Altered carbohydrate oxidation during exercise in overreached endurance athletes is applicable to training monitoring with continuous glucose monitors.

PURPOSE: The purpose of the study was to investigate whether carbohydrate utilization is altered during exercise in overreached endurance athletes and examine the utility of continuous glucose monitors (CGM) to detect overreaching status. METHODS: Eleven endurance athletes (M:8, F:3) completed a 5-week training block consisting of 1 week of reduced training (PRE), 3 weeks of high-intensity overload training (POST), and 1 week of recovery training (REC). Participants completed a Lamberts and Lambert Submaximal Cycling Test (LSCT) and 5 km time-trial at PRE, POST, and REC time points, 15 min following the ingestion of a 50 g glucose beverage with glucose recorded each minute via CGM. RESULTS: Performance in the 5 km time-trial was reduced at POST (∆-7 ± 10 W, p = 0.04, η p 2 = 0.35) and improved at REC (∆12 ± 9 W from PRE, p = 0.01, η p 2 = 0.66), with reductions in peak lactate (∆-3.0 ± 2.0 mmol/L, p = 0.001, η p 2 = 0.71), peak HR (∆-6 ± 3 bpm, p < 0.001, η p 2 = 0.86), and Hooper-Mackinnon well-being scores (∆10 ± 5 a.u., p < 0.001, η p 2 = 0.79), indicating athletes were functionally overreached. The respiratory exchange ratio was suppressed at POST relative to REC during the 60% (POST: 0.80 ± 0.05, REC: 0.87 ± 0.05, p < 0.001, η p 2 = 0.74), and 80% (POST: 0.93 ± 0.05, REC: 1.00 ± 0.05, p = 0.003, η p 2 = 0.68) of HR-matched submaximal stages of the LSCT. CGM glucose was reduced during HR-matched submaximal exercise in the LSCT at POST (p = 0.047, η p 2 = 0.36), but not the 5 km time-trial (p = 0.07, η p 2 = 0.28) in overreached athletes. CONCLUSION: This preliminary investigation demonstrates a reduction in CGM-derived glucose and carbohydrate oxidation during submaximal exercise in overreached athletes. The use of CGM during submaximal exercise following standardized nutrition could be employed as a monitoring tool to detect overreaching in endurance athletes.

Hair cortisol is a physiological indicator of training stress for female footballers.

PURPOSE: Chronic physical stress in female athletes can reduce mental health and athletic performance. Therefore, a chronic physical stress assessment method is required. METHODS: This study examined whether hair cortisol concentration (HCC) predicted chronic physical stress changes in female university football players. We took measurements in August and December, just before the Japan college national tournament. RESULTS: Self-reported training load was significantly positively correlated with HCC. Self-reported training load had no significant relationship with fatigue as measured by the Profile of Mood States 2nd Edition or with the stressors from the Stressor Scale for College Students. HCC was negatively correlated with reaction time in the spatial Stroop task, although the repeated correlation analysis showed no significant relationship. CONCLUSION: These results suggest that the chronic physical stress experienced by female footballers cannot be predicted by psychological indicators; however, they can be predicted by HCC, which could be used to prevent overtraining in these athletes.

A Narrative Review on Adipose Tissue and Overtraining: Shedding Light on the Interplay among Adipokines, Exercise and Overtraining.

Lifestyle factors, particularly physical inactivity, are closely linked to the onset of numerous metabolic diseases. Adipose tissue (AT) has been extensively studied for various metabolic diseases such as obesity, type 2 diabetes, and immune system dysregulation due to its role in energy metabolism and regulation of inflammation. Physical activity is increasingly recognized as a powerful non-pharmacological tool for the treatment of various disorders, as it helps to improve metabolic, immune, and inflammatory functions. However, chronic excessive training has been associated with increased inflammatory markers and oxidative stress, so much so that excessive training overload, combined with inadequate recovery, can lead to the development of overtraining syndrome (OTS). OTS negatively impacts an athlete's performance capabilities and significantly affects both physical health and mental well-being. However, diagnosing OTS remains challenging as the contributing factors, signs/symptoms, and underlying maladaptive mechanisms are individualized, sport-specific, and unclear. Therefore, identifying potential biomarkers that could assist in preventing and/or diagnosing OTS is an important objective. In this review, we focus on the possibility that the endocrine functions of AT may have significant implications in the etiopathogenesis of OTS. During physical exercise, AT responds dynamically, undergoing remodeling of endocrine functions that influence the production of adipokines involved in regulating major energy and inflammatory processes. In this scenario, we will discuss exercise about its effects on AT activity and metabolism and its relevance to the prevention and/or development of OTS. Furthermore, we will highlight adipokines as potential markers for diagnosing OTS.

Vitamin D deficiency contributes to overtraining syndrome in excessive trained C57BL/6 mice.

Overtraining syndrome is a condition resulting from excessive training load associated with inadequate recovery and poor sleep quality, leading to performance decrements and fatigue. Here we hypothesized that vitamin D (VitD) deficiency is a lead factor in the development of the overtraining syndrome. To test this hypothesis, two groups of 60-week-old C57BL/6 mice followed a 16-week excessive eccentric-based overtraining by excessive downhill running with or without dietary VitD depletion (EX and EX-D- groups). Two control groups were trained by uphill running at the same load with or without VitD depletion (CX and CX-D- groups). Handgrip strength decreased throughout the protocol for all groups but the decrease was sharper in EX-D- group (VitD × training, p = 0.0427). At the end of the protocol, the mass of Triceps brachii muscle, which is heavily stressed by eccentric contractions, was reduced in eccentric-trained groups (training effect, p = 0.0107). This atrophy was associated with a lower concentration of the anabolic myokine IL-15 (training effect, p = 0.0314) and a tendency to a higher expression of the atrogene cathepsin-L (training effect, p = 0.0628). VitD depletion led to a 50% decrease of the fractional protein synthesis rate in this muscle (VitD effect, p = 0.0004) as well as decreased FGF21 (VitD effect, p = 0.0351) and increased osteocrin (VitD effect, p = 0.038) concentrations that would lead to metabolic defects. Moreover, the proportion of anti-inflammatory Th2 lymphocytes was significantly decreased by the combination of eccentric training with VitD depletion (vitD × training, p = 0.0249) suggesting a systemic inflammation. Finally, exploratory behavior time of mice was decreased by VitD depletion (VitD effect, p = 0.0146) suggesting a cognitive dysfunction. Our results suggest that VitD deficiency exacerbates the effects of overtraining.

The Potential of Heart Rate Variability Monitoring for Mental Health Assessment in Top Wheel Gymnastics Athletes: A Single Case Design.

The assessment of heart rate variability (HRV) upon waking has been proposed as a method to evaluate mental health; however, owing to large individual differences among athletes, it is unclear whether HRV is adequate to predict mental health decline. In this study, we sought to establish this by evaluating HRV upon awakening in one athlete over 20 months. We assessed mental health once a month by calculating the depression index. In addition, self-reported training load and psychological fatigue index were assessed as psychological indices for athletes. Heart rate and HRV were each measured three days per week in both resting (supine) and standing (upright) positions. The results showed that orthostatic HRV upon waking had moderate linear relationships with the scores on the depression index and psychological fatigue index. By contrast, self-reported training load, a measure of physical stressor, was not associated with HRV. The findings suggest that the repeated assessment of HRV upon waking and mental health indicators may be useful in preventing mental health decline in athletes.

Overtraining Syndrome as a Risk Factor for Bone Stress Injuries among Paralympic Athletes.

Background and Objectives: In this review, we have explored the relationship between overtraining syndrome (OTS) and bone stress injuries among paralympic athletes. OTS is a complex condition that arises from an imbalance between training volume, nutrition, and recovery time, leading to significant negative effects on paralympic athlete's performance and overall well-being. On the other hand, bone stress injuries occur when abnormal and repetitive loading is applied to normal bone, resulting in microdamage accumulation and potential. The prevalence of overtraining syndrome and bone stress injuries among athletes highlights the need for a better understanding of their relationship and implications for prevention and management strategies. Methods: A literature review from the PubMed, Web of Science, and Google Scholar databases including the MeSH keywords "overtraining syndrome", "bone", and "paralympic athletes". Results: Studies have consistently shown that athletes engaged in endurance sports are particularly susceptible to overtraining syndrome. The multifactorial nature of this condition involves not only physical factors, but also psychological and environmental determinants. In addition, the diagnosis and management of OTS and bone stress injuries present challenges in clinical practice. Conclusions: Currently, there are no definitive biochemical markers for overtraining syndrome. The diagnosis is based on a combination of subjective measures such as questionnaires, symptoms checklists, and objective biomarkers, including hormone levels, inflammatory markers, and imaging studies. However, these diagnostic approaches have limitations regarding their specificity and sensitivity.

Co-Operative Design of a Coach Dashboard for Training Monitoring and Feedback.

Athlete development depends on many factors that need to be balanced by the coach. The amount of data collected grows with the development of sensor technology. To make data-informed decisions for training prescription of their athletes, coaches could be supported by feedback through a coach dashboard. The aim of this paper is to describe the design of a coach dashboard based on scientific knowledge, user requirements, and (sensor) data to support decision making of coaches for athlete development in cyclic sports. The design process involved collaboration with coaches, embedded scientists, researchers, and IT professionals. A classic design thinking process was used to structure the research activities in five phases: empathise, define, ideate, prototype, and test phases. To understand the user requirements of coaches, a survey (n = 38), interviews (n = 8) and focus-group sessions (n = 4) were held. Design principles were adopted into mock-ups, prototypes, and the final coach dashboard. Designing a coach dashboard using the co-operative research design helped to gain deep insights into the specific user requirements of coaches in their daily training practice. Integrating these requirements, scientific knowledge, and functionalities in the final coach dashboard allows the coach to make data-informed decisions on training prescription and optimise athlete development.

Effects of different lengths of high-intensity interval training microcycles on the systemic and hippocampal inflammatory state and antioxidant balance of immature rats.

There is a lack of evidence on the effects of high-intensity interval training (HIIT) microcycle duration on the antioxidant capacity and hippocampal inflammatory response of young (immature) samples. This study compared two HIIT microcycles lengths on adaptation to training, antioxidant balance, and systemic and hippocampal inflammation in immature rats. Twenty-four immature Wistar rats (27 days) were equally divided into groups: control; 4-day HIIT (3 training days + 1 rest day); and 7-day HIIT (6 training days + 1 rest day). Both microcycles of 4 and 7 days were 28 days of training (37-38 m min-1). Running performance improved in all training groups compared to controls (P < 0.05). However, the 7-day HIIT group statistically increased serum interleukin-6 (IL-6) compared to the control and 4-day HIIT groups (P < 0.05). The total serum antioxidant capacity in the 7-day HIIT group was statistically lower than in the control group (P < 0.05). There was no statistical difference for the analysis of serum malondialdehyde between the groups. The hippocampal gene expression of IL-6, IL-1ß, IL-10, and tumor necrosis factor-alpha in the training groups was statistically higher than in the control group (P = 0.01), with no significant difference between the 4-day HIIT and 7-day HIIT groups. We concluded that HIIT microcycles with a longer duration decrease the antioxidant capacity and increase the systematic and hippocampal inflammation. Thus, we suggest using short HIIT microcycles for young (immature) groups due to improved running performance with less inflammatory and antioxidant changes.

Frequent blood flow restricted training not to failure and to failure induces similar gains in myonuclei and muscle mass.

The purpose of the present study was to compare the effects of short-term high-frequency failure vs non-failure blood flow-restricted resistance exercise (BFRRE) on changes in satellite cells (SCs), myonuclei, muscle size, and strength. Seventeen untrained men performed four sets of BFRRE to failure (Failure) with one leg and not to failure (Non-failure; 30-15-15-15 repetitions) with the other leg using knee-extensions at 20% of one repetition maximum (1RM). Fourteen sessions were distributed over two 5-day blocks, separated by a 10-day rest period. Muscle samples obtained before, at mid-training, and 10-day post-intervention (Post10) were analyzed for muscle fiber area (MFA), myonuclei, and SC. Muscle size and echo intensity of m.rectus femoris (RF) and m.vastus lateralis (VL) were measured by ultrasonography, and knee extension strength with 1RM and maximal isometric contraction (MVC) up until Post24. Both protocols increased myonuclear numbers in type-1 (12%-17%) and type-2 fibers (20%-23%), and SC in type-1 (92%-134%) and type-2 fibers (23%-48%) at Post10 (p < 0.05). RF and VL size increased by 5%-10% in both legs at Post10 to Post24, whereas the MFA of type-1 fibers in Failure was decreased at Post10 (-10 ± 16%; p = 0.02). Echo intensity increased by ~20% in both legs during Block1 (p < 0.001) and was ~8 to 11% below baseline at Post24 (p = 0.001-0.002). MVC and 1RM decreased by 5%-10% after Block1, but increased in both legs by 6%-11% at Post24 (p < 0.05). In conclusion, both short-term high-frequency failure and non-failure BFRRE induced increases in SCs, in myonuclei content, muscle size, and strength, concomitant with decreased echo intensity. Intriguingly, the responses were delayed and peaked 10-24 days after the training intervention. Our findings may shed light on the mechanisms involved in resistance exercise-induced overreaching and supercompensation.

The effect of chronic supplementation of Nigella sativa on splenocytes response in rats following treadmill exercise.

Nigella sativa (N. sativa) was shown to recover fatigue and imbalanced immune system. Therefore, effect of chronic administration of N. sativa hydroethanolic extract on splenocytes response in sedentary and exercised animals, was evaluated. Male Wistar rats were randomly divided into non-treated (control sedentary (C), moderately trained (MT; Velocity 20 m/min, 30 min/day 8 weeks), and over-trained (OT; Velocity 25 m/min, 60 min/day 11 weeks)), and N. sativa-treated animals (Nisa, 200 mg/kg, orally) (control (Nisa-C), moderately trained (Nisa-MT) and over-trained (Nisa-OT)). Finally, cell viability and proliferation, as well as interleukin 4 (IL-4) and interferon-γ (IFN-γ) secretion in non-stimulated and concanavalin A (Con A)-stimulated splenocytes, were evaluated. In the absence of the mitogen, cell viability in Nisa-C and Nisa-OT, cell proliferation in Nisa-C and Nisa-MT, IFN-γ concentration in Nisa-MT and Nisa-OT and IFN-γ/IL-4 ratio in Nisa C, Nisa-MT and Nisa-OT were higher compared to non-treated groups; but, IL-4 level in Nisa-MT was lower than non-treated groups. In the presence of the mitogen, cell viability in Nisa-C and Nisa-OT, IL-4 concentration in Nisa-C and Nisa-OT groups, and IFN-γ concentration and IFN-γ/IL-4 ratio in Nisa-MT were higher, while IFN-γ/IL-4 ratio was lower in Nisa-C group compared to non-treated groups. Moreover, IFN-γ/IL-4 ratio in stimulated and non-stimulated splenocytes supernatant was higher in Nisa-MT compared to Nisa-C and Nisa-OT groups. N. sativa chronic administration may shift Th1/Th2 cytokines profile of splenocytes towards Th1, especially in over-trained and non-stimulated condition. Moderate exercise and N. sativa supplementation may improve disorders associated with elevated Th2 such as overtraining syndrome.

Reliability of salivary cortisol and testosterone to a high-intensity cycling protocol to highlight overtraining.

Athletes physically overload to improve performance. Unbalanced stress/recovery may induce overtraining, which is difficult to diagnosis as no diagnostic marker exists. Hormonal responses to a 55/80 cycle (30-min of alternating blocks of 1-min at 55% and 4-min at 80% maximum work rate) may highlight early-stage overtraining (overreaching), as blunted cortisol and testosterone responses to 55/80 follows intensified training. However, the reliability of hormonal responses to 55/80 when not overreached is unknown. Therefore, reported blunted hormonal responses could be due to inconsistent cortisol and testosterone responses to 55/80. Participants (n = 23) completed three 55/80 bouts, >7 days apart, with no exercise 24 h pre-trials. Pre-exercise urine osmolality and stress questionnaire responses were measured. Pre, post, and 30-min post-exercise saliva samples were collected for cortisol and testosterone assessment. Salivary cortisol and testosterone responses, osmolality and well-being were not different between trials. Salivary cortisol and testosterone elevated from pre- to post-exercise [by 4.2 nmol.L-1 (cortisol) and 307 pmol.L-1 (testosterone)], and 30 min post-exercise [by 160 pmol.L-1 (testosterone) only]. Intraclass correlation coefficients for pre to peak post-exercise cortisol (0.89; good) and testosterone (0.53; moderate) were calculated. This demonstrates that 55/80 induces reliable elevations of salivary cortisol and testosterone when in a healthy state.

Quantitative but Not Qualitative Performance Changes in Predictive Motor Timing as a Result of Overtraining.

The possibilities of substantial long-term improvement of predictive timing might be sometimes seen as limited, with scanty information of neural substrates underlying the potential learning process. To address this issue, we have investigated the performance of 21 baseball professionals and 21 matched controls in a predictive motor timing task previously shown to engage the cerebellum. Baseball players, hypothesized as a model of overtraining of the prediction of future state of the surroundings, showed significantly higher quantitative performance than nonathletic controls, with a substantial part of the baseball players reaching levels far beyond the range observed in common population. Furthermore, the qualitative performance profile of baseball players under various conditions as target speed and acceleration modes did not differ from the profile of healthy controls. Our results suggest that regular exigent training has the potential to vastly improve predictive motor timing. Moreover, the quantitative but not qualitative difference in the performance profile allows us to hypothesize that the selective honing of the same cerebellar processes and networks as in non-trained individuals is the substrate for the quantitative performance improvement, without substantial engagement of further neural nodes.

Mental health issues and psychological factors in athletes: detection, management, effect on performance and prevention: American Medical Society for Sports Medicine Position Statement-Executive Summary.

The American Medical Society for Sports Medicine convened a panel of experts to provide an evidence-based, best practices document to assist sports medicine physicians and other members of the athletic care network with the detection, treatment and prevention of mental health issues in competitive athletes. This statement discusses how members of the sports medicine team, including team physicians, athletic trainers and mental health providers, work together in providing comprehensive psychological care to athletes. It specifically addresses psychological factors in athletes including personality issues and the psychological response to injury and illness. The statement also examines the athletic culture and environmental factors that commonly impact mental health, including sexuality and gender issues, hazing, bullying, sexual misconduct and transition from sport. Specific mental health disorders in athletes, such as eating disorders/disordered eating, depression and suicide, anxiety and stress, overtraining, sleep disorders and attention-deficit/hyperactivity disorder, are reviewed with a focus on detection, management, the effect on performance and prevention. This document uses the Strength of Recommendation Taxonomy to grade level of evidence.

Overreaching and overtraining in strength sports and resistance training: A scoping review.

To date, little is known about overreaching (OR) and the overtraining syndrome (OTS) in strength sports and resistance training (RT) populations. However, the available literature may elucidate the occurrence of both conditions in these populations. A scoping review was conducted. SPORTDiscus, Scopus and Web of Science were searched in a robust and systematic manner, with relevant articles analysed. 1170 records were retrieved during an initial search, with a total of 47 included in the review. Two broad themes were identified during data extraction: 1) overreaching in strength sports; 2) overreaching and overtraining syndrome in RT. Short-term periods of OR achieved with either high-volume or high-intensity RT can elicit functional OR (FOR) but there is also evidence that chronic high-volume and/or intensity RT can lead to non-functional overreaching (NFOR). There is minimal evidence to suggest that true OTS has occurred in strength sports or RT based on the studies entered during this review. More research is needed to develop robust guiding principles for practitioners. Additionally, due to the heterogeneous nature of the existing literature, future research would benefit from the development of practical tools to identify and diagnose the transition from FOR to NFOR, and subsequently OTS in strength athletes and RT populations. ABBREVIATIONS: RT: Resistance training; OR: Overreaching; FOR: Functional overreaching; NFOR: Non-functional overreaching; OTS: Overtraining syndrome; WP: Weightlifting performance.

Moderate, but Not Excessive, Training Attenuates Autophagy Machinery in Metabolic Tissues.

The protective effects of chronic moderate exercise-mediated autophagy include the prevention and treatment of several diseases and the extension of lifespan. In addition, physical exercise may impair cellular structures, requiring the action of the autophagy mechanism for clearance and renovation of damaged cellular components. For the first time, we investigated the adaptations on basal autophagy flux in vivo in mice's liver, heart, and skeletal muscle tissues submitted to four different chronic exercise models: endurance, resistance, concurrent, and overtraining. Measuring the autophagy flux in vivo is crucial to access the functionality of the autophagy pathway since changes in this pathway can occur in more than five steps. Moreover, the responses of metabolic, performance, and functional parameters, as well as genes and proteins related to the autophagy pathway, were addressed. In summary, the regular exercise models exhibited normal/enhanced adaptations with reduced autophagy-related proteins in all tissues. On the other hand, the overtrained group presented higher expression of Sqstm1 and Bnip3 with negative morphological and physical performance adaptations for the liver and heart, respectively. The groups showed different adaptions in autophagy flux in skeletal muscle, suggesting the activation or inhibition of basal autophagy may not always be related to improvement or impairment of performance.

Ketone ester supplementation blunts overreaching symptoms during endurance training overload.

KEY POINTS: Overload training is required for sustained performance gain in athletes (functional overreaching). However, excess overload may result in a catabolic state which causes performance decrements for weeks (non-functional overreaching) up to months (overtraining). Blood ketone bodies can attenuate training- or fasting-induced catabolic events. Therefore, we investigated whether increasing blood ketone levels by oral ketone ester (KE) intake can protect against endurance training-induced overreaching. We show for the first time that KE intake following exercise markedly blunts the development of physiological symptoms indicating overreaching, and at the same time significantly enhances endurance exercise performance. We provide preliminary data to indicate that growth differentiation factor 15 (GDF15) may be a relevant hormonal marker to diagnose the development of overtraining. Collectively, our data indicate that ketone ester intake is a potent nutritional strategy to prevent the development of non-functional overreaching and to stimulate endurance exercise performance. ABSTRACT: It is well known that elevated blood ketones attenuate net muscle protein breakdown, as well as negate catabolic events, during energy deficit. Therefore, we hypothesized that oral ketones can blunt endurance training-induced overreaching. Fit male subjects participated in two daily training sessions (3 weeks, 6 days/week) while receiving either a ketone ester (KE, n = 9) or a control drink (CON, n = 9) following each session. Sustainable training load in week 3 as well as power output in the final 30 min of a 2-h standardized endurance session were 15% higher in KE than in CON (both P < 0.05). KE inhibited the training-induced increase in nocturnal adrenaline (P < 0.01) and noradrenaline (P < 0.01) excretion, as well as blunted the decrease in resting (CON: -6 ± 2 bpm; KE: +2 ± 3 bpm, P < 0.05), submaximal (CON: -15 ± 3 bpm; KE: -7 ± 2 bpm, P < 0.05) and maximal (CON: -17 ± 2 bpm; KE: -10 ± 2 bpm, P < 0.01) heart rate. Energy balance during the training period spontaneously turned negative in CON (-2135 kJ/day), but not in KE (+198 kJ/day). The training consistently increased growth differentiation factor 15 (GDF15), but ∼2-fold more in CON than in KE (P < 0.05). In addition, delta GDF15 correlated with the training-induced drop in maximal heart rate (r = 0.60, P < 0.001) and decrease in osteocalcin (r = 0.61, P < 0.01). Other measurements such as blood ACTH, cortisol, IL-6, leptin, ghrelin and lymphocyte count, and muscle glycogen content did not differentiate KE from CON. In conclusion, KE during strenuous endurance training attenuates the development of overreaching. We also identify GDF15 as a possible marker of overtraining.

The effects of training on hormonal concentrations in young soccer players.

To test the hypothesis that football training would be accompanied by physiological adaptations and hormonal changes, we analyzed the effects of a whole football season on physical fitness and hormonal concentrations in youth football players. Male football players (n = 29, age 16.51 ± 0.7 years) in a regional professional league and male healthy control subjects (n = 30, age 17.1 ± 1 years) participated to the study. Blood cortisol, testosterone, and growth hormone (hGH) concentrations were assayed before the beginning of the training period (T0), just after the training period (T1), at the middle of the season (T2), and at the end of the season (T3). In each period physical tests and anthropometric measurements were also performed. Results showed significant differences in basal values of cortisol, testosterone, and growth hormone (hGH) in the four time points evaluated (P < 0.01). In addition, the concentrations of hGH were higher in the soccer players group than in control subjects (P < 0.001). Between the start of the training period and the end of the football season significant differences were observed in the anthropometric characteristics and in the physical form of the football players. Furthermore, the hormonal status was significantly correlated with the indicators of the lower limb power (squat-jump [SqJ], and counter-movement-jump [CMJ]) and those of aerobic performance (Yo-Yo intermittent recovery test level 1 (YYIRT1) and maximal oxygen consumption (VO2max )).These data underscore the importance of establishing training protocols that present the potential to promote positive adaptations without, at the same time, provoking overtraining of young players.

The proinflammatory effects of chronic excessive exercise.

Chronic moderate-intensity exercise is an efficient non-pharmacological strategy to prevent and treat several diseases such as type 2 diabetes mellitus, cardiovascular and chronic obstructive pulmonary diseases, cancers, and Parkinson's disease. On the other hand, improving an athlete's performance requires completing high-intensity and volume exercise sessions. When the delicate balance between high-load exercise sessions and adequate recovery periods is disrupted, excessive training (known as overtraining) can lead to performance decline. The cytokine hypothesis considers that an imbalance involving excessive exercise and inadequate recovery induces musculoskeletal trauma, increasing the production and release of proinflammatory cytokines, mainly interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and interleukin 1beta (IL-1beta), which interact with different organic systems, initiating most of the signs and symptoms linked to performance decrement. This leading article used recent data to discuss the scientific basis of Smith's cytokine theory and highlighted that the adverse effects of excessive exercise go beyond performance decline, proposing a multi-organ approach for this issue. These recent insights will allow coaches and exercise physiologists to develop strategies to avoid chronic excessive exercise-induced adverse outcomes.

Silibinin Alleviates the Learning and Memory Defects in Overtrained Rats Accompanying Reduced Neuronal Apoptosis and Senescence.

Excessive physical exercise (overtraining; OT) increases oxidative stress and induces damage in multiple organs including the brain, especially the hippocampus that plays an important role in learning and memory. Silibinin, a natural flavonoid derived from milk thistle of Silybum marianum, has been reported to exert neuroprotective effect. In this study, rats were subjected to overtraining exercise, and the protective effects of silibinin were investigated in these models. Morris water maze and novel object recognition tests showed that silibinin significantly attenuated memory defects in overtrained rats. At the same time, the results of Nissl, TUNEL and SA-ß-gal staining showed that silibinin reversed neuronal loss caused by apoptosis, and delayed cell senescence of the hippocampus in the overtrained rats, respectively. In addition, silibinin decreased malondialdehyde (MDA) levels which is associated with reactive oxygen species (ROS) generation. Silibinin prevented impairment of learning and memory caused by excessive physical exercise in rats, accompanied by reduced apoptosis and senescence in hippocampus cells.

Clinical and biochemical characteristics of high-intensity functional training (HIFT) and overtraining syndrome: findings from the EROS study (The EROS-HIFT).

The metabolic and hormonal consequences of high-intensity functional training regimens such as CrossFit® (CF) are unclear. Little is known about the triggers and clinical and biochemical features of CF-related overtraining syndrome (OTS). The EROS study compared endocrine and metabolic responses, and eating, social, psychological and body characteristics of OTS-affected (OTS) and healthy athletes (ATL), and non-physically active controls (NPAC). The current study is a post-hoc analysis of the CF subgroups of the EROS study, to evaluate specific characteristics of CF in ATL and OTS. Parameters were overall and pairwise compared among OTS-affected (CF-OTS) and healthy (CF-ATL) athletes that exclusively practiced CF, and NPAC. CF-ATL yielded earlier and enhanced cortisol, GH, and prolactin responses to an insulin tolerance test (ITT), increased neutrophils, lower lactate, increased testosterone, improved sleep quality, better psychological performance, increased measured-to-predicted basal metabolic rate (BMR) ratio and fat oxidation, and better hydration, when compared to NPAC. Conversely, more than 90% of the adaptive changes in CF were lost under OTS, including an attenuation of the hormonal responses to an ITT, increased estradiol, decreased testosterone, and decreased BMR and fat oxidation; the most remarkable trigger of OTS among "HIFT athletes" was the long-term low carbohydrate and calorie intake.