. The anxiogenic effects, genetic influences, and pharmacological interactions play a role in the ergogenic effects of caffeine.PURPOSETo examine the effects of caffeine and ADORA2A genetic variants on anaerobic performance during a 30s Wingate test.METHODSSixteen trained subjects (age=19.8±0.5 years, weight=70.5±10.3 kg, height=175.8±8.8 cm) volunteered for a randomized, counterbalanced, and double‐blind study. Sixty minutes prior to testing, the subjects ingested a gelatin capsule containing either caffeine (CAF), 5mg·kg−1 bodyweight (BW), or a proportional placebo (PLA) of maltodextrin. The 30‐second Wingate Test (WAnT30) trials were performed on a Velotron cycle ergometer at 0.075 kg·BW−1 resistance and were separated by a minimum of 48 hours. Anaerobic power (AP) (W·kg−1), anaerobic capacity (AC) (W·kg−1), and total power (TP) (W) were determined for each condition. Genotype was determined using a mouth rinse of 0.9% NaCl to obtain buccal epithelial cells, which were lysed using proteinase k. DNA was extracted using QiAmp Mini spin columns. The allelic determination of ADORA2A was identified using TaqMan® SNP Assay (rs5751876) and 40 thermocycles for amplification with a One‐Step qPCR (Life Technologies, Carlsbad, CA). The data was analyzed using a 2 (condition) × 2 (genotype) ANOVA with repeated measures, p < 0.05.RESULTSGenotypic distribution resulted in 6 TT and 10 TC/CC individuals. The main effect of condition, PLA vs CAF, produced no significant ergogenic effect for AP (P=0.52), AC (p=0.67), or TP (p=0.85). The main effect of ADORA2A, TT vs TC/CC, produced no significant difference for AP (p=0.95), AC (p=0.49), or TP (p=0.95). The interaction effect of condition x genotype showed no significant differences for AP (p=0.65), AC (p=0.94), or TP (p=0.95). Although follow up simple effect tests showed no significant differences for AP, individuals with the TT genotype showed a 4.5% (11.2±1.12 to 11.7±1.3), PLA to CAF, improvement compared to the 0.81% (11.4±1.4 to 11.5±1.3) improvement of the TC/CC individuals. Likewise, for TP (W), TT individuals improved by 1.8% (192975±25911 to 196525±21111) while TC/CC individuals increased only 0.94% (194787±48699 to 196635±44092).CONCLUSIONCaffeine did not elicit a significant anaerobic ergogenic effect for the WAnt30. However, the results indicate that individuals with the TT genotype did experience larger percent improvement than their TC/CC counterparts. As such, future research should continue to investigate these inter‐individual differences by increasing sample size and identifying other genes that interact with caffeine.Support or Funding InformationMessiah College

Athlete-Opponent Interdependency Alters Pacing and Information-Seeking Behavior.

The influence of interdependency between competitors on pacing decision-making and information-seeking behavior has been explored. This has been done by only altering instructions, and thereby action possibilities, while controlling environment (i.e., competitor behavior) and exercise task. Twelve participants performed a 4-km time trial on a Velotron cycle ergometer in a randomized, counterbalanced order alone with no virtual opponent (NO), against a virtual opponent with no restrictions (low athlete-opponent interdependency [OP-IND]), or against a virtual opponent who the participant was permitted to overtake only once during the trial (high athlete-opponent interdependency [OP-DEP]). Information-seeking behavior was evaluated using an SMI eye tracker. Differences in pacing, performance, and information-seeking behavior were examined using repeated-measures ANOVA (P < 0.05). Neither mean power output (NO, 298 ± 35 W; OP-IND, 297 ± 38 W; OP-DEP, 296 ± 37 W) nor finishing time (NO, 377.7 ± 17.4 s; OP-IND, 379.3 ± 19.5 s; OP-DEP, 378.5 ± 17.7 s) differed between experimental conditions. However, power output was lower in the first kilometer of OP-DEP compared with the other experimental conditions (NO, 332 ± 59 W; OP-IND, 325 ± 62 W; OP-DEP, 316 ± 58 W; both P < 0.05), and participants decided to wait longer before they overtook their opponent (OP-IND, 137 ± 130 s; OP-DEP, 255 ± 107 s; P = 0.040). Moreover, total fixation time spent on the avatar of the virtual opponent increased when participants were only allowed to overtake once (OP-IND, 23.3 ± 16.6 s; OP-DEP, 55.8 ± 32.7 s; P = 0.002). A higher interdependency between athlete and opponent altered pacing behavior in terms of in-race adaptations based on opponent's behavior, and it induced an increased attentional focus on the virtual opponent. Thus, in the context of exercise regulation, attentional cues are likely to be used in an adaptive way according to their availability and situational relevance, consistent with a decision-making framework based on the interdependence of perception and action.

Test-retest reliability and validity of the Stages mountain bike power meter

BACKGROUND: Stages device is an affordable power meter used by several professional and competitive cyclists. However, few studies have investigated its validity and reliability. OBJECTIVE: The aim of this study was to analyze the validity and the reliability of the Stages mountain biking power met er. METHODS: Twenty-six cyclists (age: 35 ± 7 years, VO2max: 58 ± 7 ml⋅kg-1⋅min-1) completed six testing sessions within a 4-week period. Cyclists performed an incremental exercise test, a 5-min time trial (TT), and a 20-min TT in different days using the Velotron cycle ergometer attached with the power meter. RESULTS: The power output of the Stages was significantly lower during each step of the incremental exercise test (11.8 to 16.4%) and performance testing (∼ 18%) compared with the cycle ergometer. Bland Altman plots presented high bias and limits of agreements when comparing the power output of the Stages and Velotron. In general, high coefficient of variation was found for the power and cadence of the Velotron and Stages, except for the Velotron’s power during the 20-min TT. CONCLUSIONS: The interchangeable use of the power from the Velotron and Stages is not recommended due to the observed high within-subject variation.

Effects Of Cycling In The Cold On Neuromuscular Activation And Fatigue

PURPOSE: To examine the effects of cold exposure on neuromuscular activation and fatigue during aerobic cycling exercise. METHODS: Five apparently healthy males (24.8 + 2.9 years; 183.1 + 2.2cm; 80.5 + 4.4kg; 11.3 + 2.8%BF; 3.97 + 0.34 L[BULLET OPERATOR]min-1) visited the laboratory on three separate occasions. During the first visit, participants performed a VO2max test on a Velotron cycle ergometer. During the two remaining trials, participants performed two, five-second maximal isometric voluntary contractions (MVICs) of the right leg extensors prior to entering the environmental chamber. In the environmental chamber, volunteers cycled for 60 min at 60% of their VO2max in either a low- (5°C / 45%RH; LT), or moderate-temperature (22°C / 45%; MT), in counterbalanced fashion. Electromyography (EMG) of the vastus lateralis was recorded during the 60-minute exercise protocol during the first two minutes, and during the last two minutes of every 10-minute period (0-2min, 8-10min, 18-20min, 28-30min, 38-40min, 48- 50min, 58-60min). Root mean square (RMS), mean power frequency (MPF) and median power frequency (MEDPF) were then normalized to the MVIC for each time point. Data were analyzed using a within subjects repeated measures ANOVA. RESULTS: No significant differences were observed between conditions (LT and MT) for RMS (F = ; p = 0.591) MPF (F = 0.003; p = 0.959), or MEDPF (F = 1.438; p=0.297). A significant main effect of time was observed for RMS F = 8.187, p<0.001). Specifically, RMS at 8-10Min (26.369 + 3.542%), 18-20Min (24.782 + 3.572%), 38-40Min (25.722 + 3.534%) and 48-50Min (26.070 + 3.451%) were significantly lower than RMS at 58-60Min (27.091 + 3.521%). There was also a significant effect of time for MPF (F = 3.049; p = .023), with a significantly higher MPF at 18-20min (85.694 + 1.467%) and 38-40min (85.942 + 1.408%) compared to 8-10min (83.165 + 1.215%). CONCLUSION: The increase in RMS observed at the end of exercise suggests an increase in neural drive and motor unit activity, suggestive of an increase in motor unit recruitment and fatigue during aerobic cycling exercise at 60% VO2max. Furthermore, MPF significantly increased from the beginning of exercise, suggesting an increase in action potential conduction velocity.

Effects of Aerobic Cycling Exercise in the Heat on Neuromuscular Activation and Fatigue

PURPOSE: To examine the effects of heat on neuromuscular activation and fatigue during aerobic cycling exercise. METHODS: Five recreationally active men (24.8 + 2.9 years; 183.1 + 2.2cm; 80.5 + 4.4kg; 11.3 + 2.8%BF; 3.97 + 0.34 L[BULLET OPERATOR]min-1) visited the laboratory on three separate occasions. Participants completed a VO max test on a Velotron cycle ergometer and underwent skinfold assessment. The remaining two visits consisted of cycling for 60 min at 60% of their previously determined VO2max in either a high- temperature (35°C / 45%RH) (HT), or a moderate-temperature (22°C / 45%) (MT) in a counterbalanced fashion. Electromyography (EMG) of the vastus lateralis of the right leg was recorded during the 60-min exercise protocol during the first two min, and during the last two min of every 10-min period (0-2 min, 8-10 min, 18-20 min, 28-30 min, 38-40 min, 48-50 min, 58-60 min). Raw EMG recordings were normalized to maximal voluntary isometric contractions (MVICs), and analyzed for root mean square (RMS), mean power frequency (MPF) and median power frequency (MEDPF). Data were analyzed using a within-subjects repeated measures ANOVA. RESULTS: No significant interaction (F = 0.519; p = 0.788) or main effects (Time: F = 2.069; p = 0.095; Condition: F = 2.742; p = 0.173) were observed for RMS. Additionally, no interaction was observed for MPF (F = 1.310; p = 0.291), however, a significant main effect of condition was observed for MPF (F = 15.325; p = 0.017), with a significantly higher MPF in HT (91.27 + 3.03%) compared to MT (p = 0.017; 85.00 + 3.07%). A significant main effect of time was also observed for MPF (F = 3.282; p = 0.017), with a significantly higher MPF at 58-60 min (89.30 + 2.86%) compared to 8-10 min (p = 0.039; 86.34 + 2.34%). No significant interaction was observed for MEDPF (F = 1.214; p = 0.333), though a significant main effect of time was observed (F = 2.841; p = 0.031). Pairwise comparisons indicate this difference occurred between 0-2min (82.469 + 3.098%) and 28-30min (p = 0.023; 85.834 + 2.638%). CONCLUSION: Exercise in the heat resulted in a significantly higher MPF, with an increased MPF towards the end of exercise. These data suggest that heat exposure, as well as continuous aerobic exercise, may elicit an increase in action potential conduction velocity over the vastus lateralis.

Racing an Opponent: Alteration of Pacing, Performance, and Muscle-Force Decline but Not Rating of Perceived Exertion.

Performing against a virtual opponent has been shown to invite a change in pacing and improve time-trial (TT) performance. This study explored how this performance improvement is established by assessing changes in pacing, neuromuscular function, and perceived exertion. After a peak-power-output test and a familiarization TT, 12 trained cyclists completed two 4-km TTs in randomized order on a Velotron cycle ergometer. TT conditions were riding alone (NO) and riding against a virtual opponent (OP). Knee-extensor performance was quantified before and directly after the TT using maximal voluntary contraction force (MVC), voluntary activation (VA), and potentiated doublet-twitch force (PT). Differences between the experimental conditions were examined using repeated-measures ANOVAs. Linear-regression analyses were conducted to associate changes in pacing to changes in MVC, VA, and PT. OP was completed faster than NO (mean power output OP 289.6 ± 56.1 vs NO 272.2 ± 61.6W; P = .020), mainly due to a faster initial pace. This was accompanied by a greater decline in MVC (MVC pre vs post -17.5% ± 12.4% vs -11.4% ± 10.9%, P = .032) and PT (PT pre vs post -23.1% ± 14.0% vs -16.2% ±11.4%, P = .041) after OP than after NO. No difference between conditions was found for VA (VA pre vs post -4.9% ± 6.7% vs -3.4% ± 5.0%, P = .274). Rating of perceived exertion did not differ between OP and NO. The improved performance when racing against a virtual opponent was associated with a greater decline in voluntary and evoked muscle force than riding alone, without a change in perceived exertion, highlighting the importance of human-environment interactions in addition to one's internal state for pacing regulation and performance.

Kinematic Measures Of The Knee While Cycling

Factors contributing to knee pain in cyclists include deviations from optimal pedaling patterns and poor bike fit. Accurate measurement of kinematics is essential to obtain optimal positioning, but motion analysis equipment cost is an obstacle for many clinicians. PURPOSE: To compare the Retül 3D motion capture system to the Vicon 3D system. A lack of significant difference between devices would support a low-cost option for clinicians working with cyclists. METHODS: Cycling kinematics were captured from eleven competitive female cyclists using a 10-camera Vicon MX system and compared with a cycling-specific motion analysis system, Retül, while pedaling at 70% peak power output on a Velotron cycle ergometer. RESULTS: MANOVA demonstrated no significant difference between systems for knee range of motion (ROM) (mean difference (MD)=0.12°, p=0.96), knee extension (MD=0.12°, p=0.10), knee frontal plane knee angles (MD=2.7°, p=0.15), ankle dorsiflexion (DF) (MD=1.45°, p=0.46) and plantarflexion (PF) (MD=4.51°). However, knee flexion (MD=1.42°, p=0.02), hip flexion (MD=32.83°, p<0.001), hip ROM (MD=3.8°, p<0.001), ankle ROM (MD=3.7°, p<0.001) and measurement of the mean knee distance from bicycle centerline (MD=11.13 mm, p<0.001) were significantly different between systems. ICC indicated moderate agreement between systems for knee flexion (ICC(2,5)=0.52, p<0.001). Linear regression of difference scores on mean scores demonstrate a significant relationship for knee flexion, hip ROM and ankle DF (p=0.66, p=0.10, p=0.38, respectively). CONCLUSION: In general, these data support Retül for use in comparison with Vicon for the measurement of knee extension, ankle DF and ankle PF, which are most relevant measurements for obtaining correct fit on a bicycle. Keywords: Bike-fit, kinematics, agreement

Socially Prescribed Perfectionism Might Predict Enhanced Performance When Racing Against an Opponent

Recent research has shown that racing against an opponent can improve endurance exercise performance (Konings et al, 2016). To what extent athletes can be motivated by racing against an adversary might depend at least partially on personality characteristics such as type of perfectionism. PURPOSE: We sought to explore the relationship between self-oriented (SO) and socially prescribed perfectionism (SPP) (Hewitt & Flett, 1991) and time-trial performance. We hypothesized that SPP would be related to performance enhancements associated with the presence of an opponent, but that SO would not. METHODS: Twelve experienced cyclists (45.8 ± 7.0 years) completed four 4-km time trials (TT) on a VeloTron cycle ergometer. Participants performed three TTs without opponent (TT1no, TT2no, TT3no) and one TT against a virtual opponent (TTopp). Mean performance on the three trials without an opponent was calculated and the difference (ΔTTno-TTopp) between the resulting “meanTTno” and TTopp was assessed for each participant. Participants also answered the 12-item “perfectionism in sport scale” (PPS-P) (Hill et al., 2016) on a 6-point Likert scale before the first race. Spearman correlations of the participants’ mean scores on the PPS-P and ΔTTno-TTopp were calculated. RESULTS: Overall, there was no significant difference in performances over the 4 trials: T1 = 385.86 ±18.07s; T2 = 380.31 ± 20.75s; TTno = 377.66 ± 17.40s and TTopp 378.86 ± 19.68s. Mean score on PPS-P was 4.29 ± 0.96 for SO and 2.83 ± 0.91 for SPP. A significant positive correlation was found between SPP and ΔTTno-TTopp (ρ = 0.867, p < 0.01), but we found no relationship between SO and ΔTTno-TTopp. CONCLUSION: Previous studies have shown that being confronted with a (virtual) opponent enhances endurance athletes’ performance. In the present group of cyclists, overall 4-km performances with and without opponent did not differ significantly. Interestingly, our results show that the performance enhancing effect of a virtual opponent during a 4 km cycling trial is correlated to socially prescribed perfectionism in sport. These findings support current literature and our hypothesis that the positive effect of racing against an opponent might differ according to athletes’ psychological characteristics.

Validation of a new pedal sensor to measure torque, power and work during pedaling.

Validation of a new pedal sensor to measure torque, power and work during pedaling.

Single and Combined Effects of Beetroot Crystals and Sodium Bicarbonate on 4-km Cycling Time Trial Performance.

When ingested alone, beetroot juice and sodium bicarbonate are ergogenic for high-intensity exercise performance. This study sought to determine the independent and combined effects of these supplements. Eight endurance trained (VO2max 65 mL·kg·min-1) male cyclists completed four × 4-km time trials (TT) in a doubleblind Latin square design supplementing with beetroot crystals (BC) for 3 days (15 g·day-1 + 15 g 1 h before TT, containing 300 mg nitrate per 15 g), bicarbonate (Bi 0.3 g·kg-1 body mass [BM] in 5 doses every 15 min from 2.5 h before TT); BC+Bi or placebo (PLA). Subjects completed TTs on a Velotron cycle ergometer under standardized laboratory conditions. Plasma nitrite concentrations were significantly elevated only in the BC+Bi trial before the TT (1520 ± 786 nmol·L-1) compared with baseline (665 ± 535 nmol·L-1, p = .02) and the Bi and PLA conditions (Bi: 593 ± 203 nmol·L-1, p < .01; PLA: 543 ± 369 nmol·L-1, p < .01). Plasma nitrite concentrations were not elevated in the BC trial before the TT (1102 ± 218 nmol·L-1) compared with baseline (975 ± 607 nmol·L-1, p > .05). Blood bicarbonate concentrations were increased in the BC+Bi and Bi trials before the TT (BC+Bi: 30.9 ± 2.8 mmol·L-1; Bi: 31.7 ± 1.1 mmol·L-1). There were no differences in mean power output (386-394 W) or the time taken to complete the TT (335.8-338.1 s) between any conditions. Under the conditions of this study, supplementation was not ergogenic for 4-km TT performance.

The behavior of an opponent alters pacing decisions in 4-km cycling time trials

IntroductionThe present study aimed to explore how athletes respond to different behaviors of their opponents. MethodsTwelve moderately to highly physically active participants with at least two years of cycling experience completed four 4-km time trials on a Velotron cycle ergometer. After a familiarization time trial (FAM), participants performed three experimental time trials in randomized order with no opponent (NO), a virtual opponent who started slower and finished faster compared to FAM (OP-SLOWFAST), or a virtual opponent who started faster and finished slower compared to FAM (OP-FASTSLOW). Repeated-measures ANOVAs (P<0.05) were used to examine differences in pacing and performance related to power output, velocity and RPE. ResultsOP-SLOWFAST and OP-FASTSLOW were completed faster compared to NO (385.5±27.5, 385.0±28.6, and 390.6±29.3s, respectively). An interaction effect for condition×distance (F=3.944, P<0.001) indicated differences in pacing profiles between conditions. Post-hoc analysis revealed that a less aggressive starting strategy was adopted in NO compared to OP-FASTSLOW and OP-SLOWFAST during the initial 1000m. Finally, a faster starting opponent evokes higher power outputs by the participants in the initial 750m compared to a slower starting opponent. ConclusionThe present study is the first to show that the behavior of an opponent affects pacing-related decisions in laboratory-controlled conditions. Our findings support the recently proposed interdependence of perception and action, and emphasize the interaction with the environment as an important determinant for an athlete's pacing decisions, especially during the initial stages of a race.

Differences in visual information-seeking behavior between expert and novice time-trial cyclists

Introduction: Pacing can be defined as an ability to distribute available energy resources during the race (Hettinga et al. , 2006). It’s a determinant of athletic performance, affected by an interaction between previous experience, performance feedback and individual risk-traits (Micklewright et al. , 2014). Selective processing of internal physiological and external feedback information is a complex process that informs pace decision-making (Renfree et al. , 2014), but little is known about how athletes seek-out and interpret information to make pacing decisions. This study compared information-seeking behavior between novice and experienced cyclists. Methods : Novice (n=10) and experienced (n=10) cyclists performed two 16.09 km self-paced time-trials (TT’s), one week apart. Time-trials were performed on a Velotron cycle ergometer using a video simulated course. Performance information (power, speed, cadence, distance and time), heart rate and the 6-20 RPE scale were displayed in front of participants during TT’s. A head-mounted eye-tracker was used to measure the frequency and duration of gazes towards each type of information. Gaze was coded as ‘other’ when participants were not looking at any of the information specified above. Cumulative gaze duration for each information source was calculated as a percentage of TT completion time. Between and within-subjects ANOVA’s were used to compare performance, fixation times and fixation frequencies between groups and trials. Results : Performance between TT’s did not change for experts (27:55±1:21 vs. 27:42±1:30 mins:secs) or novices (30:53±3:14 vs. 30:16±2:56 mins:secs). Cycling speed in each segment was faster among experts compared to novices, but both groups maintained an even pace through the TT’s. In TT1, experts primarily looked at speed (30.1%) followed by other (19.3%) then distance (18.3%). Novices were less selective during TT1, looking at distance (21.6%), video (15.3%), other (14.3%), and power (13.4%) (Fig 1A). Experts looked at speed more in TT2 (Speed 33.4%, Distance 17.7%, and other 16%) and novices looked at the video less (Distance 23.1%, Speed 14.4%, Power 13.8%, Other 13.6% and Video 10.5%) (Fig1B). Differences in fixation time were found between groups for primary (P=0.003) and secondary sources of information (P=0.043) (Fig 2A). Differences were also found in frequency for primary (P=0.003) and secondary source of information (P=0.04) respectively (Fig. 2B) . Discussion: Experts were found to look at speed as their primary source of information compared to novices who looked at distance. This may indicate a preference for performance related decision-making in experts compared to a focus on task completion among novices.

Timing Of Glucose Supplementation To Optimize Performance In Repeated Bouts Of High Intensity Cycling

Athletes participating in short duration sprint events must carefully choose their fuel strategy to maximize performance. PURPOSE: To determine whether glucose feeding taken immediately before, early, or late in a series of high-intensity cycling exercises affected cycling performance. METHODS: 16 trained, male cyclists (> 6hr post-prandial) participated in the study and performed three, 4-km cycling time trials (T1, T2, T3) separated by 15 min of active recovery on four separate occasions. Subjects completed a familiarization visit followed by randomized visits comprised of a control visit (CNT), and three visits in which glucose feeding (40g) was given either before the first time trial (PRE1), before the second time trial (PRE2), or before the third time trial (PRE3). Sweet-placebo was given prior to the other time trials. Data were collected on a Velotron cycle ergometer. Blood glucose (BG) was measured upon arrival and before and after each trial by capillary sampling. RESULTS: Peak power output (PPO) in PRE1, PRE2 and CNT were significantly lower (-4.5%, -4.5%, and -2.5%, respectively) in T2 than T1 (p < 0.05). PPO in PRE2 and PRE3 were significantly lower (-6.3% and -4.5%, respectively) in T3 than T1 (p < 0.05). BG in PRE1 was significantly higher (+23.3%) before T1 than PRE3 (p < 0.05). In T2, BG was significantly higher (+19.4%) in PRE2 than PRE3 prior to T2 (p < 0.05). BG in PRE2 was significantly higher (+14.2%) prior to T2 than T1 (p < 0.05). BG in PRE2 and PRE3 continued to increase 20.8% and 29%, respectively before trial 3. BG in PRE2 was significantly higher (43.4%) than the control prior to T3 (p < 0.05). BG in PRE2 and PRE3 were significantly higher (37.8 and 26.8%, respectively) in T3 than T1 (p < 0.05). BG in PRE2 and PRE3 were significantly higher (20.7 and 29%, respectively) in trial 3 than trial 2 (p < 0.05). CONCLUSION: There was a reduction in performance in repeated high-intensity exercise bouts with glucose feeding after the initial exercise bout, but no significant decrease in performance with pre-exercise feeding or fasting. Therefore, in order to optimize performance, athletes undertaking repeated high-intensity exercise bouts should ingest glucose prior to exercise, but not between exercise bouts.

Fructose–Maltodextrin Ratio Governs Exogenous and Other CHO Oxidation and Performance

Fructose coingested with glucose in carbohydrate (CHO) drinks increases exogenous-CHO oxidation, gut comfort, and physical performance. This study aimed to determine the effect of different fructose-maltodextrin-glucose ratios on CHO oxidation and fluid absorption while controlling for osmolality and caloricity. In a crossover design, 12 male cyclists rode 2 h at 57% peak power then performed 10 sprints while ingesting artificially sweetened water or three equiosmotic 11.25% CHO-salt drinks at 200 mL·15 min, comprising weighed fructose and maltodextrin-glucose in ratios of 0.5:1 (0.5 ratio), 0.8:1 (0.8 ratio), and 1.25:1 (1.25 ratio). Fluid absorption was traced with D2O, whereas C-fructose and C-maltodextrin-glucose permitted fructose and glucose oxidation rate evaluation. The mean exogenous-fructose and exogenous-glucose oxidation rates were 0.27, 0.39, and 0.46 g·min and 0.65, 0.71, and 0.58 g·min in 0.5, 0.8, and 1.25 ratio drinks, representing mean oxidation efficiencies of 54%, 59%, and 55% and 65%, 85%, and 86% for fructose and glucose, respectively. With the 0.8 ratio drink, total exogenous-CHO oxidation rate was 18% (90% confidence interval, ±5%) and 5.2% (±4.6%) higher relative to 0.5 and 1.25 ratios, respectively, whereas respective differences in total exogenous-CHO oxidation efficiency were 17% (±5%) and 5.3% (±4.8%), associated with 8.6% and 7.8% (±4.2%) higher fructose oxidation efficiency. The effects of CHO ratio on water absorption were inconclusive. Mean sprint power with the 0.8 ratio drink was moderately higher than that with the 0.5 ratio (2.9%; 99% confidence interval, ±2.8%) and 1.25 ratio (3.1%; ±2.7%) drinks, with total- and endogenous-CHO oxidation rate, abdominal cramps, and drink sweetness qualifying as explanatory mechanisms. Enhanced high-intensity endurance performance with a 0.8 ratio fructose-maltodextrin-glucose drink is characterized by higher exogenous-CHO oxidation efficiency and reduced endogenous-CHO oxidation. The gut-hepatic or other physiological site responsible requires further research.

Influence of Competition on Performance and Pacing during Cycling Exercise

The study's purpose was to examine the influence of head-to-head (HH) competition on performance, pacing strategy, and bioenergetics during a 2000-m cycling task. Fourteen participants completed three 2000-m familiarization time trials (TTs) on a Velotron cycle ergometer, before completing an additional TT and a 2000-m simulated HH competition in a counterbalanced order. During the trials, a computer-generated image of the participants completing the 2000-m course was projected onto a screen positioned in front of the participants. Although participants believed they were competing against another individual during the HH competition, they were in fact competing against their best familiarization performance (FAM), replayed on the screen by the Velotron software. Performance was significantly faster in HH than in FAM or TT (184.6 ± 6.2, 187.7 ± 8.2, and 188.3 ± 9.5 s, respectively). Pacing profile in HH initially matched the FAM performance but was better maintained from 1000 m until the end of exercise. The higher power output during the latter part of the test was achieved by a greater anaerobic energy contribution, whereas the aerobic energy yield remained unchanged. HH competition encourages participants to increase their performance. This occurs primarily via an increased anaerobic energy yield, which seems to be centrally mediated, and is consistent with the concept of a physiologic reserve.

Visualization of the Passive Sink Phenomenon in Nonexercising Muscle Using 2 Sampling Sites: Consequences for Assessment and Training

Sampling sites for determining lactate concentration [La(-)] have been debated for years. To date, none of the research that has been completed has taken into consideration the muscle group that is active during exercise, sample site, and the passivity of nonexercising muscle, collectively. The purpose of this study was to determine if this passive sink phenomenon could be visualized by using common sampling methods immediately after exercise and during the recovery period from 2 sample sites. Eleven male cyclists completed a subject-specific trial on a Velotron cycle ergometer. Plasma [La(-)] was measured from the finger and toe immediately postexercise and every 5 minutes after, for 25 minutes after the cycling trial. All 3 analyses were significant (p < 0.05) with the sample site × sample time interaction, sample time main effect, and sample site main effect being reported, respectively: Wilks' λ = 0.079, F (5,6) = 13.932, p = 0.003, Wilks' λ = 0.012, F (5,6) = 94.804, p = 0.000, and Wilks' λ = 0.492, F (1,10) = 10.316, p = 0.009. Post hoc paired t-tests on computed mean differences between sample sites for each sample time revealed statistically significant differences (p < 0.05) between several time intervals. Further analysis also revealed significant differences (p < 0.05) in the sample site main effect at each collection time. Blood lactate samples need to be obtained from the limb containing the exercising muscle(s) to negate the passive sink effect that has been observed to occur in nonexercising muscles. This recommendation needs to be followed to better establish future training volumes and outcomes.

An Evaluation of 30-km Cycling Time Trial (TT30) Pacing Strategy Through Time-to-Exhaustion at Average TT30 Pace

A paucity of research is available on the optimal pacing strategy for cycling events longer than 4 km. Anecdotal evidence suggests that an even pacing strategy is most suitable; however, controlled studies have only determined that a slow start is more suitable than a fast start pacing strategy. Currently, it is unclear which strategy is more effective for endurance cycling time trials. This study sought to identify differences in 30-km cycling time trial (TT30) performance related to pacing strategies by comparing individually chosen pacing strategy with time-to-exhaustion (TE) at the average power output achieved during TT30. Eight moderately trained male cyclists (Vo2max = 50.9 +/- 5.2 mlxkgxmin) performed 2 TT30 tests and 2 TE tests at the average power output of TT30 on a Velotron cycle ergometer at the same time of day, separated by at least 48 hours. During TT30, participants generally chose to use a 'fast start' pacing strategy, cycling at a speed relative to the TT average (TTAvg) of 103.1 +/- 2.2% during the first 5 km. There was no significant difference in performance time between the TE test and TT30. Starting pace (TT0-5) was significantly correlated with finishing pace (TT25-30) (r = -0.91; p < 0.01) and TE (r = 0.85; p < 0.01). Subjects cycling at a relative starting speed (RS0-5) >105% had a significantly longer TE than subjects cycling at <105%, whereas TT30 performance time was not different between the two groups. The present investigation provided indirect evidence that a fast start pacing strategy decreases finishing speed and overall performance in TT30, and increased TT performance can be achieved by selecting a starting pace no more than 5% above TTAvg.

Accuracy of the Velotron Ergometer and SRM Power Meter

The purpose of this study was to determine the accuracy of the Velotron cycle ergometer and the SRM power meter using a dynamic calibration rig over a range of exercise protocols commonly applied in laboratory settings. These trials included two sustained constant power trials (250 W and 414 W), two incremental power trials and three high-intensity interval power trials. To further compare the two systems, 15 subjects performed three dynamic 30 km performance time trials. The Velotron and SRM displayed accurate measurements of power during both constant power trials (<1% error). However, during high-intensity interval trials the Velotron and SRM were found to be less accurate (3.0%, CI=1.6-4.5% and -2.6%, CI=-3.2--2.0% error, respectively). During the dynamic 30 km time trials, power measured by the Velotron was 3.7+/-1.9% (CI=2.9-4.8%) greater than that measured by the SRM. In conclusion, the accuracy of the Velotron cycle ergometer and the SRM power meter appears to be dependent on the type of test being performed. Furthermore, as each power monitoring system measures power at various positions (i.e. bottom bracket vs. rear wheel), caution should be taken when comparing power across the two systems, particularly when power is variable.

The Effects of Caffeine Ingestion on Time Trial Cycling Performance

The purpose of this work was to determine the effects of caffeine on high intensity time trial (TT) cycling performance in well-trained subjects. Six male cyclists with the following physical characteristics (mean +/- SD) age 30.7 +/- 12, height 179.3 +/- 7.5 cm, mass 70.0 +/- 7.5 kg, VO2max 65.0 +/- 6.3 mL.kg-1.min-1 undertook three 1-h TT performances, control (C), placebo (P) and caffeine (CAF), on a Velotron cycle ergometer conducted in a double-blind, random fashion. Subjects rested for 60 min and were then given CAF or P in a dose of 6 mg.kg-1 body mass and then commenced exercise after another 60 min of rest. Before ingestion, 60 min postingestion, and at the end of the TT, finger-prick blood samples were analyzed for lactate. The cyclists rode significantly further in the CAF trial (28.0 +/- 1.3 km) than they did in the C (26.3 +/- 1.5 km, P < .01) or P (26.4 +/- 1.5 km, P < .02) trials. No differences were seen in heart rate data throughout the TT (P > .05). Blood lactate levels were significantly higher at the end of the trials than either at rest or postingestion (P < .0001), but there were no differences between the three trial groups. On the basis of the data, we concluded that performance was improved with the use of a caffeine supplement.