Corrigendum: Fat oxidation rates and cardiorespiratory responses during exercise in different subject populations with post-acute sequelae of SARS-CoV-2 infection: a comparison with normative percentile values.

[This corrects the article DOI: 10.3389/fphys.2023.1310319.].

Power output at the moderate-to-heavy intensity transition decreases in a non-linear fashion during prolonged exercise.

PURPOSE: The aims of this study were to: (i) describe the time course of the decrease in power output at the moderate-to-heavy intensity transition during prolonged exercise; (ii) investigate the association between durability of the moderate-to-heavy intensity transition and exercise capacity; and (iii) explore physiological correlates of durability of the moderate-to-heavy intensity transition. METHODS: Twelve trained cyclists (age: 40 ± 8 y, V ˙ O2peak: 52.3 ± 5.2 mL·min-1·kg-1) performed an exhaustive cycling protocol involving alternating incremental exercise tests to determine power output at the moderate-to-heavy intensity transition via the first ventilatory threshold (VT1), and 30-min bouts at 90% of the power output at the previously estimated VT1 in the rested state. The individual time course of VT1 was modelled using linear and second-order polynomial functions, and time to a 5% decrease in VT1 (Δ5%VT1) was estimated using the best-fitting model. RESULTS: Power output at VT1 decreased according to a second-order polynomial function in 11 of 12 participants. Time-to-task failure (234 ± 66 min) was correlated with Δ5%VT1 (139 ± 78 min, rs = 0.676, p = 0.016), and these were strongly correlated with absolute and relative rates of fat oxidation at specific exercise intensities measured during the incremental test performed in the rested state. CONCLUSIONS: These data: (i) identify a non-linear time course of decreases in the moderate-to-heavy intensity transition during prolonged exercise; (ii) support the importance of durability of the moderate-to-heavy intensity transition in prolonged exercise capacity; and (iii) suggest durability of the moderate-to-heavy intensity transition is related to fat oxidation rates.

Muscle-UCP3 in the regulation of energy metabolism.

Uncoupling protein-3 (UCP3) is a mitochondria-regulatory protein with potential energy- homeostatic functions. This study explores the role of UCP3 in the regulation of muscle- and energy metabolism. UCP3 is critical for tuning substrate utilization, favoring lipid oxidation, particularly in conditions of high-fat availability. While UCP3 is non-essential for lipid oxidation during energy excess, it proves vital during fasting, indicating an energy-homeostatic trait. Preliminary evidence indicates UCP3' promotion of glucose uptake and oxidation, at least in conditions of high glucose/low fat availability. However, the dynamics of how fats and glucose differentially influence UCP3 remain undefined. UCP3 exhibits inducible proton transport and uncoupling activity, operating in a dual manner: a resting state with no/low activity and an activated state in the presence of activators. Uncoupling may enhance thermogenesis in specific conditions and in the presence of activators such as fatty acids, thyroid hormones, and catecholamines. This energy-dissipative activity adapts to varying energy availability, balancing energy dissipation with fatty acid oxidation to optimize whole-body energy homeostasis: fasting triggers UCP3 upregulation, enhancing lipid utilization while suppressing uncoupling. Additionally, UCP3 upregulation induces glucose and lipid disposal from the bloodstream and decreases tri-/diglyceride storage in muscle. This process improves mitochondrial functionality and insulin signaling, leading to enhanced systemicgluco-metabolic balance and protection from metabolic conditions. Reviewed evidence suggests that UCP3 plays a crucial role in adapting the system to changing energy conditions. However, the precise role of UCP3 in regulating metabolism requires further elucidation.

The Day-by-Day Periodization Strategies of a Giro d'Italia Podium Finisher.

PURPOSE: The aim of this study was to describe the day-by-day training and racing characteristics in preparation for the Giro d'Italia of 1 world-class road cyclist who achieved a place on the podium in the final general classification of the Giro d'Italia. METHODS: Day-by-day power meter training and racing data of 1 study subject (road cyclist; age 25 y; relative maximum oxygen consumption 81 mL·min-1·kg-1; relative 20-min record power output 6.6 W·kg-1) covering the 152 days leading up to the podium in the Giro d'Italia final general classification were retrospectively analyzed. Daily load, daily volume, and intensity distribution were considered. RESULTS: During training a pattern alternating "hard days" versus "easy days" was observed, as significant amounts of medium or high intensity, or load, were not performed for more than 2 consecutive days This pattern was achieved combining high volume (>4 h) with a significant amount of medium and high intensity within the same training sessions. During training, when training load and intensity increased, the density of "easy days" augmented. In 1-week stage races and the Giro d'Italia, 3 to 8 consecutive days with significant amounts of medium and high intensity were performed. A high number of training sessions with small amounts of medium- and high-intensity volume was observed: 38 days accumulating 3 to 10 minutes at medium intensity and 29 days spending 1 to 9 minutes at high intensity. CONCLUSION: These data provide novel insights about the day-by-day periodization strategies leading to a top 3 in the Giro d'Italia general classification.

Elite Cyclists with Type 1 Diabetes Show Acceptable Glycemic Excursions During a Time-Trial Performance Under High-Definition Transcranial Direct Current Stimulation.

OBJECTIVE: To evaluate the effects of bilateral dorsolateral prefrontal cortex high-definition transcranial direct current stimulation (HD-tDCS) on glycemic excursions during a time-trial performance in elite cyclists with type 1 diabetes (T1D). METHODS: In a double-blind, randomized crossover order, 9 elite cyclists with T1D (no complications) underwent either HD-tDCS (F3 and F4) or control (SHAM) and completed a constant-load trial at 75% of the second ventilatory threshold plus a 15-km cycling time trial. RESULTS: Real-time continuous glucose monitoring revealed similar glycemic variability between the 2 conditions, showing a significant effect of time but no interaction (stimulation × time) or stimulation effect. CONCLUSION: Because glycemic control is crucial for both health and performance, these findings suggest that HD-tDCS could be safely used to enhance performance in athletes with T1D and potentially in a broader active T1D population.

Is change of direction influenced by motor competencies? A possible response from a MOBAK-based study in Italian schoolchildren.

BACKGROUND: Change of direction (COD) ability requires higher motor control capacity and helps children improve individual motor skills. Likewise, basic motor competencies (BMC) are relevant during child maturation and may interleave with COD ability. This study aimed to investigate the possible individual determinants between the COD ability and the BMC, cognitive skills, and anthropometrics characteristics in Italian primary school children aged 6 to 11. METHODS: Children of both sexes (N.=221) were recruited from primary schools (grade 1 to 5) of Northwestern Italy. COD was assessed by 10×5 m Shuttle Run Test; motor coordination by the Motor Coordination (Motorische Basiskompetenzen, MOBAK) 1-6 test battery, whereas Trail Making Test was used to assess cognitive performance. RESULTS: A stepwise linear regression indicated that motor competencies level - assessed by the MOBAK Test - is the most fitting dimension describing COD performance for girls, with the highest R2 in Grade 5 (SEE=0.56); and the lowest SEE in Grade 5 (SEE=1.44); moreover, for boys the highest in Grade 3 (SEE=0.52) and the lowest SEE in Grade 4 (SEE=1.30). CONCLUSIONS: This study confirms the biunivocal relationship between COD and BMC, and the need for physical education teachers and trainers to stimulate both, during growth.

Mental Fatigue Impairs Second Serve Accuracy in Tennis Players.

Purpose: The aim of this 2-week randomized, counterbalance and crossover study was to investigate the effect of acute mental fatigue (MF) on tennis serve performance and accuracy in tennis players. Methods: Ten male tennis players (18 ± 4 years, 1.80 ± 0.08 m; 71 ± 13 kg) were randomized to either the MF group (N = 5) that underwent an acute MF protocol or to a control (CON) group (N = 5). The MF condition consisted in a 30-min modified Stroop color word task performed before on-court serve speed test. A visual analogue scale (VAS) was used to assess the perceptions of MF and motivation toward the upcoming technical tests. Results: Reduction over baseline score of Stroop test was noted in accuracy (N < .001), but not in reaction time (N = .968) in the MF group. Increments in perceived workload were detected (N < .001) in MF group compared to CON. No differences for first and second serve speed from deuce and advantage side were observed. Increment of percentage of failed second serves from the deuce side (N = .043) in MF were detected. Conclusions: An acute MF protocol reduced tennis serve accuracy from deuce side in male tennis players. Players should avoid cognitive efforts before training sessions and matches to prevent negative effects of their technical performance.

Inter-Trial Rest Interval Affects Learning Throwing Skills among Adolescents.

Newly acquired motor skills can be critically driven by different rest periods during practice. Specifically, in the initial stages of motor skill acquisition, the interval between individual trials plays a pivotal role in facilitating effective motor performance, such as in the case of throwing. The objective of this research was to determine the optimal inter-trial rest period promoting efficient motor performance, focusing on two specific motor task actions. In a randomized counterbalanced cross-over research design 169 high-school students aged 14 were studied (M = 150; F = 19). In one block, participants performed 10 basketball free throws with a short rest interval (< 5 s) and 10 other throws with a long rest interval (∼50-60 s). In a second block, they threw a regular size tennis ball into a 1-m diameter circle on the floor at 6.75 m, again throwing 10 times with a short inter-trial rest interval and 10 times with a long inter-trial rest interval. The order of the rest intervals within each block was randomized and counterbalanced. With a repeated measures two-way analysis of variance, greater accuracy seemed to be associated with short intra-set rest intervals as there were significant main effects of both conditions (F1,167 = 368.0, p < 0.001, η2p = 0.271) and resting time (F1,167 = 18.6, p < 0.001, η2p = 0.192) and no significant interaction "condition by time". Fast practice was efficient independently of the complexity of the throwing task, suggesting robust support for schema theory.

Fat oxidation rates and cardiorespiratory responses during exercise in different subject populations with post-acute sequelae of SARS-CoV-2 infection: a comparison with normative percentile values.

Introduction: Post-acute sequelae of SARS-CoV-2 infection (PASC) presents a spectrum of symptoms following acute COVID-19, with exercise intolerance being a prevalent manifestation likely linked to disrupted oxygen metabolism and mitochondrial function. This study aims to assess maximal fat oxidation (MFO) and exercise intensity at MFO (FATmax) in distinct PASC subject groups and compare these findings with normative data. Methods: Eight male subjects with PASC were involved in this study. The participants were divided into two groups: "endurance-trained" subjects (V˙O2max > 55 mL/min/kg) and "recreationally active" subjects (V˙O2max < 55 mL/min/kg). Each subject performed a graded exercise test until maximal oxygen consumption (V˙O2max) to measure fat oxidation. Subsequently, MFO was assessed, and FATmax was calculated as the ratio between V˙O2 at MFO and V˙O2 max. Results: The MFO and FATmax of "endurance-trained" subjects were 0.85, 0.89, 0.71, and 0.42 and 68%, 69%, 64%, and 53%, respectively. Three out of four subjects showed both MFO and FATmax values placed over the 80th percentile of normative data. The MFO and FATmax of "recreationally active" subjects were 0.34, 0.27, 0.35, and 0.38 and 47%, 39%, 43%, and 41%, respectively. All MFO and FATmax values of those subjects placed below the 20th percentile or between the 20th and 40th percentile. Discussion: Significant differences in MFO and FATmax values between 'endurance-trained' and "recreationally active" subjects suggest that specific endurance training, rather than simply an active lifestyle, may provide protective effects against alterations in mitochondrial function during exercise in subjects with PASC.

"I RUN CLEAN Project"-An Innovative and Self-Sustainable Approach to Develop Clean Sport Behaviours in Grassroots Athletes.

The phenomenon of doping is a public health issue that poses threats to sport and society. In recent decades, the emphasis on efforts to address the issue and reduce the incidence of doping by young people in sport has shifted from deterrence through testing and punishment to the promotion of clean sport behaviours through values-based education. The "I Run Clean project" sought to develop new and effective tools targeting grassroots athletes and those around them (coaches, medical support personnel, sport leaders, parents). These included sport-specific e-learning and in-person peer-to-peer workshops led by trained volunteer ambassadors. The aim of all "I Run Clean" measures is to go beyond the warnings and provision of factual information about early anti-doping campaigns to a more holistic educational approach that focuses participants on their personal and sport-related values in order to encourage good decision-making and resistance to doping-related behaviours. This study evaluates the efficacy of the peer-to-peer workshops and their impact on selected psycho-social variables. The collaboration of the volunteer ambassadors is shown to effectively transmit the desired reasoning, reduce doping risk factors and enhance protective factors.

"I Am on Top!": An Interactive Intervention Program to Promote Self-Regulation Processes in the Prevention of the Use of Doping in Sports High Schools.

The use of substances to improve sports performance is a widespread phenomenon among adolescents. Several anti-doping programs have been developed, mainly based on knowledge-based evidence. The main aim of the present study was to implement an anti-doping intervention in sports high school students, based on a psychological framework, such as Socio-Cognitive Theory, through the development of a Serious Game (SG), i.e., digital learning based on the game. The experimental design included an intervention group (n = 167; F = 37.7%; Meanage = 17.5 years; SD = 0.58) and a control group (n = 112; F = 42%; Meanage = 17.6; SD = 1). Both of the groups completed the same questionnaire on two different occasions (i.e., time 1 and time 2) for measuring doping intention, self-regulatory efficacy to resist social pressure for the use of substances, moral disengagement, and doping knowledge. Data were analyzed through repeated measures of Group X Time ANOVA, demonstrating some degree of efficacy of the intervention, in particular in terms of the decrease in doping intention and the strengthening of doping knowledge. Moreover, the study demonstrated that the score obtained during the implementation of the SG could partially represent a coherent measure of the participants' beliefs regarding doping. These results could be considered a starting point for future research to better develop technological anti-doping interventions.

Partial-body cryostimulation procured performance and perceptual improvements in amateur middle-distance runners.

The purpose of this study was to investigate the effects of partial-body cryostimulation on middle-distance runners before two 3000-m tests at the speed of the first and second ventilatory threshold, and before a time to exhaustion test at 110% of the maximal aerobic speed. Twelve amateur runners (age: 46 ± 9 years; VO2max: 51.7 ± 4.9 ml·kg-1·min-1) completed six running testing sessions in a randomized counterbalanced cross-over fashion: three of them were preceded by a partial-body cryostimulation and the other three by a control condition. The testing sessions consisted of: 1) a 3000-m continuous running test at the speed of the first ventilatory threshold; 2) a 3000-m continuous running test at the speed of the second ventilatory threshold; 3) a time to exhaustion test at 110% of the maximal aerobic speed. Heart rate, ratings of perceived exertion and visual analogue scale relative to muscle pain were recorded throughout the tests. Total quality recovery was evaluated 24-48 h after the end of each test. Distance to exhaustion was higher after partial-body cryostimulation than control condition (p = 0.018; partial-body cryostimulation: 988 ± 332 m, control: 893 ± 311 m). There were differences in the ratings of perceived exertion during each split of the 3000-m continuous running test at the speed of the second ventilatory threshold (p = 0.001). Partial-body cryostimulation can be positively considered to enhance middle-distance running performance and reduce perception of effort in amateur runners.

Do maturation, anthropometrics and leg muscle qualities influence repeated change of direction performance in adolescent boys and girls?

The ability to change direction rapidly is a key fitness quality especially in invasive sports where young players perform approximately 300 changes of direction in a game. There is currently limited understanding of how anthropometric characteristics and maturation status influence change of direction ability in adolescent. Therefore, the purpose of this investigation is to assess the influence of anthropometrics and maturation status on change of direction ability in young people. The study involved 706 adolescents (367 girls) aged 14-19-year-old attending the same high school in Northern Italy. Stature, body mass, seated height and leg length were measured to determine the anthropometrics and maturation status of the participants. Repeated change of direction ability (10 × 5 m shuttle run test), lower limb power and muscle strength were evaluated using field tests from the Eurofit test battery. Maturity offset was calculated separately for boys and girls, in accord with the equation proposed by Mirwald. Preliminary analysis with 10 × 5 m as a dependent variable and sex and PHV as a fixed factor, suggests a significant difference between sex (p < 0.001; d = 0.35) but not with PHV (p = 0.986; d = 0.000) and interaction PHV × sex (p = 0.836; d = 0.000). Our results suggested that repeated change of direction performance was influenced by anthropometrics, maturation and muscle qualities in adolescent boys and girls.

The Weekly Periodization of Top 5 Tour de France General Classification Finishers: A Multiple Case Study.

PURPOSE: The aim of this study was to describe individual training characteristics, racing strategies, and periodization in preparation for the Tour de France in 2 world-class road cyclists finishing in the top 5 of the general classification. METHODS: Week-by-week power meter training and racing data of 2 (A and B) road cyclists (age: 29 and 23 y; maximum oxygen consumption: 83 and 81 mL·min-1·kg-1; and relative 20-min record power output: 6.9 and 6.5 W·kg-1) in the preparation phase (December-July/August) leading up to the Tour de France were retrospectively analyzed. Weekly volume and intensity distribution in power zones were considered. RESULTS: Cyclists A and B completed 46 and 19 races, 22.5 (6.3) and 18.2 (5.1) h·wk-1, with a pyramidal intensity distribution of 81.0%-13.3%-5.7%, and 88.8%-7.9%-3.3% in zone 1-zone 2-zone 3. Cyclist B spent 14 days at altitude. Increased high-intensity volume and polarization index occurred during race weeks. During periods without racing, training intensity progressively increased. Strength training was performed during November and December but not during the following months. During tapering, total exercise volume and time at high intensity decreased. CONCLUSION: These data provide novel insights into the periodization of world-class road cyclists in advance of a top 5 placing in the Tour de France general classification.

Antihistamines improve cardiovascular manifestations and other symptoms of long-COVID attributed to mast cell activation.

Introduction: Long-COVID is a broadly defined condition and there are no effective therapies. Cardiovascular manifestations of long-COVID include high heart rate, postural tachycardia, and palpitations. Previous studies have suggested that mast cell activation (MCA) may play a role in the pathophysiology of long-COVID, including in the mechanisms of its cardiovascular manifestations. The present study aimed to evaluate the effectiveness of a treatment with blockers of histamine receptors in patients with long-COVID who did not respond to other therapies. Methods: In all, 14 patients (F/M = 9/5; 49.5 ± 11.5 years) and 13 controls (F/M = 8/5; 47.3 ± 8.0 years) with long-COVID symptoms attributed to MCA were evaluated. Patients were treated with fexofenadine (180 mg/day) and famotidine (40 mg/day). Fatigue, brain fog, abdominal disorders, and increased heart rate were evaluated in treated and untreated patients at baseline and 20 days later. Results: Long-COVID symptoms disappeared completely in 29% of treated patients. There was a significant improvement in each of the considered symptoms (improved or disappeared) in all treated patients, and the improvement grade was significantly greater in treated patients compared to controls. No significant differences in the outcomes were observed in the controls. Conclusions: Our data confirm that histamine receptors blockade may be an effective target to successfully treat long-COVID. Our finding supports the underlying role of MCA in the pathophysiology of long-COVID.

Thermal responses induced by nitrogen and forced convection based partial-body cryostimulation.

Partial Body Cryostimulation (PBC) involves a very cold air flow directed to the body of subjects with minimal clothing. PBC is performed in a rapid timeframe, inside an on-purposed designed cryo-cabin. Recently, cryo-cabins have been built with different energy systems, however a validation study on relative thermal responses is missing. This study was aimed at comparing thermal responses following a PBC in an electrically powered cryo-cabin based on forced convection or into a standard nitrogen-fueled cryo-cabin. In a randomized crossover fashion, thirty-six subjects (F=20; M=16) underwent both cryo-exposures lasting 150 s each. Thermal responses were assessed before and immediately after completing each PBC session. Mixed model analysis of variance revealed a significantly colder temperature after electric PBC in all the body regions (except for the thighs) with respect to a standard nitrogen based PBC (F: 16.4 ± 1.4 vs 18 ± 5.8 °C; M: 16.4 ± 1.7 vs 20.9 ± 4 °C). Moreover, a significant lower thermal discomfort was perceived at the end of electric PBC as compared to that one felt following standard PBC. For the first time, the safety and thermo-effectiveness of an electric cryo-cabin based on forced convection was ensured. This methodology can be viable for practitioners of PBC and clinicians.

Exercise Restores Hypothalamic Health in Obesity by Reshaping the Inflammatory Network.

Obesity and overnutrition induce inflammation, leptin-, and insulin resistance in the hypothalamus. The mediobasal hypothalamus responds to exercise enabling critical adaptions at molecular and cellular level that positively impact local inflammation. This review discusses the positive effect of exercise on obesity-induced hypothalamic dysfunction, highlighting the mechanistic aspects related to the anti-inflammatory effects of exercise. In HFD-fed animals, both acute and chronic moderate-intensity exercise mitigate microgliosis and lower inflammation in the arcuate nucleus (ARC). Notably, this associates with restored leptin sensitivity and lower food intake. Exercise-induced cytokines IL-6 and IL-10 mediate part of these positive effect on the ARC in obese animals. The reduction of obesity-associated pro-inflammatory mediators (e.g., FFAs, TNFα, resistin, and AGEs), and the improvement in the gut-brain axis represent alternative paths through which regular exercise can mitigate hypothalamic inflammation. These findings suggest that the regular practice of exercise can restore a proper functionality in the hypothalamus in obesity. Further analysis investigating the crosstalk muscle-hypothalamus would help toward a deeper comprehension of the subject.

Physical Inactivity and Depression: The Gloomy Dual with Rising Costs in a Large-Scale Emergency.

At the end of October of 2022, the World Health Organization (WHO) released "the Global status report on physical activity 2022" [...].

Overexpression of UCP3 decreases mitochondrial efficiency in mouse skeletal muscle in vivo.

Uncoupling protein-3 (UCP3) is a mitochondrial transmembrane protein highly expressed in the muscle that has been implicated in regulating the efficiency of mitochondrial oxidative phosphorylation. Increasing UCP3 expression in skeletal muscle enhances proton leak across the inner mitochondrial membrane and increases oxygen consumption in isolated mitochondria, but its precise function in vivo has yet to be fully elucidated. To examine whether muscle-specific overexpression of UCP3 modulates muscle mitochondrial oxidation in vivo, rates of ATP synthesis were assessed by 31 P magnetic resonance spectroscopy (MRS), and rates of mitochondrial oxidative metabolism were measured by assessing the rate of [2-13 C]acetate incorporation into muscle [4-13 C]-, [3-13 C]-glutamate, and [4-13 C]-glutamine by high-resolution 13 C/1 H MRS. Using this approach, we found that the overexpression of UCP3 in skeletal muscle was accompanied by increased muscle mitochondrial inefficiency in vivo as reflected by a 42% reduction in the ratio of ATP synthesis to mitochondrial oxidation.