Fundamentals of glycogen metabolism for coaches and athletes

Impact of carbohydrate timing on glucose metabolism and substrate oxidation following high-intensity evening aerobic exercise in athletes: a randomized controlled study

OBJECTIVE

The study aimed to investigate the impact of nutrient timing in relation to evening exercise. Specifically, it examined the effects of pre- or post-exercise carbohydrate (CHO) ingestion on glucose metabolism, glucose regulation, and overall substrate oxidation in well-trained athletes during and after physical exercise (PE), spanning the nocturnal period and the subsequent morning.

METHODS

Ten male endurance cyclists participated in the study. The initial assessments included body composition measurements and an incremental cycle test to determine maximal oxygen uptake (V ˙ O2 max) and maximum power output (Wmax). Following this, participants underwent a control (rest previous day) oral glucose tolerance test (OGTT) and a familiarization exercise trial that had two objectives: (1) to establish the appropriate amount of CHO to use in the pre- or post-exercise drink during the experimental trials, and (2) to familiarize participants with the equipment and study protocol. In the three days prior to both the control and experimental trials, participants followed a standardized, individualized diet designed to meet their energy needs. During the experimental trials, participants completed two separate evening exercise sessions (50 min@70%Wmax +  ~24 min time-trial (TT)) with either pre- or post-exercise CHO ingestion (253 ± 52 g), matching the CHO oxidized during exercise. The CHO drink and a volume-matched placebo (PLA) drink (containing no energy) were randomly assigned to be consumed two hours before and directly after the experimental exercise sessions. Post-exercise nocturnal interstitial glucose levels (24:00-06:00) were continuously monitored, and a 120-min OGTT was conducted the following morning to assess substrate oxidation rates and glucose control.

RESULTS

Pre-exercise CHO intake significantly lowered capillary glucose levels during steady-state exercise (mean difference 0.41 ± 0.27 mmol/L, p = 0.001) without affecting perceived exertion and TT-performance. No difference was observed in nocturnal glucose regulation (00:00-06:00) regardless of whether CHO was consumed before or after exercise. Post-exercise CHO ingestion reduced glucose tolerance during the OGTT compared to the iso-caloric pre-exercise CHO intake (mean difference 0.76 ± 0.21 mmol/L, p = 0.017). However, a post-exercise CHO intake improved respiratory exchange ratio/metabolic flexibility (MetF) significantly. Enhanced MetF during the first OGTT hour after post-exercise CHO ingestion resulted in 70% and 91% higher CHO oxidation compared to pre-exercise CHO and control, respectively (p ≤ 0.029). Average 120-min OGTT fat oxidation rates were higher with both pre- and post-exercise CHO ingestion compared to control (p ≤ 0.008), with no difference between pre- and post-exercise CHO intake.

CONCLUSION

Morning glucose tolerance was markedly reduced in healthy athletes when CHO was ingested after evening exercise. However, the observed improvements in MetF during the OGTT compared to placebo post-exercise suggest a potential for enhanced athletic performance in subsequent exercise sessions. This opens exciting possibilities for future research to explore whether enhanced MetF induced by CHO-timing can translate to improved athletic performance, offering new avenues for optimizing training and performance.

International society of sports nutrition position stand: nutrition and weight cut strategies for mixed martial arts and other combat sports

Following an extensive literature review, the International Society of Sports Nutrition (ISSN) has developed an official position on nutritional and weight cut strategies for combat sports. The type of combat sport, length of the fight camp, and time between weigh-in and competition are factors influencing nutritional and weight cut strategies. The following 16 points constitute the Position Statement of the Society; the Research Committee has approved them. 1. Combat sports have differing weight categories, official weigh-in times, and competition frequencies, influencing the nutritional and weight cut strategies for training and competition. 2. As the duration of a combat match increases, >4 min, contribution of the aerobic system can rise to >70%, yet anaerobic alactic pathways and anaerobic glycolytic pathways support high-output bursts. 3. During the off camp/general preparation phase, athletes should maintain a weight ranging 12% to 15% above the weight division requirement. 4. Supplements including creatine, beta-alanine, beta-hydroxy-beta-methylbutyrate, and caffeine have been shown to enhance performance and/or recovery during preparation phases, competition, and post-competition. 5. During fight camp, strategic decreases in calorie intake are necessary for an efficient longitudinal weight descent. Individual caloric needs can be determined using indirect calorimetry or validated equations such as Mifflin St. Jeor or Cunningham. 6. Protein should be prioritized during longitudinal weight descents to preserve lean body mass, and the timely delivery of carbohydrates supports training demands. Macronutrients should not drop below the following: carbohydrates 3.0-4.0 g/kg, protein 1.2-2.0 g/kg, and fat 0.5 to 1.0 g/kg/day. 7. Suitable losses in body mass range from 6.7% at 72 h, 5.7% at 48 h, and 4.4% at 24 h, prior to weigh-in. 8. Sodium restriction and water loading are effective for inducing polyuria and acute water loss. 9. During fight week, water-bound glycogen stores can be depleted through exercise and carbohydrate restriction, facilitating a 1% to 2% loss in body mass, with equivalent losses from a low-fiber intake of <10 g/day for 4 days. 10. During fight week, acute water loss strategies, including sauna, hot water immersion, and mummy wraps, can be used effectively with appropriate supervision (optimally ~2-4% of body mass within 24 h of weigh-in). 11. Post-weigh-in, rapid weight gain strategies are utilized to recover lost body fluid/mass before competition with the intent of gaining a competitive advantage. 12. Oral rehydration solutions (1 to 1.5 liters/h) combined with a sodium range of 50-90 mmol/dL should take precedence immediately post-weigh-in. 13. Fast-acting carbohydrates at a tolerable rate of ≤ 60 g/h should follow oral rehydration solutions. Post weigh-in intake of fiber should be limited to avoid gastrointestinal distress. 14. Post-weigh-in carbohydrate intake at 8-12 g/kg may be appropriate for combat athletes that undertook significant glycogen depletion strategies during fight week. About 4-7 g/kg may be suitable for modest carbohydrate restriction. 15. Post weigh-in, rehydration/refueling protocols should aim to regain ≥10% of body mass to mitigate declines in performance and the negative effects of rapid weight loss. 16. The long-term effects of frequent weight cuts on health and performance are unknown, necessitating further research.

Elite collegiate swimmers do not meet sport nutrition recommendations during heavy training: effects of sex and within-day nutrient timing

BACKGROUND

Compared to the general population, athletes experience high energy expenditures requiring increased energy and macronutrient intakes to sustain training and optimize performance. While the International Olympic Committee (IOC) and International Society for Sports Nutrition (ISSN) have established recommendations for nutrient intakes, many athletes do not meet the recommended daily allowance (RDA) for the general population, and sport and sex-specific differences are not well documented. Exploration of within-day energy balance (WDEB) shows athletes may achieve energy balance by the end of the day but may present with poor WDEB. Data support that female athletes are at greater risk of nutrient deficiencies than their male counterparts, and it is unclear whether swimmers meet sport-specific nutrient intake and timing recommendations. Following our previous WDEB analysis, the purpose of this investigation was to assess dietary macronutrient intake as related to RDAs (USDA and IOC/ISSN), within-day macronutrient timing, and associated sex differences in swimmers.

METHODS

In elite male and female swimmers (n = 25; 18-22 yr), we assessed energy intake (EI), total daily energy expenditure (TDEE), macronutrient intake (fat (FAT), protein (PRO), carbohydrate (CHO)) and timing during heavy training. Frequency analysis was utilized to determine the number of athletes meeting general and athlete-specific RDAs. Repeated-measures ANOVA was used to assess nutrient timing across sex groups.

RESULTS

When compared to IOC/ISSN daily recommendations, only 6/25 swimmers met FAT intake, 7/25 met CHO intake, and 24/25 met PRO intake IOC/ISSN daily recommendations.Males had greater EI and TDEE compared to females (p < 0.05). PRO consumption (% of EI) was a larger percentage of total intake in male vs females (28 ± 5% vs 23 ± 3%; F = 2.996; p = 0.014). No swimmers met CHO recommendations (g⋅kg-1) pre- or during exercise for the first daily training session. 13/25 met pre-exercise CHO recommendations, while 6/25 and 11/25 met during and post-exercise CHO recommendations for the second training session. Repeated measures ANOVA revealed effects of sex and time on intake (g⋅kg LBM-1⋅hr-1) for FAT (Sex; F = 5.659, p = 0.26; time; F = 12.068, p = 0.006) and PRO (Sex; F = 6.719, p = 0.016; time; F = 13.177, p = 0.011). There was a significant sex*time interaction for CHO consumption (F = 6.520, p = 0.017).

CONCLUSION

The results from this study demonstrate significant sex-differences, indicating that most swimmers meet athlete-specific recommendations for PRO, but not CHO or FAT intake. CHO timing for pre-, during, and post-exercise was met by only 52% swimmers. Results suggest that swimmers should prioritize CHO intake, emphasized around and during training bouts.

Carbohydrate ingestion during prolonged exercise blunts the reduction in power output at the moderate-to-heavy intensity transition

PURPOSE

To determine the effect of carbohydrate ingestion during prolonged exercise on durability of the moderate-to-heavy-intensity transition and severe-intensity performance.

METHODS

Twelve trained cyclists and triathletes (10 males, 2 females;V ˙ O 2 peak, 59 ± 5 mL kg-1 min-1; training volume, 14 ± 5 h week-1) performed an incremental test and 5-min time trial (TT) without prior exercise (PRE), and after 150 min of moderate-intensity cycling, with (POSTCHO) and without (POSTCON) carbohydrate ingestion.

RESULTS

Power output at the first ventilatory threshold (VT1) was lower in POSTCHO (225 ± 36 W, ∆ -3 ± 2%, P = 0.027, n = 11) and POSTCON (216 ± 35 W, ∆ -6 ± 4%, P = 0.001, n = 12) than PRE (229 ± 37 W, n = 12), and lower in POSTCON than POSTCHO (∆ -7 ± 9 W, ∆ -3 ± 4%, P = 0.019). Mean power output in the 5-min TT was lower in POSTCHO (351 ± 53 W, ∆ -4 ± 3%, P = 0.025) and POSTCON (328 ± 63 W, ∆ -10 ± 10%, P = 0.027) than PRE (363 ± 55 W), but POSTCHO and POSTCON were not significantly different (∆ 25 ± 37 W, ∆ 9 ± 13%, P = 0.186). Blood glucose concentration was maintained in POSTCHO, and was significantly lower at the 120 and 150-min timepoint in POSTCON (P < 0.05).

CONCLUSION

These data suggest that durability of the moderate-to-heavy-intensity transition is improved with carbohydrate ingestion. This has implications for training programming and load monitoring.

Nutritional Strategies to Improve Post-exercise Recovery and Subsequent Exercise Performance: A Narrative Review

Post-exercise recovery strategies influence the body's ability to restore physiological homeostasis, replenish energy stores, repair muscle damage, and promote desired adaptations, which improve exercise performance. This narrative review examines the impact of nutritional strategies commonly used for enhancing recovery and subsequent exercise performance, particularly when athletes face short recovery periods. Carbohydrate ingestion is essential for glycogen replenishment, especially within the initial hours post-exercise, with its impact dependent on the types, timing, and amount. Protein is essential for accelerating muscle recovery and achieving a positive nitrogen balance, depending on the type and dosage. The co-ingestion of carbohydrates with proteins or fats is explored for its role in maximizing glycogen resynthesis and muscle repair, with evidence supporting the addition of protein to suboptimal carbohydrate intake for enhanced recovery. Moreover, this review addresses the potential benefits of creatine and caffeine co-ingestion for accelerating glycogen synthesis and improving subsequent performance. Hydration strategies, including the use of milk-based beverages and electrolyte solutions, are also discussed, emphasizing their importance in maintaining fluid balance and optimizing recovery. This review also highlights the emerging role of micronutrients such as omega-3 fatty acids, antioxidants, and sodium bicarbonate in reducing muscle damage and improving acid-base balance. Evidence supports the tailored use of these nutritional strategies, particularly for athletes managing tight competition/training schedules. Future research should focus on refining individualized approaches for recovery and investigating the impact of novel supplements on subsequent performance.

Nutritional Intake and Timing of Marathon Runners: Influence of Athlete's Characteristics and Fueling Practices on Finishing Time

BACKGROUND

Endurance athletes' competitions have increased over the decades and marathon races are becoming increasingly popular. Proper nutrition is critical for optimal performance and long-term health in marathon athletes. This study aimed to investigate runners' nutritional intake, especially fluids, food, and supplements, competing in the Seville Marathon. A descriptive and cross-sectional study was carried out to obtain information on the consumption of liquids, food, and supplements. A total of 160 runners (aged 42.2 ± 7.3 years) who were primarily men (87.5%) who participated in the 2022 Seville marathon took part in the study.

RESULTS

There was no significant difference (p > 0.050) between marathon finish time (from 2 h 12 min to 5 h) or sports experience and fluid, carbohydrates (CHO), sodium, and caffeine intake pre- and post-competition. However, according to the results obtained, the athletes who met CHO intake recommendations during the competition (60-90 g/h) were more likely to finish the marathon in less than 180 min (p = 0.035).

CONCLUSIONS

The intake of CHO (35 ± 17 g/h), sodium (192 ± 150 mg/h) and caffeine (57 ± 49 mg/h) was low compared to the current recommendations during the competition. The intake of fluids (466 ± 279 mL/h) was at the lower limit of recommendations. Most athletes did not receive nutritional counselling by a sport dietitian, which may explain why athletes failed to meet specific nutrient recommendations. Future investigations with a larger sample size are warranted to assess the relationship between dietary intake and finish time.

A Review of Carbohydrate Supplementation Approaches and Strategies for Optimizing Performance in Elite Long-Distance Endurance

Carbohydrate supplementation is a common practice among endurance athletes participating in long-distance competitions. However, glycogen storage regulation, in-competition blood glucose levels, and their relationship with athletic performance are influenced by multiple factors. This review summarizes the recent research progress on carbohydrate supplementation, addressing its applications in the pre-, during-, and post-competition phases. It explores variables that influence the effectiveness of carbohydrate supplementation and provides a summary of strategies, based on six key aspects: carbohydrate properties, multi-nutrient interactions, gastrointestinal function, individual differences (such as age and gender), environmental conditions, and psychological factors. The combination of different types, ratios, and concentrations of carbohydrates has been demonstrated to enhance the efficiency of carbohydrate digestion and absorption. The synergistic combination of protein, sodium, and caffeine intake demonstrates enhanced efficacy in carbohydrate supplementation strategies. Gastrointestinal tolerance training for carbohydrate supplementation has been identified as an effective measure to alleviate gastrointestinal discomfort during high-dose carbohydrate intake. The adjustment of the carbohydrate-to-fat ratio and the type of carbohydrate intake has been found to mitigate the impact of gender and menstrual cycles on glycogen storage and substrate utilization. Modifying the timing of glycogen storage and regulating the concentration and temperature of carbohydrate solutions during competition have been demonstrated to facilitate coping with the elevated energy expenditure and metabolic substrate shift from fat to carbohydrates, triggered by a combination of environmental and psychological factors, including special environmental and climatic conditions (e.g., high altitude, high temperature, high humidity, and cold) and emotional states (e.g., pre-competition stress and anxiety during the competition). To achieve precise carbohydrate supplementation for athletes in major events under various competitive environments, it is necessary to quantitatively assess the effects of carbohydrate supplementation, supported by mechanistic studies. This can be achieved by utilizing wearable devices to monitor the entire competition, coupled with data collection technologies, such as high-throughput profiling. Furthermore, emerging data analytics techniques, such as machine learning and causal inference, should be leveraged to refine supplementation strategies.

Intermittent fasting versus continuous caloric restriction for glycemic control and weight loss in type 2 diabetes: A traditional review

Type 2 Diabetes Mellitus (T2DM) represents a major global health issue, with its incidence anticipated to increase markedly in the forthcoming decades. Efficient non-pharmacological therapies, especially dietary approaches, are essential for regulating glycemic control and facilitating weight reduction. Intermittent Fasting (IF) and Continuous Caloric Restriction (CCR) are two well researched methodologies, but their relative effectiveness and enduring advantages continue to be topics of active discussion. This review systematically assesses and contrasts the impacts of intermittent fasting (IF) and continuous calorie restriction (CCR) on glycemic regulation and weight reduction in persons with type 2 diabetes mellitus (T2DM), highlighting their short-term and long-term effects, safety profiles, and adherence rates. A thorough literature analysis was performed utilizing PubMed and Google Scholar, concentrating on papers published from 2000 to 2024. The review encompassed randomized controlled trials and observational studies that investigated the effects of intermittent fasting (IF) and continuous calorie restriction (CCR) on glycemic indicators (HbA1c, fasting glucose) and body weight. IF shown substantial short-term advantages, encompassing marked decreases in HbA1c levels, fasting glucose, and body weight. Mechanistic discoveries emphasized better insulin sensitivity, augmented fat metabolism, and autophagy as key aspects. In contrast, CCR was linked to enduring metabolic enhancements, including decreased visceral fat and improved insulin sensitivity. Nevertheless, both dietary approaches demonstrated constraints.

Energy and Key Micronutrient Intake in Amateur Swimmers: A Pilot Study

Swimming is a highly demanding sport that requires the integration of multiple physical, physiological, and psychological factors for optimal performance. Despite its popularity, most swimmers are amateur, and few studies have assessed energy and nutrient intake at this athlete level. Therefore, the aim of the present pilot study was to evaluate energy and nutrient intake and compare them with the recommended values. Methods: The participants were recruited from local teams. To determine body composition, weight, height, and skinfold measurements were taken. Food intake assessment was conducted through a 3-day food log. Results: The sample was composed of 15 individuals, where 7 were female. There were no significant differences in energy and macronutrient intake between male and female swimmers, nor between rest or workout days. Despite protein intake being within the recommendation, the estimated average intake for energy was significantly lower than the recommended values. Female swimmers also showed an inadequate intake of calcium, iron, and zinc. Conclusions: Swimmers showed an inadequate energy and carbohydrate intake for their activity level. Female athletes also reported a low intake of crucial micronutrients.

Glycogenolysis-Induced Astrocytic Serping1 Expression Regulates Neuroinflammatory Effects on Hippocampal neuron

The bacterial pathogen, lipopolysaccharide (LPS), elicits microglial response and induces cytokine secretion that subsequently activates astrocytes. Recent findings have indicated that LPS-induced activation of postnatal glial cells has led to alterations in synapse formation in hippocampal and cortical neurons, thereby resulting in a prolonged increased risk for seizure or depression. Nevertheless, its mechanisms remain to be fully elucidated. Cellular metabolism has recently gained recognition as a critical regulatory mechanism for the activation of peripheral immune cells, as it supplies the requisite energy and metabolite for their activation. In the present study, we report that LPS did not change the expression of reported astrocyte-derived synaptogenic genes in the postnatal hippocampus; however, it induced upregulation of astrocytic complement component regulator Serping1 within the postnatal hippocampus. As a regulatory mechanism, activation of glycogen degradation (glycogenolysis) governs the expression of a subset of inflammatory-responsive genes including Serping1 through reactive oxygen species (ROS)-NF-κB axis. Our study further demonstrated that glycogenolysis is implicated in neurotoxic phenotypes of astrocytes, such as impaired neuronal synaptogenesis or cellular toxicity. These findings suggested that activation of glycogenolysis in postnatal astrocytes is an essential metabolic pathway for inducing responses in inflammatory astrocytes.

Quantitative Systems Pharmacology-Based Digital Twins Approach Supplements Clinical Trial Data for Enzyme Replacement Therapies in Pompe Disease

Pompe disease is a rare, progressive neuromuscular disease caused by deficient lysosomal glycogen degradation, and includes both late-onset (LOPD) and severe infantile-onset (IOPD) phenotypes. Due to very small patient numbers in IOPD and the high phenotypic heterogeneity observed in this population, a quantitative systems pharmacology (QSP)-based "digital twin" approach was developed to perform an in silico comparison of the efficacy of avalglucosidase alfa vs. the standard of care, in a virtual population of IOPD patients. A QSP model was developed that represents key elements of Pompe disease pathophysiology, including tissue glycogen accumulation and the elevation of the biomarker urine Hex4 in both LOPD and IOPD patients. In this approach, the QSP model was used to generate digital twins of each IOPD patient enrolled in the avalglucosidase alfa clinical program, considering their respective disease burden, demographics, and treatment history. This virtual cohort supplemented clinical observations by simulating and comparing tissue glycogen and urine Hex4 following avalglucosidase alfa treatment vs. the standard of care. The digital twin analysis supports the interpretation that the enhanced reduction in urine Hex4 observed following avalglucosidase alfa treatment is attributable to greater tissue glycogen clearance. Overall, this study provides mechanism-based insight into avalglucosidase alfa efficacy across the phenotypic spectrum of Pompe disease and demonstrates the value of applying a QSP-based digital twin analysis to support rare disease drug development.

Saturated fat in an evolutionary context

Evolutionary perspectives have yielded profound insights in health and medical sciences. A fundamental recognition is that modern diet and lifestyle practices are mismatched with the human physiological constitution, shaped over eons in response to environmental selective pressures. This Darwinian angle can help illuminate and resolve issues in nutrition, including the contentious issue of fat consumption. In the present paper, the intake of saturated fat in ancestral and contemporary dietary settings is discussed. It is shown that while saturated fatty acids have been consumed by human ancestors across time and space, they do not feature dominantly in the diets of hunter-gatherers or projected nutritional inputs of genetic accommodation. A higher intake of high-fat dairy and meat products produces a divergent fatty acid profile that can increase the risk of cardiovascular and inflammatory disease and decrease the overall satiating-, antioxidant-, and nutrient capacity of the diet. By prioritizing fiber-rich and micronutrient-dense foods, as well as items with a higher proportion of unsaturated fatty acids, and in particular the long-chain polyunsaturated omega-3 fatty acids, a nutritional profile that is better aligned with that of wild and natural diets is achieved. This would help prevent the burdening diseases of civilization, including heart disease, cancer, and neurodegenerative conditions. Saturated fat is a natural part of a balanced diet; however, caution is warranted in a food environment that differs markedly from the one to which we are adapted.

Previous short-term disuse dictates muscle gene expression and physiological adaptations to subsequent resistance exercise

Short-term unloading experienced following injury or hospitalisation induces muscle atrophy and weakness. The effects of exercise following unloading have been scarcely investigated. We investigated the functional and molecular adaptations to a resistance training (RT) programme following short-term unloading. Eleven males (22.09 ± 2.91 years) underwent 10 days of unilateral lower limb suspension (ULLS) followed by 21 days of knee extensor RT (three times/week). Data collection occurred at Baseline (LS0), after ULLS (LS10) and at active recovery (AR21). Knee extensor maximum voluntary contraction (MVC) was evaluated. Quadriceps volume was estimated by ultrasonography. Muscle fibre cross-sectional area, fibre type distribution, glycogen content and succinate dehydrogenase (SDH) activity were measured from vastus lateralis biopsies. Mitochondrial-related proteins were quantified by western blot and transcriptional responses were assessed by RNA sequencing. Following ULLS, quadriceps volume and MVC decreased significantly (3.7%, P < 0.05; 29.3%, P < 0.001). At AR21 (vs. LS10), MVC was fully restored (42%) and quadriceps volume increased markedly (18.6%, P < 0.001). Glycogen content and whole-body water increased at AR21 (14%, P < 0.001; 3.1%, P < 0.05). We observed a marked increase in fibre type I at AR21 (38%, P < 0.05). SDH immunoreactivity increased significantly after exercise (20%, P < 0.001). Mitochondrial fusion (MFN1, MFN2 and OPA1) and fission (DRP1) proteins were markedly increased by RT, and the most differentially expressed genes belonged to oxidative phosphorylation pathways. In contrast with what is usually observed after RT, oxidative metabolism, slow fibre type and mitochondrial dynamics were enhanced beyond expected. We propose that prior exposure to short-term muscle unloading may drive the nature of molecular adaptations to subsequent RT. KEY POINTS: Short-term unloading is often experienced during recovery from injuries and hospitalisation, leading to loss of muscle mass and strength. Although exercise can be beneficial in mitigating/reversing such alterations during disuse, only a few studies have focused on the effects of exercise following muscle unloading. With an integrative physiological approach, we aimed to elucidate the basic mechanisms of muscle function recovery in response to 21 days of resistance exercise that followed 10 days of unilateral lower limb suspension (ULLS), assessing whether the mechanisms underlying recovery are defined by a specific reversal of those that occurred during disuse. Resistance training was successful in recovering functional and structural muscle properties after 10 days of ULLS, but in contrast with what is usually observed in response to this training modality, oxidative metabolism and slow fibre type were mostly enhanced. We propose that prior exposure to short-term muscle unloading may drive the adaptations to subsequent exercise.

Low carbohydrate availability promotes a distinct circulating microRNA profile 24 h following aerobic exercise

Low carbohydrate availability during recovery from aerobic exercise alters skeletal muscle microRNA (miRNA) profiles, which may mechanistically regulate exercise recovery. However, its impact on circulating miRNA (c-miRNA) profiles remains unclear. This study aimed to determine the effects of low versus adequate carbohydrate availability on c-miRNA profiles during recovery from aerobic exercise. Nine males (22 ± 4 yr, 1.81 ± 0.09 m, 83.9 ± 11.9 kg, 25.7 ± 2.3 kg/m2, means ± SD) completed this randomized, crossover study comprising two glycogen depletion trials, followed by 24 h of isocaloric refeeding to induce low (LOW; 1.5 g/kg carbohydrate, 3.0 g/kg fat) or adequate (AD; 6.0 g/kg carbohydrate, 1.0 g/kg fat) carbohydrate availability. Total c-miRNA was extracted from serum 24 h following glycogen depletion exercise. Data were log-transformed and analyzed as fold change relative to AD. Bioinformatics was conducted on significant c-miRNA and associated pathways (miRTarBase/KEGG). Follow-up transfection of miR-375-3p mimic or inhibitor into C2C12 cells assessed metabolic, inflammatory, and catabolic pathways at the gene and protein levels. Of the 84 miRNAs assessed, miR-335-5p (-0.49 ± 0.60; P = 0.04) and miR-375-3p (-1.57 ± 1.25; P = 0.01) were significantly lower, and miR-214-3p (1.76 ± 1.85; P = 0.02) was significantly higher in AD versus LOW. In vitro experiments indicated that miR-375-3p regulates catabolic pathways at the gene and protein level. Low carbohydrate availability alters c-miRNA profiles, particularly miR-375-3p, which targets proteostasis and metabolism 24 h into recovery from aerobic exercise. These findings identify unique c-miRNA targets as potential biomarkers for the mechanistic effects of low carbohydrate availability on exercise recovery.NEW & NOTEWORTHY Low carbohydrate consumption (LOW) 24 h in recovery from aerobic exercise elicits a distinct circulating miRNA profile compared with adequate carbohydrate consumption (AD). MicroRNA 375-3p was the most significantly different between the LOW and AD treatments. Follow-up in vitro experiments suggest that AD carbohydrate availability blunts catabolic signaling during postexercise recovery.

Aerobic Exercise and Metformin: A Dual Approach to Enhancing Glycemic Maintenance in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a widespread metabolic condition characterized by elevated glucose levels followed by deficiency in insulin secretion. Metformin notably decreased the incidence of T2DM by 31% and it exerts its effects through various signaling pathways. Databases searched included PubMed, Google Scholar, and Scopus from 2000 to 2024. One of the primary mechanisms involves AMPK activation which causes reduced lipogenesis and improved fatty acid oxidation in the liver and muscles. Key molecules affected by metformin include acetyl-CoA carboxylase (ACC) and sterol regulatory element-binding protein 1c (SREBP-1c), both involved in lipid synthesis regulation. Aerobic exercise has also emerged as a crucial component in managing T2DM due to its improved effects on hyperglycemia and insulin sensitivity. Key signaling pathways affected in T2DM include the PI3K/Akt, AMP-activated protein kinase (AMPK), and MAPK/ERK pathways which play essential roles in regulating glucose homeostasis, glycogenesis, and insulin secretion. When comparing the mechanisms and efficacy of aerobic exercise and metformin, it becomes evident that aerobic exercise primarily enhances physical fitness and metabolic function, while metformin exerts its effects through biochemical pathways involving AMPK activation. Aerobic exercise and metformin are effective for managing T2DM, though they operate through different mechanisms. Regular aerobic exercise improves insulin sensitivity, enhances cardiovascular health, and promotes weight loss, while metformin primarily decreases hepatic gluconeogenesis and enhances insulin secretion. Understanding the intricate signaling pathways affected by metformin and aerobic exercise provides valuable insights into its mechanisms of action and clinical implications for treating diabetic patients effectively.

International society of sports nutrition position stand: ketogenic diets

POSITION STATEMENT

The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the use of a ketogenic diet in healthy exercising adults, with a focus on exercise performance and body composition. However, this review does not address the use of exogenous ketone supplements. The following points summarize the position of the ISSN.

1. A ketogenic diet induces a state of nutritional ketosis, which is generally defined as serum ketone levels above 0.5 mM. While many factors can impact what amount of daily carbohydrate intake will result in these levels, a broad guideline is a daily dietary carbohydrate intake of less than 50 grams per day.

2. Nutritional ketosis achieved through carbohydrate restriction and a high dietary fat intake is not intrinsically harmful and should not be confused with ketoacidosis, a life-threatening condition most commonly seen in clinical populations and metabolic dysregulation.

3. A ketogenic diet has largely neutral or detrimental effects on athletic performance compared to a diet higher in carbohydrates and lower in fat, despite achieving significantly elevated levels of fat oxidation during exercise (~1.5 g/min).

4. The endurance effects of a ketogenic diet may be influenced by both training status and duration of the dietary intervention, but further research is necessary to elucidate these possibilities. All studies involving elite athletes showed a performance decrement from a ketogenic diet, all lasting six weeks or less. Of the two studies lasting more than six weeks, only one reported a statistically significant benefit of a ketogenic diet.

5. A ketogenic diet tends to have similar effects on maximal strength or strength gains from a resistance training program compared to a diet higher in carbohydrates. However, a minority of studies show superior effects of non-ketogenic comparators.

6. When compared to a diet higher in carbohydrates and lower in fat, a ketogenic diet may cause greater losses in body weight, fat mass, and fat-free mass, but may also heighten losses of lean tissue. However, this is likely due to differences in calorie and protein intake, as well as shifts in fluid balance.

7. There is insufficient evidence to determine if a ketogenic diet affects males and females differently. However, there is a strong mechanistic basis for sex differences to exist in response to a ketogenic diet.

Inflammation and Physical Performance in Overweight and Obese Schoolchildren

Obesity represents a critical public health concern, often linked to low-grade chronic inflammation starting in childhood. This study aimed to evaluate the impact of a 12-week kinesiotherapy program on physical performance and levels of leptin and C-reactive protein (CRP) in overweight and obese children.

METHODS

Conducted at the Filantropia Municipal Clinical Hospital, 160 children aged 6 to 15 were randomly assigned to a study group (SG, n = 80) and a control group (CG, n = 80). The SG engaged in a tailored kinesiotherapy program, while the CG maintained their usual activities. All children and their families learned five key principles for preventing and managing obesity.

RESULTS

Results indicated significant improvements in the SG, with enhancements in the 6 min walking distance, Timed Up and Go test, and walking cadence (all p-values < 0.001). Notably, leptin and CRP levels (23.02 ± 7.17 to 16.62 ± 7.83, 4.13 ± 1.00 to 3.90 ± 0.95 mg/l, respectively) decreased significantly in the SG, contrasting with no significant changes in the CG. Regression analysis revealed a positive correlation between leptin levels and physical activity in the SG (coefficient: 0.5642, R-squared: 0.266).

CONCLUSIONS

These findings suggest that targeted exercise programs can effectively enhance physical performance and reduce inflammation markers in overweight children, highlighting the importance of tailored interventions in managing obesity.

Junior athletes' nutritional demands: a narrative review of consumption and prevalence of eating disorders

Information regarding the dietary requirements and consumption of young athletes is limited. Hence, the aim of this narrative review is to provide a comprehensive combination of research and review papers on the nutritional status of young athletes aged 5-18 years old, as well as quantitative, qualitative, wholesome foods, food choices, and eating disordered data concerning the dietary requirements for growing young athletes. This study involved systematic searches of electronic databases, including Google Scholar, PubMed, Science Direct, Scopus, and Web of Science. The specific criteria for identifying research papers published in English from July 1980 until May 2024 were included. Only 48 studies out of 1,262 were included in this narrative review. The findings of this study suggest that, compared with adults, junior athletes need a unique approach to meet their dietary needs. Growth, development, and general athletic performance depend on macronutrients, as they are vital nutrients for young active athletes. However, research on enhancing junior athletes' performance is still in progress, and studies on hydration status, and eating disorders are limited.

How Can Promoting Skeletal Muscle Health and Exercise in Children and Adolescents Prevent Insulin Resistance and Type 2 Diabetes?

Skeletal muscle secretome, through its paracrine and endocrine functions, contributes to the maintenance and regulation of overall physiological health. We conducted a narrative review on the role of skeletal muscle and exercise in maintaining glucose homeostasis, driving insulin resistance (IR), and preventing type 2 diabetes in pediatric populations, especially in the context of overweight and obesity. Myokines such as interleukin (IL)-6, IL-8, and IL-15, as well as irisin, myonectin, and myostatin, appear to play a crucial role in IR. Skeletal muscle can also become a target of obesity-induced and IR-induced inflammation. In the correlation between muscle, IR, and inflammation, the role of infiltration of the immune cells and the microvasculature may also be considered. It remains unclear which exercise approach is the best; however, combining aerobic exercise with resistance training seems to be the most effective strategy for managing IR, with high-intensity activities offering superior metabolic benefits and long-term adherence. Encouraging daily participation in enjoyable and engaging exercise is key for long-term commitment and effective glucose metabolism management. Promoting physical activity in children and adolescents must be a top priority for public health, not only in terms of individual quality of life and well-being but also for community health.

Dietary and Lifestyle Management of Functional Hypothalamic Amenorrhea: A Comprehensive Review

Functional Hypothalamic Amenorrhea (FHA) is a condition characterized by the absence of menstruation, which is increasingly affecting young women. However, specific recommendations for treating and preventing this condition are lacking. Based on a review of the available literature, this article provides practical and feasible dietary management recommendations for healthcare professionals and researchers in women's health and nutrition. It answers the question of what interventions and nutritional recommendations are necessary to restore menstrual function in women struggling with FHA. Physicians recommend an energy availability threshold of 30 kcal/kg FFM/day to prevent FHA. Also, energy availability below and above this threshold can inhibit LH pulsation and cause menstrual disorders. In addition, the risk of menstrual disorders increases with a decrease in the caloric content of the diet and the duration of the energy deficit, and women with FHA have significantly lower energy availability than healthy women. It is essential to ensure that adequate kilocalories are provided throughout the day (regular meals that are a source of proper glucose) to avoid a negative energy balance, as glucose has been proven to affect LH pulses and T3 and cortisol concentrations in the body. Dietary intervention should focus on increasing the caloric content of the diet, thus increasing energy availability and restoring energy balance in the body. Treatment and diagnosis should also focus on body composition, not just body weight. An increase in body fat percentage above 22% may be required to restore menstrual function. In women with FHA, even an increase in body fat mass of one kilogram (kg) increases the likelihood of menstruation by 8%. It is advisable to reduce the intensity of physical activity or training volume, while it is not advisable to give up physical activity altogether. It is also important to ensure adequate intake of micronutrients, reduce stress, and incorporate cognitive-behavioral therapy.

The interplay between gut microbiome and physical exercise in athletes

PURPOSE OF REVIEW

The gut microbiome regulates several health and disease-related processes. However, the potential bidirectional relationship between the gut microbiome and physical exercise remains uncertain. Here, we review the evidence related to the gut microbiome in athletes.

RECENT FINDINGS

The effect of physical exercise on the intestinal microbiome and intestinal epithelial cells depends on the type, volume, and intensity of the activity. Strenuous exercise negatively impacts the intestinal microbiome, but adequate training and dietary planning could mitigate these effects. An increase in short-chain fatty acids (SCFAs) concentrations can modulate signaling pathways in skeletal muscle, contributing to greater metabolic efficiency, preserving muscle glycogen, and consequently optimizing physical performance and recovery. Furthermore, higher SCFAs concentrations appear to lower inflammatory response, consequently preventing an exacerbated immune response and reducing the risk of infections among athletes. Regarding dietary interventions, the optimal diet composition for targeting the athlete's microbiome is not yet known. Likewise, the benefits or harms of using probiotics, synbiotics, and postbiotics are not well established, whereas prebiotics appear to optimize SCFAs production.

SUMMARY

The intestinal microbiome plays an important role in modulating health, performance, and recovery in athletes. SCFAs appear to be the main intestinal metabolite related to these effects. Nutritional strategies focusing on the intestinal microbiome need to be developed and tested in well controlled clinical trials.

Aerobic mechanochemical reversible-deactivation radical polymerization

Polymer materials suffer mechano-oxidative deterioration or degradation in the presence of molecular oxygen and mechanical forces. In contrast, aerobic biological activities combined with mechanical stimulus promote tissue regeneration and repair in various organs. A synthetic approach in which molecular oxygen and mechanical energy synergistically initiate polymerization will afford similar robustness in polymeric materials. Herein, aerobic mechanochemical reversible-deactivation radical polymerization was developed by the design of an organic mechano-labile initiator which converts oxygen into activators in response to ball milling, enabling the reaction to proceed in the air with low-energy input, operative simplicity, and the avoidance of potentially harmful organic solvents. In addition, this approach not only complements the existing methods to access well-defined polymers but also has been successfully employed for the controlled polymerization of (meth)acrylates, styrenic monomers and solid acrylamides as well as the synthesis of polymer/perovskite hybrids without solvent at room temperature which are inaccessible by other means.

Nootropic supplements for esports

Background: esports, or organized video game competitions, have been expanding quickly. The use of dietary supplements by esports players appears vulgarized but lacks supporting evidence. Objectives: To outline studies that tested the effects of dietary supplements on video gaming, summarize their findings, highlight knowledge gaps, and recommend future research. Eligibility criteria: Clinical trials published in English between 1990 and 2023 that assessed the effects of dietary supplements on the cognitive performance of video gamers. Sources of evidence: The Web of Science, PubMed, Scopus, and Google Scholar databases. Charting methods: PRISMA's (2020) flow diagram was used to create the data chart. Results: Sixteen studies were outlined. Thirteen were randomized, thirteen applied acute interventions, ten applied a crossover design and only three weren't placebo-controlled. Of the 10 studies that included caffeine (40-200 mg), four reported significant positive effects on cognition (attention, processing speed, working memory), two on first-person shooter video gaming performance (reaction time, hit accuracy, time to hit 60 targets), and one on Tetris game score. All 3 studies that included arginine silicate (1500 mg) reported significant improvements in one or more aspects of cognition (reaction time, attention, visual representation, and spatial planning). Two studies that tested sucrose (21 and 26.8 g) didn't report significant improvements, while one study that tested 26.1 g of glucose registered significant positive effects on processing speed and sustained attention. Conclusions: The published literature has focused on the effects of caffeine, which may exert both positive and negative effects on esports players. Additional, high-quality research is needed.

Tanycytes release glucose using the glucose-6-phosphatase system during hypoglycemia to control hypothalamic energy balance

OBJECTIVE

The liver releases glucose into the blood using the glucose-6-phosphatase (G6Pase) system, a multiprotein complex located in the endoplasmic reticulum (ER). Here, we show for the first time that the G6Pase system is also expressed in hypothalamic tanycytes, and it is required to regulate energy balance.

METHODS

Using automatized qRT-PCR and immunohistochemical analyses, we evaluated the expression of the G6Pase system. Fluorescent glucose analogue (2-NBDG) uptake was evaluated by 4D live-cell microscopy. Glucose release was tested using a glucose detection kit and high-content live-cell analysis instrument, Incucyte s3. In vivo G6pt knockdown in tanycytes was performed by AAV1-shG6PT-mCherry intracerebroventricular injection. Body weight gain, adipose tissue weight, food intake, glucose metabolism, c-Fos, and neuropeptide expression were evaluated at 4 weeks post-transduction.

RESULTS

Tanycytes sequester glucose-6-phosphate (G6P) into the ER through the G6Pase system and release glucose in hypoglycaemia via facilitative glucose transporters (GLUTs). Strikingly, in vivo tanycytic G6pt knockdown has a powerful peripheral anabolic effect observed through decreased body weight, white adipose tissue (WAT) tissue mass, and strong downregulation of lipogenesis genes. Selective deletion of G6pt in tanycytes also decreases food intake, c-Fos expression in the arcuate nucleus (ARC), and Npy mRNA expression in fasted mice.

CONCLUSIONS

The tanycyte-associated G6Pase system is a central mechanism involved in controlling metabolism and energy balance.

Timing Matters: Time of Day Impacts the Ergogenic Effects of Caffeine-A Narrative Review

Caffeine has attracted significant attention from researchers in the sports field due to its well-documented ergogenic effects across various athletic disciplines. As research on caffeine continues to progress, there has been a growing emphasis on evaluating caffeine dosage and administration methods. However, investigations into the optimal timing of caffeine intake remain limited. Therefore, this narrative review aimed to assess the ergogenic effects of caffeine administration at different times during the morning (06:00 to 10:00) and evening (16:00 to 21:00). The review findings suggest that circadian rhythms play a substantial role in influencing sports performance, potentially contributing to a decline in morning performance. Caffeine administration has demonstrated effectiveness in mitigating this phenomenon, resulting in ergogenic effects and performance enhancement, even comparable to nighttime levels. While the specific mechanisms by which caffeine regulates circadian rhythms and influences sports performance remain unclear, this review also explores the mechanisms underlying caffeine's ergogenic effects, including the adenosine receptor blockade, increased muscle calcium release, and modulation of catecholamines. Additionally, the narrative review underscores caffeine's indirect impact on circadian rhythms by enhancing responsiveness to light-induced phase shifts. Although the precise mechanisms through which caffeine improves morning performance declines via circadian rhythm regulation necessitate further investigations, it is noteworthy that the timing of caffeine administration significantly affects its ergogenic effects during exercise. This emphasizes the importance of considering caffeine intake timing in future research endeavors to optimize its ergogenic potential and elucidate its mechanisms.

Nutrition for European Elite Fencers: A Practical Tool for Coaches and Athletes

The aim of this narrative review is to create a comprehensive, innovative, and pragmatic resource to guide elite fencers and coaches in making strategic nutritional choices to enhance performance and facilitate recovery. The literature review identified only 12 articles specifically addressing the topic of nutrition for fencers. Thus, the recommendations provided in this review derive also from articles dealing with similar sports, such as martial arts, and from investigations with European elite fencers and their coaches. For elite fencers, it is suggested to consume daily 7-11 g/kg of body weight (BW) of carbohydrates and 1.5-2 g/kg of BW of proteins and allocate 25% to 30% of the total energy intake to essential fats, with a specific focus on omega-3 fatty acids. The timing of meals, ideally within one hour after exertion, plays a pivotal role in restoring glycogen reserves and preventing injuries. The intake of leucine, creatine, omega-3, collagen, and vitamins C and D is proposed as a strategy for injury recovery. It is worth acknowledging that even when personalized plans are provided, implementation can be challenging, especially during competitions and training camps.

Effects of 24-week Polarized Training vs. Threshold Training in Obese Male Adults

The combination of high volume of moderate-intensity continuous training with a low volume of high-intensity interval training improved body composition and physical capacities in individuals with obesity. However, polarized training (POL) has never been used in adult men with obesity. Thus, the purpose of this study was to investigate changes in body composition and physical capacities induced by a 24-week POL or threshold (THR) program in obese male adults. Twenty male patients (mean age 39.8±6.3 yrs; mean body mass index [BMI] 31.6±2.7 kg∙m-2) participated in this study (n: 10 POL, n: 10 THR). After 24-week, body mass (BM) and fat mass (FM) decreased by -3.20±3.10 kg (P<0.05) and -3.80±2.80 kg (P<0.05), respectively, similarly in both groups. Maximal oxygen uptake (  ̇VO2max) and   ̇VO2 at respiratory compensation point (RCP) increased in the POL group (+8.5±12.2 and+9.0±17.0%, P<0.05) and in the THR group (+4.24±8.64 and+4.0±6.70%, P<0.05), as well   ̇VO2 at gas exchange threshold (GET) increased similarly in both groups (+12.8±12.0%, P<0.05). POL and THR were equally effective in improving body composition and physical capacities in obese subjects. Future studies are needed to determine whether adherence to the training program can be improved by adding a running competition compared with a group without competition at the end of the training program.

Comparison of 10 × 1-minute high-intensity interval training (HIIT) versus 4 × 4-minute HIIT on glucose control and variability in females with type 2 diabetes

Two high-intensity interval training (HIIT) regimens are often used in research and clinical settings. Yet, there has been no direct comparison to determine if one can improve glucose control and variability to a greater extent in individuals living with type 2 diabetes (T2D). Fourteen older females with T2D participated in a semi-randomized control trial where HIIT10 (10 × 1-min intervals at 90% heart rate max; HRmax) and HIIT4 (4 × 4-min intervals at 90% of HRmax) were compared to a control condition (CON; no exercise). Continuous glucose monitoring was used to assess glucose control and variability over 24 h after each condition. Both HIIT10 (-2.1 ± 1.1 mmol/L) and HIIT4 (-2.1 ± 1.3 mmol/L) acutely lowered glucose compared to CON (-0.7 ± 0.8 mmol/L; p = 0.001), with no difference between exercise conditions. This glucose-lowering effect did not persist over the 24-h post-exercise period, as both mean glucose (p = 0.751) and glucose variability (p = 0.168) were not significantly different among conditions. However, exploratory analyses focusing on individuals with less optimal glucose control (above median 24-h mean glucose in the CON condition; n = 7) revealed that 24-h mean glucose (7.4 [7.14-8.92] vs. 8.4 [7.5-9.9] mmol/L; p = 0.048), glucose variability (p = 0.010), and peak glucose (p = 0.048) were lower following HIIT10 compared to CON, while HIIT4 reduced time spent in moderate hyperglycemia compared to CON (p = 0.023). Both HIIT10 and HIIT4 acutely lower glycemia, but the effect does not persist over 24 h. However, in individuals with worse glucose control, HIIT10 may improve mean 24-h glucose and glycemic variability, while HIIT4 may reduce time spent in moderate hyperglycemia.

Supplementation with Lactiplantibacillus brevis GKEX Combined with Resistance Exercise Training Improves Muscle Mass, Strength Performance, and Body Fat Condition in Healthy Humans

In addition to maintaining good exercise and dietary habits, recent studies have shown that probiotics may have potential benefits for muscle mass and strength. It is worth noting that the effects may vary depending on the specific strains used. To date, no studies have analyzed the effects of Lactiplantibacillus brevis in this context. Here, we combine the L. brevis strain GKEX with resistance training to further understand its effects on muscle mass, thickness, performance, and fat loss. In a six-week intervention for a double-blind randomized trial, 52 healthy subjects were divided into two groups (10 male and 16 female participants in each group): a placebo group (two capsules/day, containing 0 CFU of GKEX per capsule) and a GKEX group (two capsules/day, containing 1 × 1010 CFU of GKEX per capsule). Before the intervention, no differences were observed between the two groups in any of the tests (body composition, muscle thickness, exercise performance, and blood parameters). However, supplementation with GKEX significantly improved muscle mass and thickness, as well as grip strength, muscle strength, and explosive performance, when compared to the associated parameters before the intervention. Additionally, GKEX supplementation promoted a reduction in the body fat percentage (p < 0.05). Through analysis of the change amount, we observed that GKEX supplementation yielded significantly improved benefits when compared to the placebo group (p < 0.05). In summary, our findings support the notion that a six-week resistance exercise training program combined with L. brevis GKEX supplementation has superior additive effects that enhance muscle mass and strength performance, while also reducing body fat percentage. This intervention can promote muscle gain and fat loss.

Tea seed saponin‑reduced extract ameliorates palmitic acid‑induced insulin resistance in HepG2 cells

Tea (Camellia sinensis) seed cake is a potential resource that contains a wealth of bioactive compounds. However, the high toxicity of tea saponins in tea seed cake restricts its applications. The present study aimed to i) develop a method of extracting bioactive compounds and reducing tea saponins during the process of tea seed cake extraction and ii) investigate the anti‑insulin resistance effect of tea seed saponin‑reduced extract (TSSRE) in a palmitic acid (PA)‑induced insulin resistance HepG2‑cell model. The concentration of tea saponins in TSSRE was ~10‑fold lower than that in tea seed crude extract (TSCE) after the saponin‑reduction process. In addition, TSSRE cytotoxicity was significantly lower than that of TSCE in HepG2 cells. TSSRE treatment improved glucose consumption as well as glucose transporter (GLUT) 2 and GLUT4 expression levels in PA‑stimulated HepG2 cells. Moreover, TSSRE enhanced the phosphorylation of the insulin receptor substrate 1/protein kinase B/forkhead box protein O1/glycogen synthase kinase 3β and inhibited the elevated expression of phosphoenolpyruvate carboxykinase in PA‑exposed HepG2 cells. The effect of TSSRE on the mediation of the insulin signaling pathway was attributed to the inhibition of PA‑induced mitogen‑activated protein kinase activation. The findings of the present study indicated that TSSRE ameliorates hepatic insulin resistance by ameliorating insulin signaling and inhibiting inflammation-related pathways.

Influence of modified starches on mental performance and physical activity following an exhaustive bout of exercise

Slow-releasing carbohydrates may delay the effects of fatigue after exhaustive exercise. The purpose of this study was to observe the influence that hydrothermally modified starches (HMS) and traditional maltodextrin (MAL) supplements had on physical endurance and mental performance following exhaustive exercise. Male participants completed a VO2 max and 2 days of cycling sessions using a Velotron ergometer. Cycling sessions were performed at 70% of the VO2 max workload for 150 min. Supplements were consumed 30 min before cycling and during exercise at the 120-min mark (1 g CHO/kg body weight). Brain activity was measured using a Neuroscan 64-channel electroencephalogram cap. Go-no-go and N-back tasks were performed before and after cycling bouts. Blood glucose, lactate, ketones, and urine-specific gravity were measured before, during, and after cycling. VO2 and rate of perceived exertion were recorded in 15-min intervals. Ketones increased significantly more for HMS than MAL from pre- to postcycling measurements (p < 0.05). Reaction times for go-no-go and N-back were faster for HMS postexercise. Event-related potential differences were present in both mental tasks following exhaustive exercise. HMS supplementation decreased the impact of cognitive and physical fatigue postexercise.

Nutrition knowledge, weight loss practices, and supplement use in senior competition climbers

Introduction

Sport climbing has gained increased scientific attention, including studies investigating the dietary habits and nutritional requirements of climbers; however, significant gaps in the literature remain. An assessment of nutritional knowledge, weight loss for competition, and supplement use has not been previously reported in senior competition climbing athletes.

Methods

Fifty climbers (26 male, 24 female; BMI 21.6 ± 1.9; 23.7 ± 5.2 years) participated in the study. Participants answered a 72-item questionnaire, comprised of demographic data and three main sections to assess general and sports nutrition knowledge, weight loss strategies, and supplement use.

Results

The mean nutrition knowledge score was 'average', with considerable individual variation (53.5 ± 11.1 %). There were no significant sex differences in the general (GNK) or sport (SNK) nutrition knowledge scores, or effect of age. Significantly higher knowledge was demonstrated by national vs. international athletes for the GNK scores (11.09 ± 1.58 vs. 9.58 ± 1.75; p = 0.028). Participants scored well in questions concerning protein, carbohydrates, alcohol, and supplements, and conversely, performed poorly in hydration and micronutrient related questions. Less than one-fifth of respondents had access to a dietitian. Forty-six percent of males and 38% of female climbers reported intentional weight loss for competition on at least one occasion. Of those, ~76% reported utilizing concerning practices, including methods that conform with disordered eating and/or eating disorders, dehydration, vomiting, and misuse of laxatives. Approximately 65% of athletes reported using at least one nutritional supplement in the previous 6 months, with 44% reporting multiple supplement use. There was no significant difference in supplement use between sexes or competition level.

Discussion

Due to the established importance of nutritional intake on athlete health and performance, educational support should be employed to improve knowledge in climbers and address shortcomings. Moreover, intentional weight loss for climbing competition is common, with most athletes achieving ~3-8% body weight loss over ≥2 weeks. It is crucial that professionals working with competitive climbers are vigilant in identifying athletes at risk of concerning weight management and establish referral pathways to the appropriate specialist services. High quality intervention trials to assess the efficacy of ergogenic aids in climbing remains inadequate.

Assessing exogenous carbohydrate intake needed to optimize human endurance performance across sex: insights from modeling runners pursuing a sub-2-h marathon

Carbohydrate (CHO) availability sustains high metabolic demands during prolonged exercise. The adequacy of current CHO intake recommendations, 30-90 g·h-1 dependent on CHO mixture and tolerability, to support elite marathon performance is unclear. We sought to scrutinize the current upper limit recommendation for exogenous CHO intake to support modeled sub-2-h marathon (S2M) attempts across elite male and female runners. Male and female runners (n = 120 each) were modeled from published literature with reference characteristics necessary to complete a S2M (e.g., body mass and running economy). Completion of a S2M was considered across a range of respiratory exchange rates, with maximal starting skeletal muscle and liver glycogen content predicted for elite male and female runners. Modeled exogenous CHO bioavailability needed for male and female runners were 93 ± 26 and 108 ± 22 g·h-1, respectively (P < 0.0001, d = 0.61). Without exogenous CHO, males were modeled to deplete glycogen in 84 ± 7 min, females in 71 ± 5 min (P < 0.0001, d = 2.21) despite higher estimated CHO oxidation rates in males (5.1 ± 0.5 g·h-1) than females (4.4 ± 0.5 g·h-1; P < 0.0001, d = 1.47). Exogenous CHO intakes ≤ 90 g·h-1 are insufficient for 65% of modeled runners attempting a S2M. Current recommendations to support marathon performance appear inadequate for elite marathon runners but may be more suitable for male runners in pursuit of a S2M (56 of 120) than female runners (28 of 120).NEW & NOTEWORTHY This study scrutinizes the upper limit of exogenous carbohydrate (CHO) recommendations for elite male and female marathoners by modeling sex-specific needs across an extreme metabolic challenge lasting ∼2 h, a sub-2-h marathon. Contemporary nutritional guidelines to optimize marathon performance appear inadequate for most elite marathon runners but appear more appropriate for males over their female counterparts. Future research examining possible benefits of exogenous CHO intakes > 90 g·h-1 should prioritize female athlete study inclusion.

Compositional Aspects of Beverages Designed to Promote Hydration Before, During, and After Exercise: Concepts Revisited

Hypohydration can impair aerobic performance and deteriorate cognitive function during exercise. To minimize hypohydration, athletes are recommended to commence exercise at least euhydrated, ingest fluids containing sodium during long-duration and/or high-intensity exercise to prevent body mass loss over 2% and maintain elevated plasma osmolality, and rapidly restore and retain fluid and electrolyte homeostasis before a second exercise session. To achieve these goals, the compositions of the fluids consumed are key; however, it remains unclear what can be considered an optimal formulation for a hydration beverage in different settings. While carbohydrate-electrolyte solutions such as sports drinks have been extensively explored as a source of carbohydrates to meet fuel demands during intense and long-duration exercise, these formulas might not be ideal in situations where fluid and electrolyte balance is impaired, such as practicing exercise in the heat. Alternately, hypotonic compositions consisting of moderate to high levels of electrolytes (i.e., ≥45 mmol/L), mainly sodium, combined with low amounts of carbohydrates (i.e., <6%) might be useful to accelerate intestinal water absorption, maintain plasma volume and osmolality during exercise, and improve fluid retention during recovery. Future studies should compare hypotonic formulas and sports drinks in different exercise settings, evaluating different levels of sodium and/or other electrolytes, blends of carbohydrates, and novel ingredients for addressing hydration and rehydration before, during, and after exercise.

The Potential Role of Nutrition in Overtraining Syndrome: A Narrative Review

Competition between athletes and an increase in sporting knowledge have greatly influenced training methods while increasing the number of them more and more. As a result, the number of athletes who have increased the number and intensity of their workouts while decreasing recovery times is rising. Positive overtraining could be considered a natural and fundamental process when the result is adaptation and improved performance; however, in the absence of adequate recovery, negative overtraining could occur, causing fatigue, maladaptation, and inertia. One of the earliest forms of fatigue is overreaching. It is considered to be an accumulation of training that leads to reduced sports performance, requiring days or weeks to recover. Overreaching, if followed by adequate recovery, can lead to an increase in athletic performance. Nonetheless, if overreaching becomes extreme, combined with additional stressors, it could lead to overtraining syndrome (OTS). OTS, caused by systemic inflammation, leads to central nervous system (CNS) effects, including depressed mood, further inflammation, central fatigue, and ultimately neurohormonal changes. There are therefore not only physiological, biochemical, and immunological but also psychological symptoms or markers that must be considered, independently or together, being intrinsically linked with overtraining, to fully understand OTS. However, to date, there are very few published studies that have analyzed how nutrition in its specific food aspects, if compromised during OTS, can be both etiology and consequence of the syndrome. To date, OTS has not yet been fully studied, and the topic needs further research. The purpose of this narrative review is therefore to study how a correct diet and nutrition can influence OTS in all its aspects, from prevention to treatment.

Products for Sportspeople Containing Constituents Derived from the Common Bean Phaseolus vulgaris L. (Fabaceae)-A Narrative Literature Review

The third-largest land plant family, Fabaceae (Papilionaceae), includes trees, shrubs, and perennial or annual herbaceous plants containing both numerous beneficial constituents (e.g., proteins, carbohydrates, dietary fibre) and antinutrients (e.g., saponins, tannins, phytic acid, gossypol, lectins). The consumption of leguminous plants allows sports people to complete their requirements for nourishment but, on the other hand, it contributes to digestive system ailments. Therefore, the aim of the presented study was to review the experimental articles and patents referring to the application of common (kidney) bean (Phaseolus vulgaris L.)-based nutritional products for athletes. The survey of the literature was carried out according to PRISMA statements by browsing Scopus, PubMed and ISI Web of Science databases, as well as Google Scholar, Google Patents and Espacenet Patent Search engines using factorial combinations of the following keywords: ('common bean' or 'kidney bean' or 'Phaseolus vulgaris') and ('athlete' or 'sport') and ('food' or 'nutrition' or 'diet'). Altogether, 84 patents issued in the years 1995-2023 were noted. The majority of patents were developed by research teams consisting of at least four authors representing scientists affiliated in the United States of America and China. The patents refer to the production of food ingredients, nutritional products, and compositions: (i) for relieving fatigue, enhancing endurance, and increasing muscle mass and strength, (ii) for maintaining physical and mental health, and (iii) for controlling body weight. Moreover, the analysis of 19 original articles indicated the substantial acceptability of meals containing the common bean. To summarize, the performed investigations demonstrate the considerable use of Phaseolus vulgaris in sport nutrition and the growing acceptance of this trend.

Considerations of Low Carbohydrate Availability (LCA) to Relative Energy Deficiency in Sport (RED-S) in Female Endurance Athletes: A Narrative Review

The purpose of this narrative review is to identify health and performance consequences associated with LCA in female endurance athletes. The intake of carbohydrates (CHO) before, during, and after exercise has been demonstrated to support sport performance, especially endurance activities which rely extensively on CHO as a fuel source. However, low energy availability (LEA) and low carbohydrate availability (LCA) are common in female athletes. LEA occurs when energy intake is insufficient compared to exercise energy expenditure, and LEA-related conditions (e.g., Female Athlete Triad (Triad) and Relative Energy Deficiency in Sport (RED-S)) are associated with a myriad of health and performance consequences. The RED-S model highlights 10 health consequences and 10 performance consequences related to LEA. The independent effect of LCA on health and performance has been under-researched, despite current CHO intake being commonly insufficient in athletes. It is proposed that LCA may not only contribute to LEA but also have independent health and performance consequences in athletes. Furthermore, this review highlights current recommendations for CHO intake, as well as recent data on LCA prevalence and menstrual cycle considerations. A literature review was conducted on PubMed, Science Direct, and ResearchGate using relevant search terms (i.e., "low carbohydrate/energy availability", "female distance runners"). Twenty-one articles were identified and twelve met the inclusion criteria. The total number of articles included in this review is 12, with 7 studies illustrating that LCA was associated with direct negative health and/or performance implications for endurance-based athletes. Several studies included assessed male athletes only, and no studies included a female-only study design. Overall, the cumulative data show that female athletes remain underrepresented in sports science research and that current CHO intake recommendations and strategies may fail to consider female-specific adaptations and hormone responses, such as monthly fluctuations in estrogen and progesterone throughout the menstrual cycle. Current CHO guidelines for female athletes and exercising women need to be audited and explored further in the literature to support female athlete health and performance.

Effects of combined training or moderate intensity continuous training during a 3-week multidisciplinary body weight reduction program on cardiorespiratory fitness, body composition, and substrate oxidation rate in adolescents with obesity

This study aimed to investigate the effects of combined training (COMB, a combination of moderate-intensity continuous training-MICT and high-intensity interval training-HIIT) vs. continuous MICT administered during a 3-week in-hospital body weight reduction program (BWRP) on body composition, physical capacities, and substrate oxidation in adolescents with obesity. The 3-week in-hospital BWRP entailed moderate energy restriction, nutritional education, psychological counseling, and two different protocols of physical exercise. Twenty-one male adolescents with obesity (mean age: 16.1 ± 1.5 years; mean body mass index [BMI] 37.8 ± 4.5 kg m-2) participated in this randomized control trial study (n:10 for COMB, n:11 MICT), attending ~ 30 training sessions. The COMB group performed 3 repetitions of 2 min at 95% of peak oxygen uptake (V'O2 peak) (e.g., HIIT ≤ 20%), followed by 30 min at 60% of V'O2 peak (e.g., MICT ≥ 80%). Body composition, V'O2 peak, basal metabolic rate (BMR), energy expenditure, and substrate oxidation rate were measured during the first week (W0) and at the end of three weeks of training (W3). The two training programs were equivalent in caloric expenditure. At W3, body mass (BM) and fat mass (FM) decreased significantly in both groups, although the decrease in BM was significantly greater in the MICT group than in the COMB group (BM: - 5.0 ± 1.2 vs. - 8.4 ± 1.5, P < 0.05; FM: - 4.3 ± 3.0 vs. - 4.2 ± 1.9 kg, P < 0.05). V'O2 peak increased only in the COMB by a mean of 0.28 ± 0.22 L min-1 (P < 0.05). The maximal fat oxidation rate (MFO) increased only in the COMB group by 0.04 ± 0.03 g min-1 (P < 0.05). COMB training represents a viable alternative to MICT for improving anthropometric characteristics, physical capacities, and MFO in adolescents with obesity during a 3-week in-hospital BWRP.

Active recovery vs hot- or cold-water immersion for repeated sprint ability after a strenuous exercise training session in elite skaters

This study compared the acute effects of three recovery methods: active recovery (AR), hot- and cold-water immersion (HWI and CWI, respectively), used between two training sessions in elite athletes. Twelve national-team skaters (7 males, 5 females) completed three trials according to a randomized cross-over study. Fifteen minutes after an exhaustive ice-skating training session, participants underwent 20 min of HWI (41.1 ± 0.5°C), 15 min of CWI (12.1 ± 0.7°C) or 15 min of active recovery (AR). After 1 h 30 min of the first exercise, they performed a repeated-sprint cycling session. Average power output was slightly but significantly higher for AR (767 ± 179 W) and HWI (766 ± 170 W) compared to CWI (738 ± 156 W) (p = 0.026, d = 0.18). No statistical difference was observed between the conditions for both lactatemia and rating of perceived exertion. Furthermore, no significant effect of recovery was observed on the fatigue index calculated from the repeated sprint cycling exercises (p > 0.05). Finally, a positive correlation was found between the average muscle temperature measured during the recoveries and the maximal power output obtained during cycling exercises. In conclusion, the use of CWI in between high-intensity training sessions could slightly impair the performance outcomes compared to AR and HWI. However, studies with larger samples are needed to confirm these results, especially in less trained athletes.

Optimally controlling nutrition and propulsion force in a long distance running race

INTRODUCTION

Runners competing in races are looking to optimize their performance. In this paper, a runner's performance in a race, such as a marathon, is formulated as an optimal control problem where the controls are: the nutrition intake throughout the race and the propulsion force of the runner. As nutrition is an integral part of successfully running long distance races, it needs to be included in models of running strategies.

METHODS

We formulate a system of ordinary differential equations to represent the velocity, fat energy, glycogen energy, and nutrition for a runner competing in a long-distance race. The energy compartments represent the energy sources available in the runner's body. We allocate the energy source from which the runner draws, based on how fast the runner is moving. The food consumed during the race is a source term for the nutrition differential equation. With our model, we are investigating strategies to manage the nutrition and propulsion force in order to minimize the running time in a fixed distance race. This requires the solution of a nontrivial singular control problem.

RESULTS

As the goal of an optimal control model is to determine the optimal strategy, comparing our results against real data presents a challenge; however, in comparing our results to the world record for the marathon, our results differed by 0.4%, 31 seconds. Per each additional gel consumed, the runner is able to run 0.5 to 0.7 kilometers further in the same amount of time, resulting in a 7.75% increase in taking five 100 calorie gels vs no nutrition.

DISCUSSION

Our results confirm the belief that the most effective way to run a race is to run approximately the same pace the entire race without letting one's energies hit zero, by consuming in-race nutrition. While this model does not take all factors into account, we consider it a building block for future models, considering our novel energy representation, and in-race nutrition.

Effects of phenylcapsaicin on aerobic capacity and physiological parameters in active young males: a randomized, triple-blinded, placebo-controlled, crossover trial

Objective: Phenylcapsaicin (PC) is a new capsaicin analog which has exhibited a higher bioavailability. This sudy assessed the effects of a low dose (LD) of 0.625 mg and a high dose (HD) of 2.5 mg of PC on aerobic capacity, substrate oxidation, energy metabolism and exercise physiological variables in young males. Materials and methods: Seventeen active males (age = 24.7 ± 6.0 years) enrolled to this randomized, triple-blinded, placebo-controlled, crossover trial. Participants attended the laboratory on 4 sessions separated by 72-96 h. A submaximal exercise test [to determine maximal fat oxidation (MFO) and the intensity at MFO (FATmax)] followed by a maximal incremental test (to determine VO2_max) were performed in a preliminary session. The subsequent sessions only differed in the supplement ingested [LD, HD or placebo (PLA)] and consisted of a steady-state test (60 min at FATmax) followed by a maximal incremental test. Energy metabolism, substrate oxidation, heart rate, general (gRPE) and quadriceps (RPEquad) rate of perceived exertion, skin temperature and thermal perception were tested. Results: Clavicle thermal perception was lower in HD compared to PLA and LD (p = 0.04) across time. HD reduced maximum heart rate in comparison to PLA and LD (p = 0.03). LD reported higher general RPE (RPEg) values during the steady-state test compared to PLA and HD across time (p = 0.02). HD and LD elicited higher peak of fat oxidation during the steady-state test compared with PLA (p = 0.05). Intra-test analyses revealed significant differences for fat oxidation (FATox) in favor of HD and LD compared to PLA (p = 0.002 and 0.002, respectively), and for carbohydrate oxidation (CHOox) (p = 0.05) and respiratory exchange ratio (RER) (p = 0.03) for PLA. In the incremental test, only general RPE at 60% of the maximal intensity (W) differed favoring HD (p ≤ 0.05). Conclusion: Therefore, PC may contribute to increase aerobic capacity through the improvement of fat oxidation, maximum heart rate and perceptual responses during exercise.

An Intense Bout of Acute Aerobic Exercise, but Not a Carbohydrate Supplement, Improves Cognitive Task Performance in a Sample of Black, Indigenous, and People of Color (BIPOC) Student Athletes

BACKGROUND

There are contradictory findings in the literature on whether an acute bout of aerobic exercise leads to a post-exercise improvement in cognitive function (CF). Moreover, participants used in the published literature are not representative of the racial make-up of sport or tactical populations.

METHODS

A randomized crossover design was incorporated, with participants randomly consuming water or a carbohydrate sports drink within the first 3 min of a graded maximal exercise test (GMET) conducted in a laboratory. Twelve self-identified African American participants, (seven males, five females, age = 21.42 ± 2.38 years, height = 174.94 ± 12.55 cm, mass = 82.45 ± 33.09 kg) completed both testing days. Participants completed the CF tests immediately pre- and post-GMET. CF was assessed with the Stroop color and word task (SCWT) and concentration task grid (CTG). Participants completed the GMET when they reported a score of 20 on the Borg ratings of perceived exertion scale.

RESULTS

Time to complete the SCWT incongruent task (p < 0.001) and CTG performance (p < 0.001) significantly improved post-GMET in both conditions. VO_2max was positively correlated with pre- and post-GMET SCWT performance.

CONCLUSIONS

The findings of our study suggest that an acute bout of maximal exercise significantly improves CF. Additionally, cardiorespiratory fitness is positively associated with CF in our sample of student athletes from a historically Black college and university.

Anti-fatigue properties of the ethanol extract of Moringa oleifera leaves in mice

BACKGROUND

Moringa oleifera (M. oleifera) leaves are rich in nutrients and bioactive ingredients. This study was aimed at evaluating the anti-fatigue effect of the ethanol extract of M. oleifera leaves (MLEE) on mice and its primary mechanism of action using a weight-loaded forced swimming test. In the present study, MLEE was prepared by ultrasound-assisted extraction, and its anti-fatigue effect and antioxidant capacity were evaluated in mice. Mice were administrated MLEE (320 mg kg^-1 body weight) for 15 days.

RESULTS

MLEE supplementation significantly increased levels of glucose and non-esterified fatty acids (NEFA), while decreasing levels of lactate and blood urea nitrogen in serum (P < 0.05); the levels of glycogen in the liver and muscle were also increased, as was the activity of glycogen synthase and the level of NEFA in muscle (P < 0.05). According to a Western blot analysis, MLEE increased the expression of AMPKα1, JNK, AKT and STAT3 in the muscle of mice.

CONCLUSION

Our findings indicate that MLEE has an anti-fatigue effect via the AMPK-linked route, which enables it to control energy metabolism and enhance antioxidant enzyme activity. © 2023 Society of Chemical Industry.

Effects of 12-week combined training versus high intensity interval training on cardiorespiratory fitness, body composition and fat metabolism in obese male adults

Background

/Objectives: A weekly combination of a high volume of moderate-intensity continuous training (MICT) with a low volume of high-intensity interval training (HIIT) provides important improvements in body composition and physical capacities in individuals with obesity. However, previous studies did not determine the weekly proportions of HIIT and MICT a priori. This study aimed to investigate changes in body composition, physical capacities and the fat oxidation rate in obese male adults by comparing a combination of MICT and HIIT, called combined training (COMB), with HIIT for a 12-week period.

Methods

Thirty-four obese male adults (mean age: 39.4 ± 7.0 y; mean body mass index [BMI] 34.0 ± 4.2 kg m-2) participated in this study (n = 18 for COMB, n = 16 HIIT), attending ∼ 36 training sessions. The COMB group performed 3 repetitions of 2 min at 95% of peak oxygen uptake (V'O2 peak) (e.g., HIIT ≤20%), followed by 30 min at 60% of VO2 peak (e.g., MICT ≥80%). The HIIT group performed 5-7 repetitions of 2 min at 95% of VO2 peak. At baseline (PRE) and at the end of the training period (POST), body composition, VO2 peak, and the fat oxidation rate were measured. The two training programs were equivalent in caloric expenditure.

Results

At POST, body mass (BM) and fat mass (FM) decreased by a mean of 3.09 ± 3.21 kg and 3.90 ± 2.40 kg, respectively (P < 0.05), in both groups and V'O2 peak increased in both groups by a mean of 0.47 ± 0.34 L min-1 (P < 0.05). The maximal fat oxidation rate increased similarly in both groups from 0.32 ± 0.05 to 0.36 ± 0.06 g min-1 (P < 0.05).

Conclusion

COMB training represents a viable alternative to HIIT to improve anthropometric characteristics, physical capacities and fat oxidation in obese male adults.

Obesity, diabetes mellitus, and cardiometabolic risk: An Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2023

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) is intended to provide clinicians an overview of type 2 diabetes mellitus (T2DM), an obesity-related cardiometabolic risk factor.

Methods

The scientific support for this CPS is based upon published citations and clinical perspectives of OMA authors.

Results

Topics include T2DM and obesity as cardiometabolic risk factors, definitions of obesity and adiposopathy, and mechanisms for how obesity causes insulin resistance and beta cell dysfunction. Adipose tissue is an active immune and endocrine organ, whose adiposopathic obesity-mediated dysfunction contributes to metabolic abnormalities often encountered in clinical practice, including hyperglycemia (e.g., pre-diabetes mellitus and T2DM). The determination as to whether adiposopathy ultimately leads to clinical metabolic disease depends on crosstalk interactions and biometabolic responses of non-adipose tissue organs such as liver, muscle, pancreas, kidney, and brain.

Conclusions

This review is intended to assist clinicians in the care of patients with the disease of obesity and T2DM. This CPS provides a simplified overview of how obesity may cause insulin resistance, pre-diabetes, and T2DM. It also provides an algorithmic approach towards treatment of a patient with obesity and T2DM, with "treat obesity first" as a priority. Finally, treatment of obesity and T2DM might best focus upon therapies that not only improve the weight of patients, but also improve the health outcomes of patients (e.g., cardiovascular disease and cancer).

Seasonal Oxy-Inflammation and Hydration Status in Non-Elite Freeskiing Racer: A Pilot Study by Non-Invasive Analytic Method

Freeskiing is performed in an extreme environment, with significant physical effort that can induce reactive oxygen species (ROS) generation and dehydration. This study aimed to investigate the evolution of the oxy-inflammation and hydration status during a freeskiing training season with non-invasive methods. Eight trained freeskiers were investigated during a season training: T0 (beginning), T1-T3 (training sessions), and T4 (after the end). Urine and saliva were collected at T0, before (A) and after (B) T1-T3, and at T4. ROS, total antioxidant capacity (TAC), interleukin-6 (IL-6), nitric oxide (NO) derivatives, neopterin, and electrolyte balance changes were investigated. We found significant increases in ROS generation (T1A-B +71%; T2A-B +65%; T3A-B +49%; p < 0.05-0.01) and IL-6 (T2A-B +112%; T3A-B +133%; p < 0.01). We did not observe significant variation of TAC and NOx after training sessions. Furthermore, ROS and IL-6 showed statistically significant differences between T0 and T4 (ROS +48%, IL-6 +86%; p < 0.05). Freeskiing induced an increase in ROS production, which can be contained by antioxidant defense activation, and in IL-6, as a consequence of physical activity and skeletal muscular contraction. We did not find deep changes in electrolytes balance, likely because all freeskiers were well-trained and very experienced.

Effects of Broad-Spectrum Antibiotic Treatment or Germ-Free Status on Endurance Performance and Exercise Adaptations in Mice

PURPOSE

Endurance exercise alters the gut microbiome independently of diet. The extent to which gut microbes are responsible for physiologic adaptations to exercise training is unknown. The purpose of these experiments was to determine the role of gut microbes in performance and muscle adaptation to 6 wk of voluntary wheel running (VWR) in mice.

METHODS

We depleted microbes with broad-spectrum antibiotic (ABX) treatment and used germ-free (GF) mice to determine effects on adaptations to VWR. Male and female C57Bl/6 mice ( n = 56) were assigned to daily VWR or sedentary conditions. After the intervention, treadmill endurance and glucose tolerance were assessed, and gastrocnemius and soleus tissues were harvested and analyzed for citrate synthase (CS) enzyme activity and expression of exercise training-sensitive genes.

RESULTS

ABX treatment and GF status resulted in VWR volumes ~22% and 26% lower than controls, respectively. Analysis of variance revealed that, although VWR increased treadmill endurance, ABX had no effect. GF status significantly reduced treadmill performance in trained GF mice after training. VWR increased gastrocnemius CS enzyme activity in all groups, and ABX and GF status did not reduce the VWR effect. VWR also increased muscle expression of PGC1a, but this was not affected by ABX treatment.

CONCLUSIONS

ABX treatment and GF status reduced VWR behavior but did not affect VWR-induced adaptations in endurance capacity, CS activity, or expression of muscle metabolic genes. However, GF status reduced endurance capacity. These data indicated that reducing microbes in adulthood does not inhibit endurance training adaptations in C57Bl/6 mice, but that GF mice possess a reduced responsiveness to endurance exercise training, perhaps because of a developmental defect associated with lack of microbes from birth.

Sediment pollutant exposures caused hepatotoxicity and disturbed glycogenesis

Liver metabolic syndrome, which involves impaired hepatic glycogen synthesis, is persistently increased by exposure to environmental pollutants. Most studies have investigated the pathogenesis of liver damage caused by single metal species or pure organics. However, under normal circumstances, the pollutants that we are exposed to are usually chemical mixtures that accumulate over time. Sediments are long-term repositories for environmental pollutants due to their environmental cycles, which make them good samples for evaluating the effect of environmental pollutants on the liver via bioaccumulation. This study aimed to clarify the effects of sediment pollutants on liver damage. Our results indicate that industrial wastewater sediment (downstream) is more cytotoxic than sediments from other zones. Downstream sediment extract (DSE) causes hepatotoxicity, stimulates reactive oxygen species (ROS) generation, triggers mitochondrial dysfunction, induces cell apoptosis, and results in the release of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) proteins. Additionally, to elucidate the underlying mechanism by which sediment pollutants disturb hepatic glycogen synthesis, we investigated the effects of different sediment samples from different pollution situations on glycogen synthesis in liver cell lines. It was found that DSE induced multiple severe impairments in liver cells, and disturbed glycogen synthesis more than under other conditions. These impairments include decreased hepatic glycogen synthesis via inhibition and insulin receptor substrate 1 (IRS-1) /AKT /glycogen synthase kinase3β (GSK3β)-mediated glycogen synthase (GYS) inactivation. To our knowledge, this study provides the first detailed evidence of in vitro sediment-accumulated toxicity that interferes with liver glycogen synthesis, leading to hepatic cell damage through apoptosis.

Durability is improved by both low and high intensity endurance training

Introduction: This is one of the first intervention studies to examine how low- (LIT) and high-intensity endurance training (HIT) affect durability, defined as 'time of onset and magnitude of deterioration in physiological-profiling characteristics over time during prolonged exercise'. Methods: Sedentary and recreationally active men (n = 16) and women (n = 19) completed either LIT (average weekly training time 6.8 ± 0.7 h) or HIT (1.6 ± 0.2 h) cycling for 10 weeks. Durability was analyzed before and after the training period from three factors during 3-h cycling at 48% of pretraining maximal oxygen uptake (VO_2max): 1) by the magnitude and 2) onset of drifts (i.e. gradual change in energy expenditure, heart rate, rate of perceived exertion, ventilation, left ventricular ejection time, and stroke volume), 3) by the 'physiological strain', defined to be the absolute responses of heart rate and its variability, lactate, and rate of perceived exertion. Results: When all three factors were averaged the durability was improved similarly (time x group p = 0.42) in both groups (LIT: p = 0.03, g = 0.49; HIT: p = 0.01, g = 0.62). In the LIT group, magnitude of average of drifts and their onset did not reach statistically significance level of p < 0.05 (magnitude: 7.7 ± 6.8% vs. 6.3 ± 6.0%, p = 0.09, g = 0.27; onset: 106 ± 57 min vs. 131 ± 59 min, p = 0.08, g = 0.58), while averaged physiological strain improved (p = 0.01, g = 0.60). In HIT, both magnitude and onset decreased (magnitude: 8.8 ± 7.9% vs. 5.4 ± 6.7%, p = 0.03, g = 0.49; onset: 108 ± 54 min vs. 137 ± 57 min, p = 0.03, g = 0.61), and physiological strain improved (p = 0.005, g = 0.78). VO_2max increased only after HIT (time x group p < 0.001, g = 1.51). Conclusion: Durability improved similarly by both LIT and HIT based on reduced physiological drifts, their postponed onsets, and changes in physiological strain. Despite durability enhanced among untrained people, a 10-week intervention did not alter drifts and their onsets in a large amount, even though it attenuated physiological strain.

Factors associated with high-level endurance performance: An expert consensus derived via the Delphi technique

There is little agreement on the factors influencing endurance performance. Endurance performance often is described by surrogate variables such as maximum oxygen consumption, lactate threshold, and running economy. However, other factors also determine success and progression of high-level endurance athletes. Therefore, the aim was to identify the relevant factors for endurance performance assessed by international experts by adhering to a structured communication method (i.e., Delphi technique). Three anonymous evaluation rounds were conducted initiated by a list of candidate factors (n = 120) serving as baseline input variables. The items that achieved ≥70% of agreement in round 1 were re-evaluated in a second round. Items with a level of agreement of ≥70% in round 2 reached consensus and items with a level of agreement of 40-69% in round 2 were re-rated in a third round followed by a consensus meeting. Round 1 comprised of 27 panellists (n = 24 male) and in round 2 and 3 18 (n = 15 male) of the 27 panellists remained. Thus, the final endurance expert panel comprised of 18 international experts (n = 15 male) with 20 years of experience on average. The consensus report identified the following 26 factors: endurance capacity, running economy, maximal oxygen consumption, recovery speed, carbohydrate metabolism, glycolysis capacity, lactate threshold, fat metabolism, number of erythrocytes, iron deficiency, muscle fibre type, mitochondrial biogenesis, hydrogen ion buffering, testosterone, erythropoietin, cortisol, hydration status, vitamin D deficiency, risk of non-functional overreaching and stress fracture, healing function of skeletal tissue, motivation, stress resistance, confidence, sleep quality, and fatigue. This study provides an expert-derived summary including 26 key factors for endurance performance, the "FENDLE" factors (FENDLE = Factors for ENDurance Level). This consensus report may assist to optimize sophisticated diagnostics, personalized training strategies and technology.