Peripheral signals of energy homeostasis as possible markers of training stress in athletes: a review

The Influence of an Intense Training Regime in Professional and Non-Professional Athletes on Semen Parameters: A Systematic Review

Background/Objectives: Male infertility is influenced by physiological factors like age, as well as lifestyle factors, including physical activity. However, the specific impact of sport activity on semen parameters, and thus on male fertility, remains unclear. Specifically, the aim of this systematic review is to evaluate how an intense regime of training may affect sperm parameters in professional and non-profession athletes. Methods: Studies reporting sperm parameters associated with high training load were included. In April 2024, three electronic databases and literature sources (PubMed, Scopus, and Web of Science) were searched. Quality appraisal was performed independently by three authors using the National Heart, Lung, and Blood Institute Quality Assessment Tools (NHLBI-QAT). Results: Four studies met the inclusion criteria, reporting a total of 156 participants. Sixteen weeks of intensive cycling training produced a significant decrease in seminal volume, sperm concentration, sperm motility, and morphology, with a return to their initial levels, except for sperm morphology and sperm concentration, after at least one week of rest. In addition, in athletes with varicocele, a 6-month stop from sports activity went a long way toward improving sperm concentration and sperm motility. However, DNA fragmentation, a greater presence of round cells, and high numbers of active macrophages were described. At least 30 days improve semen parameters in professional and non-professional athletes. Conclusions: Intensive training could worsen seminal parameters and, consequently, male fertility. However, certainty of evidence is very low, and the results should be interpreted with caution.

Exercise Immunology Applied to Pediatric Sport and the Importance of Monitoring Stages of Puberty and Biological Maturation

CONTEXT

Exercise immunology is aimed at understanding how exercise sessions can affect the immune system in athletic subjects of different age groups. The objective of the current study was to discuss in which stage of biological maturation (BM) young athletes may be more vulnerable in relation to the immune system, and whether there is a BM range in which it is safer to perform sports training with strenuous exercise loads.

EVIDENCE ACQUISITION

Evidence from scientific research from several scientific disciplines (eg, immunology, sport immunology, pediatrics, sports medicine, human development) was gathered to holistically examine the main particularities of exercise immunology as applied to pediatric sport.

STUDY DESIGN

Narrative review.

LEVEL OF EVIDENCE

Level 5.

RESULTS

In pediatric patients, lymphoid tissue expands during puberty and involutes after puberty until it returns to pre-expansion values. This suggests that there is a specific period in which the immune system may be stronger, which may provide opportunities for strenuous exercise in pediatric athletes. However, the chronological period when puberty occurs will be determined by BM, which is the rate at which the biological systems of the human body improves. This may affect the period of lymphoid tissue expansion and, consequently, the behavior of the immune system in pediatric subjects of the same age category.

CONCLUSION

During puberty, there is a significant increase in the proinflammatory profile; to compensate for this, there is an expansion of lymphoid tissue that may favor the efficiency of the immune system. The period in which puberty is reached may vary according to the stages of BM. Therefore, in exercise immunology applied to pediatric sports, in addition to external and internal training loads, it is necessary to consider BM and puberty, which have been shown to be safer biomarkers than chronological age for determining immune system behavior in pediatric athletes.

STRENGTH-OF-RECOMMENDATION TAXONOMY (SORT)

Evidence B level 3.

The extraordinary "ordinary magic" of resilience

In this essay, I will briefly sample different instances of the utilization of the concept of resilience, attempting to complement a comprehensive representation of the field in the special issue of Development and Psychopathology inspired by the 42nd Minnesota Symposium on Child Psychology, hosted by the Institute of Child Development at the University of Minnesota and held in October of 2022. Having established the general context of the field, I will zoom in on some of its features, which I consider "low-hanging fruit" and which can be harvested in a systematic way to advance the study of resilience in the context of the future of developmental psychopathology.

The Effect of Endurance Exercise on Semen Quality in Male Athletes: A Systematic Review

BACKGROUND

Endurance exercise has the potential to affect reproductive function, with amenorrhea in female athletes. However, most studies focus on women. Evidence on the association between endurance exercise and male fertility is limited.

OBJECTIVE

To synthesise existing literature on exercise-induced alterations in semen parameters and to assess the clinical impact on male fertility.

METHODS

Studies reporting on the association between semen parameters and endurance exercise in healthy men were eligible. Men attending fertility clinics were excluded. We searched MEDLINE (PubMed), Embase, SPORTDiscus, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov and International Clinical Trials Registry Platform (ICTRP) from their inception to May 28th 2022. JBI Critical Appraisal Tool was used to assess the potential risk of bias.

RESULTS

Thirteen studies met inclusion criteria, reporting on 280 subjects. Eight articles reported on endurance runners, three on cyclists and four on triathletes. Four studies did not find any statistically significant sperm alterations. Five reported significant changes in semen parameters, but these were not clinically relevant, as semen parameters remained well above World Health Organisation (WHO) thresholds. Four articles reported a decrease in semen quality with potential clinical consequences as they found a reduced number of sperm cells exhibiting normal morphology in cyclists and triathletes and a greater amount of DNA fragmentation in triathletes.

CONCLUSION

Endurance exercise can have a negative effect on semen quality, although rarely with a clinically relevant impact on male fertility. Evidence is however limited, with poor quality of the included studies.

REGISTRATION

PROSPERO International prospective register of systematic reviews (CRD42022336753).

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.

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.

The Association of Serum Calprotectin with Fitness Indicators and Biochemical Markers in High-Level Athletes: A Continuous Dynamic Monitoring during One Competitive Season

The objective was to determine the associations between several biochemical indicators and the dynamics of concentration change across four physical fitness phases over the period of a competitive season. Furthermore, associations between serum calprotectin and biomarkers of inflammation or muscle injury and physical indicators were examined.

SUBJECTS AND METHODS

Twenty professional male water polo players (median age: 28 (22-42)) were included in this study. Serum creatine kinase activity was determined by the automated photometric UV method. The concentrations of calprotectin, C-reactive protein, and myoglobin were measured using an automated immunoturbidimetric method, while an automated immunochemistry method was employed for interleukin-6, troponin I, and cortisol determination. Tests of repeated strength, maximal strength, and static strength were used to evaluate physical activity.

RESULTS

Serum calprotectin concentrations expressed in median and IQR were significantly different: T1: 2.92 g/mL (2.47; 3.86); T2: 2.35 g/mL (1.26; 2.87); T3: 2.27 g/mL (1.60; 3.27); and T4: 1.47 g/mL (1.04; 2.85) (p = 0.004). Cortisol concentration and CK activity showed significant changes among phases (p = 0.049 and p = 0.014, respectively). Each physical activity examined showed a significant seasonal decrease (all p values were 0.001). Calprotectin serum concentration and indicators of muscular injury, inflammation, and physical activity were found to be correlated during particular stages of the seasonal examination.

CONCLUSIONS

Calprotectin values determined throughout one competitive season decreased as training intensity among water polo players increased. Serum calprotectin concentrations and indicators were related to biochemical markers of inflammation and muscle damage.

Changes in irisin, inflammatory cytokines and aerobic capacity in response to three weeks of supervised sprint interval training in older men

BACKGROUND

This study investigated the effects of supervised short-term sprint interval training (SIT) on circulating irisin, interleukin (IL)-6 and tumour necrosis factor (TNF)-α concentrations, and aerobic capacity and body composition values in healthy older men.

METHODS

Eleven older men (63±8 years; 178.0±5.5 cm; 82.7±8.6 kg; 22.7±3.7% body fat) underwent SIT (6 repetitions of 30 s all-out cycling bouts with 4 min active recovery after each bout) three days a week for three consecutive weeks. Body composition measured by dual-energy X-ray absorptiometry, aerobic capacity assessed by direct peak oxygen consumption (VO<inf>2peak</inf>) test and morning fasting blood samples were obtained before and after a 3-week SIT intervention.

RESULTS

Nine supervised SIT sessions moderately (effect size [ES] =0.65; P<0.05) increased irisin concentrations (from 135.40±28.73 to 154.20±47.09 ng.mL^-1) together with moderate decreases (P<0.05) in IL-6 (ES=0.89; from 1.26±0.44 to 0.87±0.44 pg.mL^-1) and TNF-α (ES=0.64; from 5.10±1.23 to 4.31±1.20 pg.mL^-1) levels in older men. In addition, increase in VO<inf>2peak</inf> was significant but small (ES=0.25; P<0.05; from 36.0±7.1 to 37.8±6.7 mL.min.^-1kg^-1), while no changes (P>0.05) in body composition variables were observed after a short-term SIT period.

CONCLUSIONS

A 3-week SIT intervention with only nine training sessions increased circulating irisin concentrations, improved inflammatory profile and aerobic capacity without changes in body composition in healthy older men. Accordingly, a short-term SIT programme is a time efficient alternative for traditional aerobic training to improve metabolic health and aerobic capacity in older adults.

Associations of Circulating Irisin and Fibroblast Growth Factor-21 Levels with Measures of Energy Homeostasis in Highly Trained Adolescent Rhythmic Gymnasts

The aim of this investigation was to determine the associations of serum irisin and fibroblast growth factor-21 (FGF-21) with the measures of energy homeostasis, training stress and other energy homeostasis hormones in highly trained adolescent rhythmic gymnasts (RG). Thirty-three RG and 20 untrained controls (UC) aged 14−18 years participated in this study. Body composition, resting energy expenditure (REE), peak oxygen consumption, and different energy homeostasis hormones in serum, including irisin, FGF-21, leptin, and resistin, were measured. Irisin and FGF-21 were not significantly different (p > 0.05) between RG and UC groups. In RG, serum irisin was positively associated with REE (r = 0.40; p = 0.021) and leptin (r = 0.60; p = 0.013), while serum FGF-21 was related to body fat mass (r = 0.46; p = 0.007) and leptin (r = 0.45; p = 0.009). Irisin was related to FGF-21, independent of age, body fat, and lean masses (r = 0.36; p = 0.049) in RG. In conclusion, serum irisin concentration was associated with energy expenditure and serum FGF-21 level with energy availability measures in lean adolescent athletes, while no relationships of irisin and FGF-21 with energy status measures were observed in lean nonathletic adolescents.

Effects of 6-Week Supplementation with GliSODin on Parameters of Muscle Damages, Metabolic, and Work Performance at International Level Rowers after Specific Maximal Effort

This study aimed to investigate the effect of supplementation with plant origin superoxide dismutase (SOD), GliSODin, on parameters of muscle damage, metabolic, and work performance at international level rowers. Twenty-eight rowers were included in a randomized, double-blind study. The study was conducted during a 6-week preparation period. At the beginning of the study and after 6 weeks of the supplementation period, all rowers were tested on a rowing ergometer. Blood samples were taken from the antecubital vein before and after every ergometer testing. Muscle damage markers creatine kinase (CK) and lactate dehydrogenase (LDH), total antioxidant capacity (TAC), inflammation parameters interleukin-6 (IL-6), and C-reactive protein (CRP) were measured. Rowing performance was assessed by lactate level in capillary blood and power output on the rowing ergometer. After supplementation, experimental group had significantly lower CK (p = 0.049) and IL-6 (p = 0.035) before and IL-6 (p = 0.050) after exhausting exercise on ergometer. Relative change of power output at 4 mmol/L concentration of lactate in blood, considering the initial and final test, was significantly higher (p = 0.020) in the supplemented group. It was concluded that GliSODin could be considered a good supplement in preventing some deleterious effects of intensive physical activity, including inflammation and muscle damage, and consequently, to enable a better rowing performance of elite rowers.

Neuroendocrine, Inflammatory, and Extracellular Vesicle Responses During the Navy Special Warfare Screener Selection Course

BACKGROUND

Military operational stress is known to increase adrenal hormones and inflammatory cytokines, while decreasing hormones associated with the anabolic milieu and neuroendocrine system. Less is known about the role of extracellular vesicles (EVs), a form of cell-to-cell communication, in military operational stress and their relationship to circulating hormones.

PURPOSE

To characterize the neuroendocrine, cytokine, and EV response to an intense, 24-h selection course known as the Naval Special Warfare (NSW) Screener and identify associations between EVs and cytokines.

METHODS

Blood samples were collected the morning of and following the NSW Screener in 29 men (18 - 26 years). Samples were analyzed for concentrations of cortisol, insulin-like growth factor I (IGF-I), neuropeptide-Y (NPY), brain-derived neurotrophic factor (BDNF), α-klotho, tumor necrosis factor- α (TNFα), and interleukins (IL) -1β, -6, and -10. EVs stained with markers associated with exosomes (CD63), microvesicles (VAMP3), and apoptotic bodies (THSD1) were characterized using imaging flow cytometry and vesicle flow cytometry.

RESULTS

The selection event induced significant changes in circulating BDNF (-43.2%), IGF-I (-24.56%), TNFα (+17.7%), IL-6 (+13.6%), accompanied by increases in intensities of THSD1⁺ and VAMP3⁺ EVs (all p<0.05). Higher concentrations of IL-1β and IL-10 were positively associated with THSD1⁺ EVs (p<0.05).

CONCLUSION

Military operational stress altered the EV profile. Surface markers associated with apoptotic bodies were positively correlated with an inflammatory response. Future studies should consider a multi-omics assessment of EV cargo to discern canonical pathways that may be mediated by EVs during military stress.

Gut Microbiota and Serum Metabolome in Elite Cross-Country Skiers: A Controlled Study

Exercise has been shown to affect gut the microbiome and metabolic health, with athletes typically displaying a higher microbial diversity. However, research on the gut microbiota and systemic metabolism in elite athletes remains scarce. In this study, we compared the gut microbiota profiles and serum metabolome of national team cross-country skiers at the end of an exhausting training and competitive season to those of normally physically-active controls. The gut microbiota were analyzed using 16S rRNA amplicon sequencing. Serum metabolites were analyzed using nuclear magnetic resonance. Phylogenetic diversity and the abundance of several mucin-degrading gut microbial taxa, including Akkermansia, were lower in the athletes. The athletes had a healthier serum lipid profile than the controls, which was only partly explained by body mass index. Butyricicoccus associated positively with HDL cholesterol, HDL2 cholesterol and HDL particle size. The Ruminococcus torques group was less abundant in the athlete group and positively associated with total cholesterol and VLDL and LDL particles. We found the healthier lipid profile of elite athletes to co-occur with known health-beneficial gut microbes. Further studies should elucidate these links and whether athletes are prone to mucin depletion related microbial changes during the competitive season.

Circulating biomarkers associated with performance and resilience during military operational stress

Adaptation to military operational stress is a complex physiological response that calls upon the sympathetic nervous system (SNS), hypothalamic pituitary adrenal (HPA) axis and immune system, to create a delicate balance between anabolism and catabolism and meet the demands of an ever-changing environment. As such, resilience, the ability to withstand and overcome the negative impact of stress on military performance, is likely grounded in an appropriate biological adaptation to encountered stressors. Neuroendocrine [i.e. cortisol, epinephrine (EPI), norepinephrine (NE), neuropeptide-Y (NPY), and brain derived neurotropic factor (BDNF)], inflammatory [i.e. interleukin 6 (IL-6), IL-1β, IL-4, IL-10 and tumour necrosis factor (TNF)-α], as well as growth and anabolic [i.e. insulin-like growth factor-I (IGF-I), testosterone, and dehydroepiandrosterone (DHEA)] biomarkers independently and interactively function in stress adaptations that are associated with a soldier's physical and psychological performance. In this narrative review, we detail biomarkers across neuroendocrine, inflammatory, and growth stimulating domains to better elucidate the biological basis of a resilient soldier. The findings from the reviewed studies indicate that military readiness and resiliency may be enhanced through better homeostatic control, better regulated inflammatory responses, and balanced anabolic/catabolic processes. It is unlikely that one class of biomarkers is better for assessing physiological resilience. Therefore, a biomarker panel that can account for appropriate balance across these domains may be superior in developing monitoring frameworks. Real-time physiological monitoring to assess biomarkers associated with resilience will be possible pending more sophisticated technologies and provide a field-expedient application for early identification and intervention of at-risk soldiers to improve military resiliency.

Effect of Seasonal Variation during Annual Cyclist Training on Somatic Function, White Blood Cells Composition, Immunological System, Selected Hormones and Their Interaction with Irisin

The aim of this study was to evaluate somatic, hormonal and immunological changes during the macrocycle of cyclists (9 well-trained men, age 25.6 ± 5.2 years and body weight 72.4 ± 7.35 kg). During the training macrocycle, four exercise control tests were carried out, and biochemical markers were measured in the laboratory. Seasonal training changes did not significantly disturb resting somatic and functional parameters, physical capacity (VO2max), body weight, the number of leukocytes and selected hormones. The secretory system of the organism did not respond significantly to the exercise stress in the training process, even with the increasing share of anaerobic processes in the subsequent periods of the macrocycle. Irisin and other parameters globally did not correlate with training volume. Irisin showed a significant correlation only with cortisol in the first period and human growth hormone in the second, and it showed a weak correlation in the third period with body mass and BMI. The lack of interactions between irisin level and other variables practically excludes its use in monitoring cyclist training. Future research would be complemented by the assessment of stress and postexercise changes in the cyclists’ macrocycle and expanding the research group to other athletes, including women.

Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared Pathways, Symptoms and Complexities

The symptom similarities between training-overload (with or without an Overtraining Syndrome (OTS) diagnosis) and Relative Energy Deficiency in Sport (RED-S) are significant, with both initiating from a hypothalamic-pituitary origin, that can be influenced by low carbohydrate (CHO) and energy availability (EA). In this narrative review we wish to showcase that many of the negative outcomes of training-overload (with, or without an OTS diagnosis) may be primarily due to misdiagnosed under-fueling, or RED-S, via low EA and/or low CHO availability. Accordingly, we undertook an analysis of training-overload/OTS type studies that have also collected and analyzed for energy intake (EI), CHO, exercise energy expenditure (EEE) and/or EA. Eighteen of the 21 studies (86%) that met our criteria showed indications of an EA decrease or difference between two cohorts within a given study (n = 14 studies) or CHO availability decrease (n = 4 studies) during the training-overload/OTS period, resulting in both training-overload/OTS and RED-S symptom outcomes compared to control conditions. Furthermore, we demonstrate significantly similar symptom overlaps across much of the OTS (n = 57 studies) and RED-S/Female Athlete Triad (n = 88 studies) literature. It is important to note that the prevention of under-recovery is multi-factorial, but many aspects are based around EA and CHO availability. Herein we have demonstrated that OTS and RED-S have many shared pathways, symptoms, and diagnostic complexities. Substantial attention is required to increase the knowledge and awareness of RED-S, and to enhance the diagnostic accuracy of both OTS and RED-S, to allow clinicians to more accurately exclude LEA/RED-S from OTS diagnoses.

Irisin, Fibroplast Growth Factor-21, and Follistatin Responses to Endurance Rowing Training Session in Female Rowers

Purpose: This study examined selected myokine responses to an endurance rowing training session, and whether metabolic demands of the acute aerobic rowing exercise together with training volume, aerobic capacity, and body composition variables affect potential exercise-induced changes in the myokine levels in female rowers. Methods: Fifteen national level female rowers [18.3 ± 1.6 years; 172.0 ± 5.0 cm, 67.5 ± 8.8 kg; maximal oxygen consumption (VO₂max): 47.2 ± 7.9 ml.min.^-1 kg^-1] performed a 1-h rowing ergometer exercise at the intensity of 70% of VO₂max [distance: 12.1 ± 1.1 km; energy expenditure (EE): 639 ± 69 kcal; heart rate (HR): 151 ± 7 beats.min^-1] followed by a 30-min recovery period. Venous blood samples were collected before and after exercise, and analyzed for irisin, fibroplast growth factor-21 (FGF-21), and follistatin conentrations. Results: Plasma irisin and FGF-21 concentrations were increased (by 8%; p = 0.013 and by 13%; p < 0.0001, respectively) immediately after the aerobic rowing exercise. Follistatin was significantly increased (by 11%; p = 0.001) only after the first 30 min of recovery. Exercise metabolic demand variables such as distance covered and total EE were correlated with the pre-to-post-exercise increases in FGF-21 concentrations (r = 0.52; p = 0.047 and r = 0.68; p = 0.005, respectively). Exercise-induced increases in irisin levels were related to aerobic capacity as measured by VO₂max (r = 0.53; p = 0.041) and training stress as measured by weekly training volume (r = 0.54; p = 0.039) in female rowers. Conclusion: Acute negative energy balance induced by a single endurance rowing training session elicited significant increases in irisin, FGF-21, and follistatin levels in national level female rowers. While exercise-induced increases in FGF-21 levels were associated with exercise metabolic demand measures, exercise-induced increases in irisin concentrations were related to aerobic capacity and training stress measures in female rowers.

Decreased energy availability during training overload is associated with non-functional overreaching and suppressed ovarian function in female runners

Low energy availability (EA) suppresses many physiological processes, including ovarian function in female athletes. Low EA could also predispose athletes to develop a state of overreaching. This study compared the changes in ad libitum energy intake (EI), exercise energy expenditure (ExEE), and EA among runners completing a training overload (TO) phase. We tested the hypothesis that runners becoming overreached would show decreased EA, suppressed ovarian function and plasma leptin, compared with well-adapted (WA) runners. After 1 menstrual cycle (baseline), 16 eumenorrheic runners performed 4 weeks of TO followed by a 2-week recovery (131 ± 3% and 63 ± 6% of baseline running volume, respectively). Seven-day ExEE, EI, running performance (RUN_perf) and plasma leptin concentration were assessed for each phase. Salivary estradiol concentration was measured daily. Urinary luteinizing hormone concentration tests confirmed ovulation. Nine runners adapted positively to TO (WA, ΔRUN_perf: +4 ± 2%); 7 were non-functionally overreached (NFOR; ΔRUN_perf: -9 ± 2%) as RUN_perf remained suppressed after the recovery period. WA increased EI during TO, maintaining their baseline EA despite a large increase in ExEE (ΔEA = +1.9 ± 1.3 kcal·kg fat free mass (FFM)^-1·d^-1, P = 0.17). By contrast, NFOR showed no change in EI, leading to decreased EA (ΔEA = -5.6 ± 2.1 kcal·kg FFM^-1·d^-1, P = 0.04). Plasma leptin concentration mid-cycle and luteal salivary estradiol concentration decreased in NFOR only. Contrasting with WA, NFOR failed to maintain baseline EA during TO, resulting in poor performance outcomes and suppressed ovarian function. ClinicalTrials.gov no. NCT02224976. Novelty: Runners adapting positively to training overload (TO) increased ad libitum energy intake, maintaining baseline EA and ovarian function through TO. By contrast, NFOR runners failed to increase energy intake, showing suppressed EA and ovarian function during TO.

Associations between inflammatory markers and well-being during 12 weeks of basic military training

PURPOSE

Stress, anxiety and physical exertion are all closely linked to well-being, and each can alter immune function. Diminished well-being has been observed during military training, however there is mixed evidence regarding whether concomitant changes in inflammatory markers occur, with these phenomena indicating potential maladaptive responses to imposed training loads. The aims of this project were (1) assess changes in inflammation and subjective well-being across a 12-week basic military training (BMT) program, and (2) evaluate relationships between circulating inflammatory markers and well-being.

METHODS

A total of 37 men and women undergoing 12 weeks of BMT in Australia were recruited. Well-being was assessed via questionnaire (DASS-21), and plasma samples were collected for the analysis of inflammatory cytokines [interleukin (IL)-4, IL-6, IL-1β, IL-8, IL-10, and tumor necrosis factor (TNF)-α] at weeks 1, 4, 8 and 12. Data were analysed using general linear mixed models.

RESULTS

Depression, anxiety and stress subscale scores all significantly improved (all P ≤ 0.001), and TNF-α decreased (P = 0.031) across time. Compared to baseline (week 1), significant decreases in associations between depression and IL-10, anxiety and IL-10, and stress and IL-10, IL-4 IL-6 and TNF-α (all P < 0.05), were detected across BMT.

CONCLUSION

The BMT program appears to support improved well-being over the 12 weeks, with minimal perturbation to inflammatory markers. Biomarkers and well-being displayed consistent associations and may have utility as psychophysiological indicators of health status in military research, however for now, subjective measures may represent more cost-effective proxies for ongoing monitoring of military personnel.

Circulating Inflammatory Biomarkers and Endocrine Responses to Exercise in Female Soccer Players

The objective of the study to determine the effects of graded exercise on the cytokines and insulin-like growth factor-1 (IGF-1), growth hormone (hGH), testosterone (T), and cortisol (C) concentrations in the peripheral blood of female soccer players, and to evaluate if increased inflammatory biomarkers were related to these hormones and performance variables. Sixteen female soccer players (N = 16, age 19.3 ± 2.3 years) participated in this study. Blood samples were collected at three time points: pre-exercise, post-exercise, and in the 15th minute of recovery, to evaluate morphological and biochemical variables. The relative expression of IL-6 (interleukin 6) and serum concentrations of the cytokines were increased in the recovery period compared to pre-exercise levels (p = 0.03 and p=0.005, respectively). There was a significant effect of exercise on serum hGH level (p “ 0.001), T/C ratio (p = 0.001), and C level (p=0.02). Positive correlations were found between: post-exercise IL-1β (interleukin 1 beta) and IL-6 (R = 0.84, p = 0.000), and the IL-6 and TNF-α (tumor necrosis factor alpha) gene expression during recovery (R = 0.65, p = 0.009), and serum IL-1β post-exercise and maximal power (R = 0.68; p = 0.004). Exercise-induced serum C levels positively correlated with IGF-1 levels (R = 0.52 p = 0.05). Negative associations were revealed between post-exercise T/C ratio and IGF-1 (R = - 0.58, p = 0.03) and serum free T and IL- β (R = -0.56, p = 0.04) levels. The low level of pre-exercise genes and protein of the IL-1β, IL-6 and TNF-α indicate a lack of inflammation signs in the female soccer players. This study shows significant effects of exercise on hormone levels and pro-inflammatory markers, which could be used to identify the role of female sex steroids on the immune function.

Alterations in Adiponectin, Leptin, Resistin, Testosterone, and Cortisol across Eleven Weeks of Training among Division One Collegiate Throwers: A Preliminary Study

Cytokine and hormone concentrations can be linked to the manipulation of training variables and to subsequent alterations in performance.

SUBJECTS

Nine D-1 collegiate throwers and 4 control subjects participated in this preliminary and exploratory report.

METHODS

Hormone (testosterone (T) and cortisol (C)) and adipokine (adiponectin, leptin, and resistin) measurements were taken at weeks 1, 7, and 11 for the throwers and weeks 1 and 11 for the control group. The throwers participated in an 11-week periodized resistance training and throws program during the fall preparatory period. Volume load was recorded throughout the study.

RESULTS

Hormone values did not exhibit statistically significant changes across time; however, there were notable changes for C, the testosterone to cortisol ratio (T:C), and adiponectin.

CONCLUSIONS

T:C was increased as volume load decreased, and adiponectin increased in concert with decreases in C and increases in the T:C, possibly suggesting a lesser degree of obesity-related inflammation and a higher degree of "fitness" and preparedness.

Proteomic Profiling and Monitoring of Training Distress and Illness in University Swimmers During a 25-Week Competitive Season

Purpose

To evaluate relationships of proteomics data, athlete-reported illness, athlete training distress (TDS), and coaches’ ratings of distress and performance over the course of the competitive season.

Methods

Thirty-five NCAA Division II swimmers were recruited to the study (male n = 19, female n = 16; age 19.1 ± 1.6 years). Athletes provided fingerprick dried blood spot (DBS) samples, illness symptoms, and TDS every Monday for 19 of 25 weeks in their season. Coaches monitored performance and rated visual signs of distress. DBS samples were analyzed for a targeted panel of 12 immune-related proteins using liquid chromatography/mass spectrometry (LC/MS).

Results

Thirty-two swimmers completed the protocol. The data were grouped in 2–3 weeks segments to facilitate interpretation and analysis of the data. TDS scores varied between athletes, and were highest during the early fall conditioning ramp up period (8.9 ± 1.6 at baseline to a peak of 22.6 ± 2.0). The percent of athletes reporting illness was high throughout the season (50–78%). Analysis of TDS using Principle Component Analysis (PCA) revealed that 40.5% of the variance (PC1) could be attributed to illness prevalence, and TDS scores for the athletes reporting illness and no illness were different across the season (P < 0.001). The coaches’ ratings of swim performance and swimmer’s distress, sex, and racing distance (sprinters, middle distance, long distance) were not correlated with PC1. Linear Discriminant Analysis (LDA) analysis of the data showed a separation of the baseline weeks from exam weeks with or without competitions, and with competitions alone (p < 0.001). Seven of the 12 proteins monitored over the course of training were upregulated, and the addition of the protein data to LDA analysis enhanced the separation between these groups of weeks.

Conclusion

TDS and illness were related in this group of 32 collegiate swimmers throughout the competitive season, and expression of immune proteins improved the statistical separation of baseline weeks from the most stressful weeks. TDS data provided by the swimmers did not match their coaches’ ratings of distress and swim performance. The importance of the immune system in the reaction to internal and external stress in athletes should be an area of further research.

Sex differences in daily activity intensity and energy expenditure and their relationship to cortisol among BaYaka foragers from the Congo Basin

OBJECTIVES

The pooling of energetic resources and food sharing have been widely documented among hunter-gatherer societies. Much less is known about how the energetic costs of daily activities are distributed across individuals in such groups, including between women and men. Moreover, the metabolic physiological correlates of those activities and costs are relatively understudied.

MATERIALS AND METHODS

Here, we tracked physical activity, energy expenditure (EE), and cortisol production among Congo Basin BaYaka foragers engaged in a variety of daily subsistence activities (n = 37). Given its role in energy mobilization, we measured overall daily cortisol production and short-term cortisol reactivity through saliva sampling; we measured physical activity levels and total EE via the wGT3X-bt actigraph and heart rate monitor.

RESULTS

We found that there were no sex differences in likelihood of working in common activity locations (forest, garden, house). Across the day, women spent greater percentage time in moderate-to-vigorous physical activity (%MVPA) and had lower total EE than men. Females with higher EE (kCal/hr) produced greater cortisol throughout the day. Though not statistically significant, we also found that individuals with greater %MVPA had larger decreases in cortisol reactivity.

DISCUSSION

BaYaka women sustained higher levels of physical activity but incurred lower energetic costs than men, even after factoring in sex differences in body composition. Our findings suggest that the distribution of physical activity demands and costs are relevant to discussions regarding how labor is divided and community energy budgets take shape in such settings.

The Important Role of Adiponectin and Orexin-A, Two Key Proteins Improving Healthy Status: Focus on Physical Activity

Exercise represents the most important integrative therapy in metabolic, immunologic and chronic diseases; it represents a valid strategy in the non-pharmacological intervention of lifestyle linked diseases. A large body of evidence indicates physical exercise as an effective measure against chronic non-communicable diseases. The worldwide general evidence for health benefits are both for all ages and skill levels. In a dysregulated lifestyle such as in the obesity, there is an imbalance in the production of different cytokines. In particular, we focused on Adiponectin, an adipokine producted by adipose tissue, and on Orexin-A, a neuropeptide synthesized in the lateral hypothalamus. The production of both Adiponectin and Orexin-A increases following regular and structured physical activity and both these hormones have similar actions. Indeed, they improve energy and glucose metabolism, and also modulate energy expenditure and thermogenesis. In addition, a relevant biological role of Adiponectin and Orexin A has been recently highlighted in the immune system, where they function as immune-suppressor factors. The strong connection between these two cytokines and healthy status is mediated by physical activity and candidates these hormones as potential biomarkers of the beneficial effects induced by physical activity. For these reasons, this review aims to underly the interconnections among Adiponectin, Orexin-A, physical activity and healthy status. Furthermore, it is analyzed the involvement of Adiponectin and Orexin-A in physical activity as physiological factors improving healthy status through physical exercise.

Correlation between level of adipocytokines with body composition and heart rate recovery indices

Introduction: Adipose tissue as an endocrine organ primarily regulates metabolism of carbohydrates and lipids. Anorexigenic hormone leptin increases sympathetic activity and decreases insulin secretion, thereby reducing energy depots, while adiponectin elevates tissue sensitivity to insulin, which role visfatin imitates. Heart rate recovery index (DHRR), linked with insulin resistance syndrome, reflects parasympathetic function. Our goal was to analyze correlation between adipocytokines with body composition and DHRR in athletes and sedentary controls. Material and methods: Research included 19 volleyball and water polo national team members (mean age 19.26 ± 1.94 years) and 13 physically inactive male students (mean age 20.46 ± 1.13 years). Anthropometric data were measured and blood samples for hormone analysis were taken: at the beginning, the end and 30 minutes after finishing ergospirometry. Statistical evaluation was performed using: Student's t-test, Mann-Whitney, Wilcoxon's and Spearman's rank correlation test. Results: Adiponectin levels between dependent and independent variables didn't show statistical significance. Leptin level, noteworthy lower in athletes, at the beginning and the end of the test (p < 0.001 and p = 0.001, respectively), was declining in students in every before-after study aspect (p < 0.001 in each case). Visfatin was higher in sportsmen at the end of the test and 30 minutes later (p < 0.001 in both cases), but their levels decreased comparing the beginning and 30 minutes after the test (p = 0.02). Body height, VO2 max and DHRR3 were considerably higher in athletes, just as BMI, BF% and HR in the third minute of recovery were in controls (p < 0.05). Sportsmen had moderately strong negative correlation of visfatin with BF% (p = 0.002, RS = -0.674), whilst leptin showed moderately strong positive correlation with BMI and BF% (p = 0.002, RS = -0.657 and p = 0.011, RS = 0.567), respectively. Controls demonstrated strong and moderately strong positive correlation between leptin with DHRR1 (p = 0.008, RS = 0.702) and DHRR3 (p = 0.018, RS = 0.641), respectively. Conclusion: Research showed positive correlation between visfatin with BF% and leptin with BMI and BF% in athletes, considering small number of participants.

Oxidative stress in exercise training: the involvement of inflammation and peripheral signals

The evidence about the health benefits of regular physical activity is well established. Exercise intensity is a significant variable and structured high-intensity interval training (HIIT) has been demonstrated to improve both whole-body and skeletal muscle metabolic health in different populations. Conversely, fatigue accumulation, if not resolved, leads to overwork, chronic fatigue syndrome (CFS), overtraining syndrome up to alterations of endocrine function, immune, systemic inflammation, and organic diseases with health threat. In response to temporary increases in stress during training, some athletes are unable to maintain sufficient caloric intake, thus suffering a negative energy balance that causes further stress. The regulation of the energy balance is controlled by the central nervous system through an elaborate interaction of the signalling that involves different tissues such as leptin, adiponectin and ghrelin whose provide important feedback to the hypothalamus to regulate the energy balance. Although exercise-induced reactive oxygen species are required for normal force production in muscle, high levels of ROS appear to promote contractile dysfunction. However, a high level of oxidative stress in may induce a rise in inflammatory markers and a disregulation in expression of adiponectin, leptin and grelin.

Detection of Functional Overreaching in Endurance Athletes Using Proteomics

No reliable biomarkers exist to identify athletes in various training states including functional overreaching (FOR), non-functional overreaching (NFOR), and overtraining syndrome (OTS). Participants (N = 10, age 38.3 ± 3.4 years) served as their own controls and in random, counterbalanced order either ran/cycled 2.5 h (70.0 ± 3.7% VO_2max) three days in a row (FOR) or sat in the lab (rest) (separated by three weeks; 7:00–9:30 am, overnight fasted state). Participants provided fingerprick samples for dried blood spot samples (DBS) pre- and post-exercise/rest, and then during two recovery days. DBS proteins were measured with nanoLC-MS in data-independent acquisition (DIA) mode, and 593 proteins were identified and quantified. Proteins were considered for the FOR cluster if they were elevated during one of the two recovery days but not more than one of the exercise days (compared to rest). The generalized estimating equation (GEE) was used to identify proteins linked to FOR. A total of 13 proteins was linked to FOR and most were associated with the acute phase response and innate immune system activation. This study used a system-wide proteomics approach to define a targeted panel of blood proteins related to FOR that could form the basis of future NFOR- and OTS-based studies.

Physical fitness, hormonal, and immunological responses during prolonged military field training

Physical fitness is crucial to warfighters' performance in the battlefield. Previous studies have shown negative changes in their hormonal and neuromuscular responses induced by military field training (MFT). The purpose of this study was to investigate the changes in hormonal and immunological values and body composition during a prolonged MFT and to find out how warfighters' physical condition influences these changes. Conscripts (n = 49, age 20 ± 1 years, height 179 ± 9 cm, body mass 73.8 ± 7.8 kg, fat 12.6 ± 3.7% and BMI 23 kg/m²) were measured before, during, after MFT, and after a 4-day recovery period. Serum insulin-like growth factor-1 (IGF-1), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) concentrations, creatine kinase (CK) activity and leptin concentration were analyzed as well as body composition throughout MFT. Neuromuscular performance was assessed via lower and upper body muscle endurance at the beginning of the study. During MFT, there was a significant decrease (P < 0.05) in body mass (2.3%), fat mass (7.7%) and in muscle mass (2.2%), but all of these values recovered to PRE-levels after the recovery period. Serum IGF-1 (22%) and leptin decreased (66%) while CK increased (88%) significantly (P < 0.05) during MFT but recovered at the end of MFT. Upper body dynamic and trunk isometric muscular endurance had a positive correlation (r = 0.37. P < 0.05) with the change in IGF-1 during MFT and a negative correlation with the changes in CK (-0.34, P < 0.05). The results show that there were negative changes in conscript's body composition and hormonal and immunological values during the prolonged MFT. These changes suggest that the physiological stress was high during MFT. High levels of upper body and trunk muscular strength were negatively correlated with warfighters' physiological effects and should therefore be developed prior to actual deployment to reduce the physical decline experienced during prolonged MFTs.

Variations in leptin, nesfatin-1 and irisin levels induced by aerobic exercise in young trained and untrained male subjects

The aims of this study were to investigate the impacts of acute aerobic exercise on circulating levels of hormones associated with energy metabolism, namely leptin, nesfatin-1 and irisin, in trained and untrained male subjects and to determine whether the timing of the exercise (i.e. morning or night) amplified these impacts. Thirty trained (19.2±0.7 years) and 30 untrained (19.5±0.6 years) male subjects performed two aerobic running exercises (3 days between tests) to 64-76% of the subjects' maximal heart rate for about 30 min. Pre- and post-exercise venous blood samples were taken and analysed for leptin, nesfatin-1 and irisin using enzyme-linked immunosorbent assay (ELISA). Paired samples and independent samples t-tests were used to analyse data. Irisin levels increased in all the subjects (p<0.001). In both groups, nesfatin-1 levels increased significantly after the night-time exercise (p<0.05). Importantly, leptin and nesfatin-1 levels varied among the trained and untrained groups: Both leptin and nesfatin-1 levels increased in 4 (13%) and 12 (40%) subjects, respectively, after the morning exercises, and they increased in 9 (30%) and 10 (33%) subjects, respectively, after the night-time exercise. They decreased in 5 (16%) and 7 (23%) subjects, respectively, after the morning exercise and in 6 (20%) and 3 (10%) subjects, respectively, after the night-time exercise. Exercise may result in increased energy consumption by altering irisin levels. However, due to variations among individuals, increasing leptin and nesfatin-1 levels by reducing food intake may not be applicable.

New approaches to determine fatigue in elite athletes during intensified training: Resting metabolic rate and pacing profile

Background

Elite rowers complete a high volume of training across a number of modalities to prepare for competition, including periods of intensified load, which may lead to fatigue and short-term performance decrements. As yet, the influence of substantial fatigue on resting metabolic rate (RMR) and exercise regulation (pacing), and their subsequent utility as monitoring parameters, has not been explicitly investigated in elite endurance athletes.

Method

Ten National-level rowers completed a four-week period of intensified training. RMR, body composition and energy intake were assessed PRE and POST the four-week period using indirect calorimetry, Dual-Energy X-Ray Densitometry (DXA), and three-day food diary, respectively. On-water rowing performance and pacing strategy was evaluated from 5 km time trials. Wellness was assessed weekly using the Multicomponent Training Distress Scale (MTDS).

Results

Significant decreases in absolute (mean ± SD of difference, p-value: -466 ± 488 kJ.day^-1, p = 0.01) and relative RMR (-8.0 ± 8.1 kJ.kg.FFM^-1, p = 0.01) were observed. Significant reductions in body mass (-1.6 ± 1.3 kg, p = 0.003) and fat mass (-2.2 ± 1.2 kg, p = 0.0001) were detected, while energy intake was unchanged. On-water 5 km rowing performance worsened (p < 0.05) and an altered pacing strategy was evident. Fatigue and total mood disturbance significantly increased across the cycle (p < 0.05), and trends were observed for reduced vigour and increased sleep disturbance (p < 0.1).

Conclusion

Four weeks of heavy training decreased RMR and body composition variables in elite rowers and induced substantial fatigue, likely related to an imbalance between energy intake and output. This study demonstrates that highly experienced athletes do not necessarily select the correct energy intake during periods of intensified training, and this can be assessed by reductions in RMR and body composition. The shortfall in energy availability likely affected recovery from training and altered 5 km time trial pacing strategy, resulting in reduced performance.

Changes in inflammatory markers in estonian pubertal boys with different BMI values and increments: A 3-Year Follow-Up Study

OBJECTIVE

Serum inflammatory markers could help to identify those boys with overweight (OWB) who gain weight more extensively during puberty. This study aimed to examine the longitudinal changes in different serum inflammatory markers through puberty in boys with different BMI values and increments.

METHODS

Twenty-six OWB and 29 normal-weight boys (NWB) were followed yearly for 3 years to measure changes in BMI and serum concentrations of 12 inflammatory markers.

RESULTS

OWB had higher (P < 0.033) baseline interleukin (IL)-6, IL-8, interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and IL-1α concentrations in comparison with NWB. Over the 3-year period, IFN-γ (P = 0.0001) and TNF-α (P = 0.0042) decreased more in OWB compared to NWB. Serum IL-8, monocyte chemoattractant protein (MCP)-1, and leptin increased further in those OWB who gained BMI more extensively through puberty compared to OWB who gained weight at slower rates (P < 0.033).

CONCLUSIONS

Serum IFN-γ and TNF-α levels decreased more during pubertal years in OWB compared to NWB, indicating that pubertal maturation itself may have a favorable impact on the inflammation of obesity. Serum IL-8, MCP-1, and leptin could help to identify OWB who gain BMI more extensively during pubertal years.

Changes in cytokines, leptin, and IGF-1 levels in overtrained athletes during a prolonged recovery phase: A case-control study

We investigated how cytokines are implicated with overtraining syndrome (OTS) in athletes during a prolonged period of recovery. Plasma IL-6, IL-10, TNF-α, IL-1β, adipokine leptin, and insulin like growth factor-1 (IGF-1) concentrations were measured in overtrained (OA: 5 men, 2 women) and healthy control athletes (CA: 5 men, 5 women) before and after exercise to volitional exhaustion. Measurements were conducted at baseline and after 6 and 12 months. Inflammatory cytokines did not differ between groups at rest. However, resting leptin concentration was lower in OA than CA at every measurement (P < 0.050) but was not affected by acute exercise. Although IL-6 and TNF-α concentrations increased with exercise in both groups (P < 0.050), pro-inflammatory IL-1β concentration increased only in OA (P < 0.050) and anti-inflammatory IL-10 was greater in CA (P < 0.001). In OA, exercise-related IL-6 and TNF-α induction was enhanced during the follow-up (P < 0.050). IGF-1 decreased with exercise in OA (P < 0.050); however, no differences in resting IGF-1 were observed. In conclusion, low leptin level at rest and a pro-inflammatory cytokine response to acute exercise may reflect a chronic maladaptation state in overtrained athletes. In contrast, the accentuation of IL-6 and TNF-α responses to acute exercise seemed to associate with the progression of recovery from overtraining.

Longitudinal associations between bone and adipose tissue biochemical markers with bone mineralization in boys during puberty

Background

We investigated longitudinal relationships between the biochemical markers of bone and adipose tissue with bone mineral content (BMC), bone mineral density (BMD), moderate-to-vigorous physical activity (MVPA) and sedentary time (SED) in pubertal boys.

Methods

Ninety-six boys (11.9 ± 0.6 years old) were measured at baseline, after 12 and 24 months. Body composition (fat mass [FM], lean body mass [LBM]), and whole body (WB), lumbar spine (LS) and femoral neck (FN) BMD and BMC were assessed. Additionally, serum leptin, adiponectin, osteocalcin (OC) and C-terminal telopeptide of type I collagen (CTX) were measured.

Results

OC had a strong longitudinal inverse effect on changes in WB_BMD (p < 0.001) and LS_BMD (p = 0.021), while CTX had an inverse effect only on changes in FN_BMD (p = 0.011). Leptin had an inverse effect on changes in WB_BMC/WB_BMD (p = 0.001), FN_BMD (p = 0.002) and LS_BMD (p = 0.001). MVPA showed a longitudinal inverse effect on changes in leptin (p = 0.030), however no longitudinal effect of SED to biochemical markers of bone and adipose tissue was found.

Conclusions

Bone metabolism markers have negative effect on bone mineral accrual during puberty. Increases in MVPA affect leptin, suggesting a positive link of MVPA through leptin metabolism on increases in bone mineralization during puberty.

Adipocytokines and bone metabolism markers in relation to bone mineral values in early pubertal boys with different physical activity

BACKGROUND

We aimed to examine the associations of adipocytokines and circulating bone metabolism markers with bone mineral parameters in early pubertal boys with different physical activity level.

METHODS

Eighty-six early pubertal boys were divided into active and non-active boys according to the accumulated moderate-to-vigorous physical activity (MVPA) level. Body composition and bone mineral parameters were assessed and testosterone, leptin, adiponectin, osteocalcin (OC), and C-terminal telopeptide of type I collagen (CTX) were measured.

RESULTS

Active subjects had significantly lower (p<0.05) body mass, body mass index (BMI), fat mass (FM), leptin, and sedentary time values, while non-active subjects had lower (p<0.05) vigorous physical activity level and femoral neck bone mineral density (FN-BMD). OC contributed to the models in physically active group and explained 6.6% and 9.7% of variance in whole body (WB) [F(5,44)=10.847; p<0.001] and lumbar spine bone mineral content (LS-BMC) [F(5,44)=4.158; p=0.004], respectively. No other biochemical parameters were found to be related to bone mineral parameters in either the active or non-active group.

CONCLUSIONS

Bone metabolism markers were positively correlated with bone mineral values only in active pubertal boys. Leptin and adiponectin were not related to bone mineral parameters in active and non-active pubertal boys.

Adipocytokine and ghrelin levels in relation to bone mineral density in prepubertal rhythmic gymnasts entering puberty: a 3-year follow-up study

PURPOSE

To investigate changes in bone mineral density (BMD) in rhythmic gymnasts (RG) entering puberty and their age-matched untrained controls (UC) over the 36-month period, and associations with leptin, adiponectin and ghrelin over this period.

METHODS

Whole body (WB), lumbar spine (LS) and femoral neck (FN) BMD, WB bone mineral content (BMC), and leptin, adiponectin and ghrelin were measured in 35 RG and 33 UC girls at baseline and at 12-month intervals over the next 3 years. The change over the 36 months was calculated (∆ score).

RESULTS

The pubertal development over the next 36 months was slower in RG compard to UC, while there was no difference in bone age development between the groups. BMD at all sites was higher in RG in comparison with UC at every measurement point. ∆LS BMD and ∆FN BMD, but not ∆WB BMD and ∆WB BMC, were higher in RG compared with UC. None of the measured hormones at baseline or their ∆ scores correlated with ∆BMD and ∆BMC in RG. Baseline fat free mass correlated with ∆WB BMD and ∆WB BMC in RG, while baseline leptin was related to ∆WB BMC, ∆WB BMD and ∆LS BMD in UC.

CONCLUSIONS

Measured baseline hormones and their ∆ scores did not correlate with increases in bone mineral values in RG entering puberty. Although the pubertal development in RG was slower than in UC, high-intensity training appeared to increase BMD growth and counterbalance negative effects of slow pubertal develpment, lower fat mass and leptin in RG.

Can clinicians and scientists explain and prevent unexplained underperformance syndrome in elite athletes: an interdisciplinary perspective and 2016 update

The coach and interdisciplinary sports science and medicine team strive to continually progress the athlete's performance year on year. In structuring training programmes, coaches and scientists plan distinct periods of progressive overload coupled with recovery for anticipated performances to be delivered on fixed dates of competition in the calendar year. Peaking at major championships is a challenge, and training capacity highly individualised, with fine margins between the training dose necessary for adaptation and that which elicits maladaptation at the elite level. As such, optimising adaptation is key to effective preparation. Notably, however, many factors (eg, health, nutrition, sleep, training experience, psychosocial factors) play an essential part in moderating the processes of adaptation to exercise and environmental stressors, for example, heat, altitude; processes which can often fail or be limited. In the UK, the term unexplained underperformance syndrome (UUPS) has been adopted, in contrast to the more commonly referenced term overtraining syndrome, to describe a significant episode of underperformance with persistent fatigue, that is, maladaptation. This construct, UUPS, reflects the complexity of the syndrome, the multifactorial aetiology, and that ‘overtraining’ or an imbalance between training load and recovery may not be the primary cause for underperformance. UUPS draws on the distinction that a decline in performance represents the universal feature. In our review, we provide a practitioner-focused perspective, proposing that causative factors can be identified and UUPS explained, through an interdisciplinary approach (ie, medicine, nutrition, physiology, psychology) to sports science and medicine delivery, monitoring, and data interpretation and analysis.

Body composition, maximal aerobic performance and inflammatory biomarkers in endurance-trained athletes

This study was designed to examine the relationships between body composition, cardiorespiratory fitness and simultaneously measured inflammatory parameters in endurance-trained athletes. In 20 well-trained rowers (19·0 ± 2·9 years; 185·6 ± 4·8 cm; 85·7 ± 10·8 kg; 17·1 ± 5·1% body fat; maximal oxygen consumption [VO₂ max]: 63·9 ± 8·5 ml min^-1  kg^-1 ), body composition was measured by dual-energy X-ray absorptiometry and cardiorespiratory fitness by direct VO₂ max test. Twelve inflammatory factors [interleukin (IL)-2, IL-4, IL-6, IL-8, IL-10, vascular endothelial growth factor, interferon-gamma (IFN-γ), tumour necrosis factor-alpha, IL-1α, IL-1β, monocyte chemoattractant protein-1 (MCP-1), epidermal growth factor (EGF)] were analysed from serum samples. Serum IFN-γ was related (P<0·05) to fat-free mass (FFM) (r = -0·56) and muscle mass (r = -0·50). The stepwise regression analysis showed that IFN-γ explained 27·5%, and IFN-γ and IL-6 together explained 39·8% of the variability of FFM, while IFN-γ explained 21·1%, and IFN-γ together with EGF explained 36·6% of the variability of muscle mass in male rowers. Serum IL-8 (r = -0·65) and VEGF (r = -0·48) correlated (P<0·05) with VO₂ max kg^-1 . Serum IL-8 explained 38·5% of the variability of VO₂ max kg^-1 . Significant correlations were also found among several inflammatory parameters, indicating that various inflammatory cytokines act on the body as an ensemble. In conclusion, this cross-sectional study in endurance-trained male rowers showed that FFM and muscle mass were negatively correlated with serum IFN-γ level, whereas cardiorespiratory fitness was negatively related to serum IL-8 level.

Chronic physical stress differences between genders in a military training on the Amazon jungle

This study aimed to investigate the gender difference in the manifestation of physical stress in a strenuous military training on Amazon jungle, using alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK) and lactate dehydrogenase (LDH) markers, measured before and after an adaptation to jungle training. The sample consisted of 49 military volunteers, 35 male and 14 female, recently moved to the Amazon region. All plasma levels rose after the training. Serum ALT (male and female) and AST (male and female), although borderline, remained within normal limits. Already plasma levels of CK (both male and female) and LDH (male and female) largely exceeded the normal range. The average of all markers listed in female gender remained below the levels of the male gender. However, significant differences in biomarkers ALT, AST and CK between genders were found. The study points out that, in a jungle environment, biometric markers ALT, AST, CK and LDH are efficient for monitoring chronic physical stress in both genders, when used in combination. The influence of the weather on the occurrence of physical stress in unacclimated people of both genders, and the lower responses in the levels of ALT, AST, LDH and CK in females were discussed basing on the scientific literature.