The aim of this study was to explore sex differences in neuromuscular fatigue during a severe-intensity cycling exercise. Twenty-four healthy participants (12 women and 12 men) cycled at 80% of the difference between gas exchange threshold and maximal power output to the limit of tolerance. Neuromuscular fatigue was assessed by the decrease in maximal voluntary contraction of the knee extensors before and after exercise, and central and peripheral fatigue was measured by the decrease in voluntary activation and quadriceps potentiated twitch force before and after exercise. Women presented shorter time to task failure (P=0.025) and lower levels of neuromuscular fatigue (P=0.006) and peripheral fatigue (P<0.001) than men. Women and men showed different patterns of muscle activation during exercise, with women presenting greater muscle activation at the beginning of exercise and sustaining this elevated muscle activation throughout exercise, while men increased muscle activation from the beginning to the end of exercise. In conclusion, women had lower levels of neuromuscular fatigue, mainly caused by lower levels of peripheral fatigue, and a different muscle activation pattern in an exhaustive severe-intensity cycling exercise.

The aim of the present study was to describe the use of tapering, carbohydrate (CHO) supercompensation, and supplementation strategies self-reported by athletes in the Olympic triathlon category. A total of 72 triathletes (61 males and 11 females) answered an online questionnaire about their training and performance, supercompensation strategies, carbohydrate supplementation, and use of supplements and other ergogenic substances. The information was summarized and subjected to descriptive analysis. Shapiro-Wilk test was applied to check data normality. The t-test was used to investigate differences in the analyzed variables between sexes. Almost all triathletes reported to have performed tapering (93.05%) and approximately half of them adopted a CHO supercompensation strategy (48.61%); updated CHO supercompensation was the most used strategy (27.77%). Most participants (86.11%) used CHO supplementation during competitions, but in amounts below the 60 g/h recommended for most athletes (96.77%). Thus, since few triathletes performed supercompensation, in addition to the insufficient amount of supplemented carbohydrate taken by them, it could be concluded that triathletes were not sufficiently aware of nutritional recommendations or did not adopt them.

Abstract 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.

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.

The aim of this study was to describe the muscle function, architecture, and composition of long-distance master runners, and verify the association between age and these variables. Additionally, different clusters of runners were compared based on age and training variables. Forty male runners (≥50 years) reported their training routine and had their muscle function evaluated through maximum knee extensor isometric peak torque (PT) assessed with an isokinetic dynamometer. The cross-sectional area (CSA), pennation angle (PA), fascicle length (FL), muscle thickness (MT), and echo intensity (EI) were evaluated through ultrasound (muscle architecture and composition). The participants were 58.7±6.2 years old and had been training for 18.4±10.3 years, 4 sessions/week with 298.8±164.7 min/week of training. The absolute torque was 226.92±63.44 N·m, and the specific torque (PT/CSA) was 7.29±3.78 N·m/cm2. Regarding muscle architecture, the phase angle was 17.34±4°, the fascicle angle 6.78±1.04 cm, muscle thickness 2.93±0.56 cm, and the cross-sectional area 21.24±5.88 cm2. Concerning muscle composition, the master runners showed echo intensity values of 62.05±11.68 AU. The analysis demonstrated a weak and negative association between age and some muscle architecture variables (CSA and MT) and muscle function (PT). No association was verified between age and muscle composition (EI). Age partially explained CSA, MT, and muscle function changes (13, 11, and 14%, respectively). Participants' high level of physical training might have contributed to the low association between these variables and the lack of association with muscle composition.

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. allout all out evenpacing even selfpaced self paced study 4km 4 familiarization , trial) order 32.3±7.2 32372 32 3 7 2 (32.3±7. old O V̇O2peak VO2peak VOpeak V O2peak peak (V̇O2peak 4304 0 4.3±0. L/min Lmin L min completed 1 ∼10 10 (∼1 s s) allout+mean alloutmean out+mean mean (all-out+mean) 5 allout+5%mean. allout5mean out+5%mean . (all-out+5%mean) P=0.001 P0001 P 001 (P=0.001 P=0.99 P099 99 (P=0.99 3798139 379 8 13 9 379.8±13. 3800160 380 16 380.0±16. allout+5%mean 3802115 11 380.2±11. s. effort 32.3±7. 3237 (32.3±7 VO Opeak 430 4.3±0 ∼1 (∼ outmean (all-out+mean out5mean (all-out+5%mean P=0.00 P000 00 (P=0.00 P=0.9 P09 (P=0.9 379813 37 379.8±13 380016 38 380.0±16 380211 380.2±11 32.3±7 323 (32.3± 43 4.3± ∼ ( P=0.0 P00 (P=0.0 P=0. P0 (P=0. 37981 379.8±1 38001 380.0±1 38021 380.2±1 32.3± (32.3 4.3 P=0 (P=0 3798 379.8± 3800 380.0± 3802 380.2± 32.3 (32. 4. P= (P= 379.8 380.0 380.2 32. (32 (P 379. 380. (3

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.

The present study compared the effects of a footwear designed to enhance energy return (thermoplastic polyurethane, TPU) vs minimalist shoes on running economy (RE) and endurance performance. In this counterbalanced and crossover design study, 11 recreational male runners performed two submaximal constant-speed running tests and two 3-km time-trials with the two shoe models. Oxygen uptake was measured during submaximal constant-speed running tests in order to determine the RE at 12 km/h and oxygen cost of running (CTO2) at individual average speed sustained during the 3-km running time-trials wearing either of the two shoes. Our results revealed that RE was improved (2.4%) with TPU shoes compared with minimalist shoes (P=0.01). However, there was no significant difference for CTO2 (P=0.61) and running performance (P=0.52) comparing the TPU (710±60 s) and the minimalist (718±63 s) shoe models. These novel findings demonstrate that shoes with enhanced mechanical energy return (i.e. TPU) produced a lower energy cost of running at low (i.e., 12 km/h) but not at high speeds (i.e., average speed sustained during the 3-km running time-trial, ∼15 km/h), ultimately resulting in similar running performance compared to the minimalist shoe.

The main movements of artistic swimming demand various physical capacities such as flexibility, strength, power, and muscular endurance. The use of ergogenic resources to potentialize performance in this sport, however, is underexplored and deserves investigation. In the present study, we tested whether caffeine ingestion would improve the execution of movements that are essential in a typical figure competition or routines in artistic swimming (i.e., amplitude in the Ariana, height in the Boost and Barracuda, and time maintained in the Stationary Scull techniques). Sixteen experienced female athlete artistic swimmers (17.4±3.2 years of age, 5.6±2.8 years of artistic swimming practice) performed several movements of artistic swimming after having ingested a capsule containing caffeine (5 mg/kg body mass) or cellulose (placebo). Compared to the placebo, caffeine improved latero-lateral amplitude during the Ariana (P=0.035), the height of the Boost and Barracuda (P=0.028 and 0.009), and maintained duration in Stationary Sculling (P=0.012). Bayes factor analysis, however, indicated substantial evidence of a positive effect of caffeine only on the Barracuda and Stationary Scull techniques. These findings indicated that caffeine improved performance during specific artistic swimming movements. Coaches and athletes should consider caffeine ingestion in their supplementation plans.

Sedentary time is associated with increased obesity in police officers. Caffeine intake may reduce sedentary time but it has not been extensively investigated. In the present study, the effect of caffeine ingestion on sedentary time was investigated in obese police officers. Fourteen obese police officers ingested either 5 mg/kg of caffeine or cellulose (placebo) for six days. Information on inactivity time, time spent with physical activities, self-reported perception of tiredness, and physical activity disposition was obtained daily during the intervention period. Sedentary and physical activity times were divided into two intraday periods (T1: 08:00 am-02:00 pm and T2: 02:00 pm-08:00 pm). Caffeine intake decreased the sedentary time in both T1 (79.2±2.2%) and T2 (79.1±2.5%), when compared with T2 of the placebo condition (81.1±3.6%, P<0.05). Caffeine intake also increased the time spent on light physical activities in T1 and T2 (17±2 and 18±2%), when compared with T2 of the placebo condition (16±3%, P<0.05). In addition, sedentary time increased and light physical activity time decreased from T1 to T2 in the placebo (P<0.001) but not in the caffeine condition (P=0.81). Caffeine intake had no effect on tiredness (P>0.05), but it increased the self-reported physical activity disposition compared to the placebo condition (4.5±2.7 vs 3.2±2.3 units, P<0.05). Caffeine intake reduced the sedentary time and increased the time spent on light physical activities of obese police officers, which seems to be related to a higher disposition for the practice of physical activity.

We investigated the effect of caffeine ingestion combined with a 2-wk sprint interval training (SIT) on training-induced reductions in body adiposity. Twenty physically-active men ingested either 5 mg/kg of cellulose as a placebo (PLA, n=10) or 5 mg/kg of caffeine (CAF, n=10) 60 min before each SIT session (13×30 s sprint/15 s of rest). Body mass and skinfold thickness were measured pre- and post-training. Energy expenditure was measured at rest, during exercise, and 45 min after exercise in the first SIT session. Body fat was similar between PLA and CAF groups at pre-training (P>0.05). However, there was a significant decrease in body fat after training in the CAF group (−5.9±4.2%, P<0.05) but not in PLA (1.5±8.0%, P>0.05). There was no difference in energy expenditure at rest and during exercise between PLA and CAF groups (P>0.05), but the post-exercise energy expenditure was 18.3±21.4% greater in the CAF than in the PLA group (P<0.05). In conclusion, caffeine ingestion before SIT sessions induced a body fat loss that may be associated with higher post-exercise energy expenditure.

The objective of this study was to verify the agreement between pre-programmed and executed pacing during race walking and whether level of the athletes experience and performance influenced this relationship. Twenty-nine national and international race walkers participated in this study (14 males, 24.0±7.1 years old, and 15 females, 23.3±7.3 years old). Pre-programmed pacing for 10- and 20-km official walking races was self-selected via demonstrative pacing charts prior to races, while executed pacing was analyzed by a specialist investigator via an individual plot of current velocity versus distance. There was no agreement between pre-programmed and executed pacing (P=0.674). There was no association between the ability to match the pre-programmed pace with the executed pace and race walking experience or level of performance. Low- and high-performance athletes pre-programmed a similar pacing profile (P=0.635); however, high-performance athletes generally executed an even pacing strategy, while low-performance athletes generally adopted a positive pacing strategy (P=0.013). Race walkers did not faithfully match their pre-programmed with their executed pacing, and this seemed to be independent of previous experience and level of performance. High-performance athletes, however, tended to execute an even pacing strategy, even though this had not been pre-programmed.

The aim of this study was to test the hypothesis that reduced pre-exercise carbohydrate (CHO) availability potentiates fat oxidation after an exhaustive high-intensity exercise bout. Eight physically active men underwent a high-intensity exercise (∼95% V̇O2max) until exhaustion under low or high pre-exercise CHO availability. The protocol to manipulate pre-exercise CHO availability consisted of a 90-min cycling bout at ∼70% V̇O2max + 6 × 1-min at 125% V̇O2max with 1-min rest, followed by 48 h under a low- (10% CHO, low-CHO availability) or high-CHO diet (80% CHO, high-CHO availability). Time to exhaustion was shorter and energy expenditure (EE) lower during the high-intensity exercise in low- compared to high-CHO availability (8.6±0.8 and 11.4±1.6 min, and 499±209 and 677±343 kJ, respectively, P<0.05). Post-exercise EE was similar between low- and high-CHO availability (425±147 and 348±54 kJ, respectively, P>0.05), but post-exercise fat oxidation was significantly higher (P<0.05) in low- (7,830±1,864 mg) than in high-CHO availability (6,264±1,763 mg). The total EE (i.e., exercise EE plus post-exercise EE) was similar between low- and high-CHO availability (924±264 and 1,026±340 kJ, respectively, P>0.05). These results suggest that a single bout of high-intensity exercise performed under low-CHO availability increased post-exercise fat oxidation, and even with shorter exercise duration, both post-exercise EE and total EE were not impaired.

This study analyzed the influence of a 4-week high-intensity interval training on the pacing strategy adopted by runners during a 5-km running trial. Sixteen male recreational long-distance runners were randomly assigned to a control group (CON, n=8) or a high-intensity interval training group (HIIT, n=8). The HIIT group performed high-intensity interval-training twice per week, while the CON group maintained their regular training program. Before and after the training period, the runners performed an incremental exercise test to exhaustion to measure the onset of blood lactate accumulation, maximal oxygen uptake (VO2max), and peak treadmill speed (PTS). A submaximal constant-speed test to measure the running economy (RE) and a 5-km running trial on an outdoor track to establish pacing strategy and performance were also done. During the 5-km running trial, the rating of perceived exertion (RPE) and time to cover the 5-km trial (T5) were registered. After the training period, there were significant improvements in the HIIT group of ∼7 and 5% for RE (P=0.012) and PTS (P=0.019), respectively. There was no significant difference between the groups for VO2max (P=0.495) or onset of blood lactate accumulation (P=0.101). No difference was found in the parameters measured during the 5-km trial before the training period between HIIT and CON (P>0.05). These findings suggest that 4 weeks of HIIT can improve some traditional physiological variables related to endurance performance (RE and PTS), but it does not alter the perception of effort, pacing strategy, or overall performance during a 5-km running trial.

RESUMO Nos últimos anos, tem-se observado um aumento no consumo de alimentos diet e light por adolescentes ou por aqueles que estão à procura de uma alimentação com baixo teor calórico, surgindo, assim, diversos edulcorantes, como o aspartame. Porém, seu consumo ainda gera polêmica, devido a muitos dados contraditórios e inconclusivos. Diante disso, objetivou-se avaliar os efeitos da suplementação de aspartame sobre ingestão alimentar, parâmetros físicos, bioquímicos e histopatológicos em 18 ratos machos da linhagem Wistar, com cinco semanas de vida (ratos jovens), tratados durante 21 dias. Os animais foram distribuídos aleatoriamente em dois grupos: grupo controle (GC) - tratados com água destilada por gavagem, e o grupo aspartame (GA) - tratados diariamente com 2mL/100g/dia de aspartame. Todos os animais receberam ração comercial (Essence(r)) e água ad libitum. O controle da ingestão alimentar foi registrado semanalmente. Foram aferidos os parâmetros físicos por meio da análise do peso corporal, da circunferência toráxica, da circunferência abdominal, do comprimento vértice-cóccix, da gordura abdominal total e do cálculo do índice de massa corporal; os parâmetros bioquímicos foram analisados por meio da glicemia, da lipoproteína de alta densidade e dos triglicerídeos; além de tais análises, foi realizado o estudo histopatológico do fígado. Durante todo o experimento, os ratos tratados com aspartame apresentaram um aumento significativo no peso corpóreo e na ingestão alimentar quando comparados ao grupo controle. Não houve diferença nas demais análises tanto físicas, quanto bioquímicas e histopatológicas comparando-se o GA com o GC (P<0,05). Com base nos resultados obtidos, é possível inferir uma maior chance de desenvolvimento da obesidade, oriunda do consumo regular desse tipo de adoçante, já que ele comprovou ser capaz de estimular o consumo de alimentos e, consequentemente, o ganho de peso corpóreo.

ABSTRACT Recent years have seen an increase in consumption of diet and light foods by teenagers or those who are looking for a low-calorie diet, thus resulting in several sweeteners such as aspartame. However, their consumption still generates controversy due to many contradictory and inconclusive data. Thus, the aim of this study was to evaluate the effects of aspartame supplementation on dietary intake, physical, biochemical, and histopathological parameters in 18 male Wistar rats, at five weeks old (young mice) treated for 21 days. The animals were randomly assigned into two groups: control group (CG) - treated with distilled water by gavage and aspartame group (GA) - treated with 2ml/100g/day of aspartame. All animals received commercial feed (Essence (r)) and water ad libitum. The control of food intake was recorded weekly. The physical parameters were measured by analyzing the body weight, chest circumference, waist circumference, vertex-coccyx length, total abdominal fat and calculating the body mass index; biochemical parameters were analyzed by glucose, high-density lipoprotein and triglycerides. Apart from such analysis the histopathological study of the liver was conducted. Throughout the experiment the rats treated with aspartame showed a significant increase in body weight and food intake compared to the control group. There was no difference in other analyzes such physical, biochemical, and histopathological comparing GA to GC (P<0.05). From the results we can infer a greater chance of developing obesity, coming from the regular consumption of this type of sweetener, as it proved able to stimulate food intake, and hence the gain of body weight.