Romulo Bertuzzi

Ozone (O ₃ ) is a photochemical air pollutant known to reduce lung function and induce respiratory symptoms. This study aimed to determine whether breathing route influences O ₃ ‐induced lung function changes during exercise. Thirteen recreationally active participants (6 females, V̇O ₂ peak = 45.8 ± 5.3 mL/kg/min), with no history of cardiovascular or pulmonary disease or exercise‐induced bronchoconstriction, completed a double‐blind crossover study with four experimental visits. Participants performed 30 min of low‐intensity cycling (90% of power at the first ventilatory threshold) while breathing exclusively nasally or orally under room air or 0.40 ppm O ₃ . Spirometry was assessed before and after each trial, and dyspnea (Multidimensional Dyspnea Profile) every 5 min during exercise. O ₃ exposure impaired pulmonary function, reducing FEV ₁ , FVC, PEF, FEF25–75, and FEV ₁ /FVC (all p < 0.05). Regardless of environmental condition, oral breathing produced modestly greater post‐exercise reductions in FEV ₁ , PEF, FEF25–75, and FEV ₁ /FVC than nasal breathing, but no breathing route × environment interaction was observed. Nasal breathing was associated with greater breathing effort and air hunger ( p < 0.05). Thus, O ₃ exposure impaired pulmonary function and increased dyspnea regardless of breathing route. Although nasal breathing slightly attenuated overall post‐exercise lung function decline, it did not protect against O ₃ ‐induced pulmonary impairment and increased breathing discomfort during exercise.

This randomized, placebo-controlled trial investigated the effects of acute metformin ingestion on energy system contributions during high-intensity endurance exercise. Ten recreationally active males (VO2max: 38.6 ± 4.5 mL·kg−1·min−1) completed an incremental cycling test to determine VO2max and maximal workload (Wmax). Using a crossover design, participants performed an exhaustive cycling effort at 110% Wmax one hour after ingesting 500 mg of metformin or placebo. Energy system contributions (aerobic, anaerobic alactic, anaerobic lactic) were estimated using GEDAE-LaB software, based on VO2 and blood lactate kinetics. Total energy expenditure did not significantly differ between conditions (metformin: 165.6 ± 26.3 kJ; placebo: 155.7 ± 30.5 kJ; P = 0.09). The aerobic contribution was significantly greater following metformin ingestion (108.4 ± 25.2 vs. 94.0 ± 25.8 kJ; P < 0.01), however, anaerobic energy contributions were not affected (alactic: 33.3 ± 8.7 vs. 36.5 ± 14.3 kJ, P = 0.37; lactic: 24.0 ± 8.8 vs. 25.3 ± 9.4 kJ, P = 0.62). Acute metformin ingestion increases the aerobic energy contribution during high-intensity endurance exercise without impairing anaerobic energy systems.

The mechanisms underlying fatigue during prolonged exercise remain a topic of ongoing debate. A recent review by Noakes et al. proposes that exercise-induced hypoglycemia, rather than skeletal muscle glycogen depletion, is a primary determinant of exercise termination, and that prolonged exercise is interrupted by centrally mediated protective mechanism to ensure that fatal neuroglycopenia does not develop. By reanalyzing studies reporting blood glucose at exhaustion, we highlight that, in the absence of carbohydrate (CHO) ingestion, exercise termination consistently coincides with clinically relevant hypoglycemia, supporting the suggestion that low levels of blood glucose operate as an important afferent signal to the brain. However, when CHO is periodically ingested during exercise, exercise termination occurs despite the maintenance of blood glucose within near-resting levels. Thus, blood glucose concentration may no longer represent the dominant afferent signal contributing to exercise termination when CHO is ingested. Instead, other physiological constraints, such as thermal and cardiovascular strain and peripheral muscle perturbations may become increasingly relevant as exercise is prolonged by CHO ingestion. A deeper understanding of how multiple afferent signals interact to regulate muscle recruitment during prolonged exercise may provide new insights for both exercise physiology and sports nutrition. While the recent review of Noakes et al. represents a major advancement toward redefining the role of blood glucose in exercise capacity, it also opens a compelling avenue for future research to clarify the primary limiting factors when prolonged exercise is terminated in the absence of hypoglycemia.

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). PM_2.5 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.

In this study, we showed that females and males develop a similar hypoxia-induced impairment in endurance performance, perceived and performance fatigability during a 4-km cycling time trial. These novel findings indicate that females and males regulate their power output similarly during a 4-km cycling time trial under moderate hypoxia, likely to avoid prematurely exacerbating metabolic disturbances and thereby reaching comparable levels of performance fatigability by the end of the task.

We have previously demonstrated that different modalities of endurance exercise combined with lower muscle glycogen content elicit several physiological and molecular benefits in men. In this study, we hypothesized that these exercise strategies modulate monocarboxylate transporters (MCTs) and plasma lactate. We investigated MCT1 and MCT4 gene expression after two forms of exercise (i.e., once daily and twice-a-day) under low carbohydrate (CHO) availability (Acute - Study 1) and whether three weeks under once daily or twice-a-day training differentially affected plasma lactate during exercise (Chronic - Study 2). In Study 1, five participants performed a high-intensity interval exercise (HIIE) 2 h (twice-a-day) or 15 h (once daily) after exercise and diet manipulations to reduce endogenous CHO stores or without previous CHO manipulation (Control). Muscle biopsies were collected before, right after, and 3 h after HIIE. In Study 2, plasma lactate was measured during a graded exercise test before and after three weeks of once-daily (n=7) or twice-a-day training (n=7). MCT1 gene expression increased from before to after and 3-h post-HIIE only in the twice-a-day exercise (P0.05). The plasma lactate curve shifted to the right in both training approaches, without differences in lactate slope reduction between once-daily (-0.49±0.58 mmol·L-1·min-1) and twice-a-day (-0.46±0.73 mmol·L-1·min-1) exercise. In conclusion, twice-a-day training increased acute MCT1 gene expression but did not result in chronic changes in plasma lactate response during exercise.

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.

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 (Ptw_pot) 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). Ptw_pot of knee extensors decreased from prematch 1 to postmatch 1 (P < .001) and remained reduced until postmatch 4 (P < .001). Ptw_pot 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 Ptw_pot 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.

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.