The aim of the present study was to test the effects of different doses of anhydrous theacrine (3 and 6 mg·kg-1 of body mass) on 4 km cycling time trial performance. Nineteen (11 men and 8 women) cyclists (30.8 ± 10.0 years, 71.7 ± 11.8 kg, 170.1 ± 9.0 cm, and 17.0 ± 6.2% of body fat) completed three 4 km cycling time trials after ingesting either placebo, or 3 or 6 mg·kg-1 of body mass of theacrine. No significant differences (p < 0.05) were observed in time to cover the 4 km cycling time trial between the placebo, 3 mg·kg-1 of theacrine, and 6 mg·kg-1 of theacrine conditions. However, the intake of theacrine at the dose of 6 mg·kg-1 increased resting systolic and diastolic blood pressure (p < 0.05). Some side effects, such as gastrointestinal discomfort, perception of tachycardia, dizziness, headache, head pressure, hand tremor, and lack of disposition were reported after the ingestion of either 3 or 6 mg·kg-1 of body mass of theacrine. In conclusion, theacrine supplementation does not improve endurance performance and provokes side effects that might restrict its use as a supplement.

This study examined potential sex differences on performance and perceived fatigability during a whole-body endurance exercise performed under normoxia or moderate hypoxia. Nine male and eight female cyclists performed a 4-km cycling time-trial under normoxia or hypoxia conditions. Performance fatigability and its central and peripheral determinants were measured via pre- to post-exercise changes in maximal voluntary isometric contraction (IMVC), voluntary activation (VA), and potentiated twitch force (TwPt) of knee extensors, respectively. Perceived fatigability was characterized via rating of perceived exertion (RPE). Time to complete the trial was longer in hypoxia than normoxia in females (482 ± 24 vs 465 ± 21 s) and males (433 ± 30 vs 408 ± 31 s) (P = 0.039). There was no effect of sex or condition (P ≥ 0.370) for the magnitude of decrease in IMVC (female: normoxia = −14.3 ± 4.4 %, hypoxia = −11.8 ± 5.2 % vs male: normoxia = −13.1 ± 9.4 %, hypoxia = −12.9 ± 9.8 %), TwPt (female: normoxia = −34.4 ± 11.4 %, hypoxia = −31.8 ± 18.9 % vs male: normoxia = −30.5 ± 17.9 %, hypoxia = −31.9 ± 20.9 %), and VA (female: normoxia = −0.5 ± 2.3 %, hypoxia = −1.6 ± 1.6 % vs male: normoxia = 0.8 ± 2.2 %, hypoxia = −0.5 ± 1.3 %). RPE was higher in hypoxia than normoxia for both groups (P = 0.002). In conclusion, moderate hypoxia similarly impairs performance and perceived fatigability development in females and males during a 4-km cycling time-trial.

Exposure to air pollution has been a significant challenge in large cities as São Paulo, Brazil, particularly for individuals exercising outdoors. The increasing on ventilation (VE) during physical effort can lead to greater pollutant inhalation. Our goal in the present study evaluated whether air pollution exposure affects venous blood gases and if it has an impact on performance during a 50-km cycling time trial (TT). Ten male cyclists performed the TT in an environmental chamber under TRAP and filtered air conditions. Venous blood samples collected pre- and post-TT were analyzed for pH, PvCO2 (partial pressure of carbon dioxide in venous blood), PvO2 (partial pressure of oxygen in venous blood) hematocrit (Htc), hemoglobin (Hb), and oxygen saturation (SvO2). PM2.5 levels were significantly lower in filtered air (11.2 ± 4.7 μm/m3) than in TRAP (34.6 ± 10.8 μm/m3). There was no significant difference in mean power output between conditions (p = 0.907, d = 0.038). Blood gas parameters showed no condition effect or interaction, but time significantly affected PvO2 (p = 0.04), Hb (p < 0.01), Htc (p < 0.01), and PvCO2 (p = 0.02). These findings suggest recreationally trained cyclists experience no performance impairment under TRAP, with minimal changes in venous blood gas parameters.

We investigated whether caffeine ingestion reverses the deleterious effect of sleep restriction on high-intensity exercise (HIE) performance, and its impact on ventilatory, blood acidosis, and neuromuscular fatigue. Nine physically active men (29 ± 6 years, 176 ± 5 cm, 80.4 ± 7.4 kg) completed a session of HIE under: (1) habitual sleep plus placebo ingestion (HSP); (2) sleep restriction plus placebo ingestion (SRP); and (3) sleep restriction plus 5 mg.kg−1 of caffeine ingestion (SRC). Ventilatory responses were continually monitored, while blood H+, plasma lactate, maximal voluntary isometric contraction (MVIC), voluntary activation (VA), and quadriceps potentiated doublet-twitch force (PT) were assessed at pre-capsule ingestion, after completing 70

Purpose: To determine the effects of repeated Brazilian jiujitsu (BJJ) matches on neuromuscular fatigue in forearm-flexor and knee-extensor muscles. Methods: Twelve BJJ athletes (8 men and 4 women) performed a simulated BJJ tournament composed of four 8-minute matches interspersed by 16-minute intervals. Neuromuscular fatigue was assessed via prematch to postmatch(es) reductions in maximal voluntary isometric contraction (MVIC), voluntary activation, and potentiated twitch force (Ptwpot) in the forearm-flexor and knee-extensor muscles. Results: The MVIC of the knee extensors and forearm flexors reduced from prematch 1 to postmatch 2 and remained suppressed until postmatch 4 (P < .034). The voluntary activation of the knee extensors declined only after match 4, whereas the voluntary activation of the forearm flexors did not change throughout the matches (P = .102). Ptwpot of knee extensors decreased from prematch 1 to postmatch 1 (P < .001) and remained reduced until postmatch 4 (P < .001). Ptwpot of the forearm flexors reduced after every match (P < .010), with complete recovery occurring only before the second match (P = .99). The magnitude of the prematch-to-postmatch reduction in Ptwpot was lower in knee extensors than in forearm flexors (P = .044). Conclusions: Repeated BJJ matches induced neuromuscular fatigue, mainly due to impairments in muscle contractile function (ie, peripheral fatigue). The time between BJJ matches seems to be insufficient to allow complete recovery of neuromuscular function, which may influence performance during subsequent matches.

This review provides the current state of knowledge regarding the use of nutritional nanocompounds on exercise performance. The reviewed studies used the following nanocompounds: resveratrol-loaded lipid nanoparticles, folic acid into layered hydroxide nanoparticle, redox-active nanoparticles with nitroxide radicals, and iron into liposomes. Most of these nutritional nanocompounds seem to improve performance in endurance exercise compared to the active compound in the non-nanoencapsulated form and/or placebo. Nutritional nanocompounds also induced the following physiological and metabolic alterations: 1) improved antioxidant activity and reduced oxidative stress; 2) reduction in inflammation status; 3) maintenance of muscle integrity; 4) improvement in mitochondrial function and quality; 5) enhanced glucose levels during exercise; 6) higher muscle and hepatic glycogen levels; and 7) increased serum and liver iron content. However, all the reviewed studies were conducted in animals (mice and rats). In conclusion, nutritional nanocompounds are a promising approach to improving exercise performance. As the studies using nutritional nanocompounds were all conducted in animals, further studies in humans are necessary to better understand the application of nutritional nanocompounds in sport and exercise science.

Purpose : To characterize the time structure of K1 kickboxing matches of Glory World Series (Glory) and to determine potential differences between winners and losers. Methods : Seventeen matches of Glory 2019 (17 first rounds, 13 second rounds, and 8 third rounds) were video-analyzed to quantify (1) the time expended in high- and low-intensity activity and pauses, (2) the number and pattern of attacks, and (3) the number of effective attacks. Fighters were professional male athletes (age 27.9 [2.7] y) of the middle-weight category (85 kg). The number and the pattern of attacks and the number of effective attacks were compared between winners and losers. Results : The mean times expended in high- and low-intensity activity and pauses were 234.6 (133.9) seconds, 97.4 (60.1) seconds, and 36.0 (19.9) seconds, respectively, resulting in an effort-to-pause ratio of ∼1.8:1. Compared with losers, winners presented (1) a greater number of attacks in the second round ( P = .004) and entire match ( P = .009), (2) a greater number of attacks containing 3 attacks in sequence in the second round ( P = .001) and attacks containing >3 attacks in the third round ( P = .049), and (3) a greater number of effective attacks in the second round ( P = .011) and entire match ( P = .008). Conclusions : The findings of the present study indicate that K1 kickboxing in Glory matches presents a ∼1.8:1 effort-to-pause ratio and that winners perform more attacks, effective attacks, and attacks in sequence. These data provide useful insights to improve the training specificity of kickboxing athletes.

OBJECTIVE:To investigate the acute effects of ingesting a beverage containing guarana (Paullinia cupana) seed powder on performance during field tests related to physical capacities that are determinants of soccer performance, such as lower limb power, sprint, agility, and the capacity to carry out intermittent exercise. METHODS:The study was conducted using a randomized, crossover, and counterbalanced design, with a beverage containing guarana or placebo administered in a double-blind manner. Twenty-seven under-17 soccer players of a professional soccer club performed a battery of tests 60 min after the ingestion of guarana (3 g of the fruit seed powder) or placebo. Trials were performed with a 7-day washout period. The battery of tests included a countermovement jump test, sprints of 10 and 20 m, an Illinois agility test, and a Yo-Yo Intermittent Recovery Test level 1 (YYIR1). RESULTS:Guarana ingestion did not improve countermovement jump, sprints, or agility (p > 0.05). However, guarana ingestion increased the distance covered in the YYIR1, compared with placebo ingestion (p = 0.01). CONCLUSION:Acute ingestion of guarana improves the capacity to perform intermittent exercise in soccer players but seems to be ineffective to improve lower limb power, sprint, and agility.

Putti, Germano Marcolino, Gabriel Peinado Costa, Matheus Silva Norberto, Carlos Dellavechia de Carvalho, Romulo Cassio de Moraes Bertuzzi, and Marcelo Papoti. Use of inter-effort recovery hypoxia as a new approach to improve anaerobic capacity and time to exhaustion. High Alt Med Biol 00:000-000, 2024.-Background: Although adding hypoxia to high-intensity training may offer some benefits, a significant problem of this training model is the diminished quality of the training session when performing efforts in hypoxia. The purpose of this study was to investigate the effects of training and tapering combined with inter-effort recovery hypoxia (IEH) on anaerobic capacity, as estimated by alternative maximum accumulated oxygen deficit (MAODALT) and time to exhaustion (TTE).Methods: Twenty-four amateur runners performed, for 5 weeks, 3 sessions per week of training consisted of ten 1-minute bouts at 120% (weeks 1-3) and 130% (weeks 4 and 5) of maximum velocity (VMAX) obtained in graded exercise test, separated by a 2-minute interval in IEH (IEH, n = 11, FIO2 = 0.136) or normoxia (NOR, n = 13, fraction of inspired oxygen = 0.209). Before training, after training, and after 1 week of tapering, a graded exercise test and a maximal effort to exhaustion at 120% of VMAX were performed to determine TTE and MAODALT. The results were analyzed using generalized linear mixed models, and a clinical analysis was also realized by the smallest worthwhile change.Results: MAODALT increased only in IEH after training (0.8 +/- 0.5 eq.lO2) and tapering (0.8 +/- 0.5 eq.lO2), with time x group interaction. TTE increased for the pooled groups after taper (23 +/- 11 seconds) and only for IEH alone (29 +/- 16 seconds). Clinical analysis revealed a small size increase for NOR and a moderate size increase for IEH.Conclusions: Although the effects should be investigated in other populations, it can be concluded that IEH is a promising model for improving anaerobic performance and capacity. World Health Organization Universal Trial Number: U1111-1295-9954. University's ethics committee registration number: CAAE: 32220020.0.0000.5659

The present study investigated the reliability and sensitivity of a wearable near-infrared spectroscopy (wNIRS) device in moderate and heavy exercise intensity domains. On three separate days, eleven males performed an incremental test to exhaustion, and in the following visits, four submaximal constant-load bouts (i.e., test and retest) were performed in the moderate-intensity domain (100 and 130 W) and heavy-intensity domain (160 and 190 W). The local tissue oxygen saturation index (SmO2) and pulmonary oxygen uptake (V̇O2) were measured continuously. The absolute SmO2 and V̇O2 values and the change (Δ) from the 3rd to 6th min of exercise were calculated. There was good reliability for SmO2 measurements, as indicated by the high intraclass correlation coefficient analysis (ICC ≥0.84 for all) and low coefficient of variation between the two trials (CV ≤4.1% for all). Steady-state responses were observed for SmO2 and V̇O2 from the 3rd to the 6th min in the two moderate-intensity bouts (P>0.05), whereas SmO2 decreased and V̇O2 increased from the 3rd to the 6th min in the two heavy-intensity bouts (P<0.05). Together, these findings suggested that the SmO2 measured with a wNIRS device is reliable and sensitive to track local metabolic changes provoked by slight increments in exercise intensity.

BACKGROUND:The influence of exhaustive whole-body exercise and caffeine ingestion on electromechanical delay (EMD) has been underexplored. This study investigated the effect of exhaustive cycling exercise on EMD and other parameters of muscle contractile properties and the potential ability of caffeine to attenuate the exercise-induced impairments in EMD and muscle contractile properties. METHODS:Ten healthy men cycled until exhaustion (88±2% of V̇O2max) on two separate days after ingesting caffeine (5 mg.kg-1 of body mass) or cellulose (placebo). Parameters of muscle contractile properties of the quadriceps muscles were assessed via volitional and electrically evoked isometric contractions, performed before and 50 minutes after ingestion of the capsules, and after exercise. Muscle recruitment during volitional contractions was determined via surface electromyography. RESULTS:Exhaustive cycling exercise did not affect volitional and relaxation EMD (P>0.05) but increased evoked EMD. In addition, the exhaustive cycling exercise also increased muscle recruitment at the beginning of volitional isometric muscle contraction (P<0.05). The peak twitch force, maximal rate of twitch force development, and twitch contraction time were all compromised after exhaustive cycling exercise (P<0.05). Acute caffeine ingestion had no effect on muscle contractile properties (P>0.05), except that caffeine increased twitch contraction time at postexercise (P<0.05). CONCLUSIONS:Exercise-induced decline in peripheral components of the EMD might be compensated by an increase in the muscle recruitment. In addition, acute caffeine ingestion had minimal influence on exercise-induced changes in muscle contractile proprieties.

Purpose: To compare the development of fatigability during a moderate-intensity cycling exercise between women with fibromyalgia (FM) and control women (CON) after acute ingestion of caffeine and placebo. Methods: Ten FM and 10 CON women performed a 30-min moderate-intensity cycling exercise 1 h after the ingestion of a capsule containing either caffeine or a placebo. Fatigability and its central and peripheral determinants were determined via changes from pre- to post-15 and post-30 min of exercise in maximal voluntary isometric contractions, voluntary activation (VA), and quadriceps potentiated twitch torque (Q(tw-pot)), respectively. Heart rate, muscle oxygen saturation, perceptive responses, mood state, localized and widespread pain, and sleepiness were also monitored during and after exercise. Results: There was a time versus group interaction for maximal voluntary isometric contraction and VA (P < 0.001) but not for Q(tw-pot) (P = 0.363), indicating a greater rate of fatigability development, mainly caused by central mechanisms, in the FM than in the CON group. There was also a main effect of condition for VA (P = 0.011), indicating that caffeine attenuates central mechanisms of fatigability in both groups. Caffeine ingestion also increased muscle oxygenation, perceived vigor, and energy, and decreased leg muscle pain, sleepiness, and perceived fatigue in both groups. However, caffeine improved perceived pleasure/displeasure and exercise adherence likelihood only in the FM group. Conclusions: Compared with CON, women with FM present a greater rate of fatigability during exercise, mainly of central origin. Caffeine seems to be a promising bioactive to counteract the central mechanisms of fatigability and improve the exercise experience among FM women.

It has been assumed that exercise intensity variation throughout a cycling time trial (TT) occurs in alignment of various metabolic changes to prevent premature task failure. However, this assumption is based on target metabolite responses, which limits our understanding of the complex interconnection of metabolic responses during exercise. The current study characterized the metabolomic profile, an untargeted metabolic analysis, after specific phases of a cycling 4-km TT. Eleven male cyclists performed three separated TTs in a crossover counterbalanced design, which were interrupted at the end of the fast-start (FS, 600 ± 205 m), even-pace (EP, 3600 ± 190 m), or end-spurt (ES, 4000 m) phases. Blood samples were taken before any exercise and 5 min after exercise cessation, and the metabolomic profile characterization was performed using Nuclear Magnetic Resonance metabolomics. Power output (PO) was also continually recorded. There were higher PO values during the FS and ES compared to the EP (all p < 0.05), which were accompanied by distinct metabolomic profiles. FS showed high metabolite expression in TCA cycle and its related pathways (e.g., glutamate, citric acid, and valine metabolism); whereas, the EP elicited changes associated with antioxidant effects and oxygen delivery adjustment. Finally, ES was related to pathways involved in NAD turnover and serotonin metabolism. These findings suggest that the specific phases of a cycling TT are accompanied by distinct metabolomic profiles, providing novel insights regarding the relevance of specific metabolic pathways on the process of exercise intensity regulation.

There is a lack of evidence on the additional benefits of combining caffeine (CAF) and creatine (CRE) supplementation on anaerobic power and capacity. Thus, the aim of the present study was to test the effects of combined and isolated supplementation of CAF and CRE on anaerobic power and capacity. Twenty-four healthy men performed a baseline Wingate anaerobic test and were then allocated into a CRE (n = 12) or placebo (PLA; n = 12) group. The CRE group ingested 20 g/day of CRE for 8 days, while the PLA group ingested 20 g/day of maltodextrin for the same period. On the sixth and eighth days of the loading period, both groups performed a Wingate anaerobic test 1 hr after either CAF (5 mg/kg of body mass; CRE + CAF and PLA + CAF conditions) or PLA (5 mg/kg of body mass of cellulose; CRE + PLA and PLA + PLA conditions) ingestion. After the loading period, changes in body mass were greater (p < .05) in the CRE (+0.87 ± 0.23 kg) than in the PLA group (+0.13 ± 0.27 kg). In both groups, peak power was higher (p = .01) in the CAF (1,033.4 ± 209.3 W) than in the PLA trial (1,003.3 ± 204.4 W), but mean power was not different between PLA and CAF trials (p > .05). In conclusion, CAF, but not CRE ingestion, increases anaerobic power. Conversely, neither CRE nor CAF has an effect on anaerobic capacity.

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.

Air pollution is among the leading environmental threats to health around the world today, particularly in the context of sports and exercise. With the effects of air pollution, pollution episodes (eg, wildfire conflagrations) and climate change becoming increasingly apparent to the general population, so have their impacts on sport and exercise. As such, there has been growing interest in the sporting community (ie, athletes, coaches, and sports science and medicine team members) in practical personal-level actions to reduce the exposure to and risk of air pollution. Limited evidence suggests the following strategies may be employed: minimising all exposures by time and distance, monitoring air pollution conditions for locations of interest, limiting outdoor exercise, using acclimation protocols, wearing N95 face masks and using antioxidant supplementation. The overarching purpose of this position statement by the Canadian Academy of Sport and Exercise Medicine and the Canadian Society for Exercise Physiology is to detail the current state of evidence and provide recommendations on implementing these personal strategies in preventing and mitigating the adverse health and performance effects of air pollution exposure during exercise while recognising the limited evidence base.

Vegan diets are virtually absent in carnosine, which may result in reduced buffering capacity and performance during sprint interval exercise. Thus, vegans might be more benefited by ingestion of an extracellular buffer for improving sprint performance than omnivores. In the present study, we investigated the effects of sodium bicarbonate (NaHCO3 -) ingestion on performance during a sprint interval exercise in vegans and omnivores. Ten (five males and five females) vegans and nine (four males and five females) omnivores performed four 30-second sprints (5-minute rest between sprints) after ingesting either placebo (cellulose) or NaHCO3 - (0.1·kg-1 body mass at 120, 90 and 60 minutes prior exercise). There was a higher peak and mean power in bout 1 and 2 than bouts 3 and 4 (main effect of sprint, p = .001). However, NaHCO3 - ingestion had no effect on peak and mean power during the four sprints in both vegans and omnivores groups (main effect of condition, p = .590 and 0.443). There were also no differences in sprint performance between groups (main effect of group, p = .621 and p = .902). In conclusion, acute ingestion of sodium bicarbonate does not improve performance during sprint interval exercise in both vegans and omnivores. Cite this article as: Henrique Marinho, A., Pfeiffer, A., Tomazini, F., Juan Senoski, S., Giannini Artioli, G., Bertuzzi, R., & Eduardo Lima-Silva, A. (2023). Sodium bicarbonate supplementation does not improve repeated sprint performance in vegans and omnivores. Research in Sports Science, 13(1), 17-22.

Objectives. - Whether performance fatigability and its determinants (i.e., peripheral and central fatigue) after cycling exercise performed at extreme- and severe-intensity domains are of similar magnitude is unknown. In the current study, we investigated the levels of performance fatigability and peripheral and central fatigue in nine young female after a cycling exercise performed until the limit of tolerance at extreme- (i.e., 140% of peak power output) and severe-intensity domains (80% of the difference between gas exchange threshold and peak power output). Equipment and methods. - The level of maximal voluntary isometric contraction (MVC), potentiated quadriceps twitch force evoked by single pulse (Qtw), and voluntary activation (VA) were measured pre- and post-exercise.Results. - The MVC (a marker of performance fatigability) decreased from pre- to post-exercise( P < 0.05) in the extreme- (-10 +/- 8%) and severe-intensity (-10 +/- 10%) exercises. The Qtw(amarker of peripheral fatigue) reduced similarly from pre- to post-exercise (P < 0.05) in theextreme(-18 +/- 15%) and severe-intensity (-10 +/- 17%) exercises. The VA (a marker of centralfatigue) did not reduce from pre- to post-exercise in either severe- (2 +/- 7%) or extreme-intensity(2 +/- 7%) exercises (P > 0.05). Conclusions. - These findings suggest a similar amount of performance fatigability and peripheral fatigue after severe- and extreme-intensity cycling exercises in young female, which is inaccordance with the concept that exercises performed above critical power until task failureattain a common level of peripheral fatigue regardless of exercise intensity. (c) 2023 Elsevier Masson SAS. All rights reserved.

OBJECTIVE:The impact of a vegan diet on sprint interval exercise performance is unknown. Thus, the purpose of the present study was to compare performance during a sprint interval exercise between omnivores and vegans. METHODS:Nine healthy omnivores (4 men and 5 women) and nine healthy vegans (4 men and 5 women), with similar levels of daily physical activity, performed four bouts (5-min rest between bouts) of a 30-s all-out sprint exercise on a cycle ergometer. Peak power, mean power, fatigue index, and time to reach maximal power output in each bout were recorded. RESULTS:There was a higher peak power in bouts 1 and 2 compared with bouts 3 and 4 (p < 0.02), and a higher mean power in bout 1 compared with bouts 2, 3 and 4 (p < 0.02). However, for all bouts, there were no significant difference between omnivores and vegans in peak power (7.60 ± 1.55 vs. 8.16 ± 1.27, 7.52 ± 1.6 vs 7.61 ± 0.73, 7.00 ± 1.44 vs. 7.00 ± 1.05 and 6.95 ± 1.42 vs. 6.49 ± 0.90 W.kg-1, all p > 0.05) and in mean power (5.35 ± 0.93 vs. 5.69 ± 0.84, 5.10 ± 0.88 vs. 5.21 ± 0.49, 4.79 ± 0.81 vs. 4.79 ± 0.45 and 4.81 ± 0.81 vs. 4.69 ± 0.47 W.kg-1, all p > 0.05). Fatigue index and time to reach maximal power output were not affected by diet or bouts (all p > 0.05). CONCLUSIONS:These findings indicate that a vegan diet does not compromise sprint interval exercise performance.

We examined whether endurance performance and neuromuscular fatigue would be affected by caffeine ingestion during closed- and open-loop exercises. Nine cyclists performed a closed-loop (4,000-m cycling time trial) and an open-loop exercise (work rate fixed at mean power of the closed-loop trial) 60 min after ingesting caffeine (CAF, 5 mg/kg) or placebo (PLA, cellulose). Central and peripheral fatigue was quantified via pre- to post-exercise decrease in quadriceps voluntary activation and potentiated twitch force, respectively. Test sensitivity for detecting caffeine-induced improvements in exercise performance was calculated as the mean change in time divided by the error of measurement. Caffeine ingestion reduced the time of the closed-loop trial (PLA: 375.1±14.5 s vs CAF: 368.2±14.9 s, P=0.024) and increased exercise tolerance during the open-loop trial (PLA: 418.2±99.5 s vs CAF: 552.5±106.5 s, P=0.001), with similar calculated sensitivity indices (1.5, 90%CI: 0.7-2.9 vs 2.8, 90%CI: 1.9-5.1). The reduction in voluntary activation was more pronounced (P=0.019) in open- (-6.8±8.3%) than in closed-loop exercises (-1.9±4.4%), but there was no difference between open- and closed-loop exercises for the potentiated twitch force reduction (-25.6±12.8 vs -26.6±12.0%, P>0.05). Caffeine had no effect on central and peripheral fatigue development in either mode of exercise. In conclusion, caffeine improved endurance performance in both modes of exercise without influence on post-exercise central and peripheral fatigue, with the open-loop exercise imposing a greater challenge to central fatigue tolerance.