Burnout is a growing problem in high-performance sport and has negative consequences for athletes (e.g., mental ill-health). It is therefore important to effectively monitor athlete burnout to aid intervention efforts. While self-report measures are available (e.g., athlete burnout questionnaire), the limitations associated with these measures (e.g., social desirability bias) means that objective physiological markers may also be useful. Thus, this article critically discusses potential biomarkers of athlete burnout, drawing on research inside and outside of sport to offer an overview of the current state-of-the-art in this research area. First, it outlines what athlete burnout is, its deleterious consequences, and discusses existing psychological assessments. The article then critically discusses literature on hypothalamic-pituitary-adrenal axis (e.g., salivary cortisol) and autonomic nervous system (e.g., heart rate variability) indices of burnout, highlighting some promising biomarkers for future research (e.g., salivary cortisol at bedtime, vagally-mediated heart rate variability at rest). Finally, the article concludes by highlighting key considerations and offering recommendations for future research (e.g., use of more homogenous methods in assessing burnout and physiological parameters). As a result, the intention of this article is to spark more higher quality research on the psychophysiology of athlete burnout, thereby helping tackle this prominent issue in high-performance sport.

During an IRONMAN, the pacing strategy in the running segment differs significantly between sexes. However, it is unknown if sex affects the running pace in shorter triathlon events. This study compared the pacing strategy between sexes during a 5-km running test performed following a 20-km cycle (sprint triathlon distances). Participants included 16 men (34.7±7.5 years) and 16 women (39.5±7.7 years). A cardiopulmonary exercise test to measure maximal oxygen uptake (˙VOmax) and a functional threshold power (FTP) were performed. Body composition was measured using a dual-emission X-ray absorptiometry system. Participants cycled at 90% FTP for 20 km and ran as fast as possible for 5 km. The total time spent cycling 20 km was shorter (~11%) in male than in female athletes (p<0.001). Similarly, the time spent to run 5 km was shorter in male (~11%) than in female athletes (p=0.006). Male athletes performed the last 600 m of the 5km race significantly faster than the initial meters (p<0.05). Female athletes performed the 5-km race without pace variation (p>0.05). In conclusion, apart from the sex differences associated with performance in short-term triathlon events, the pacing strategy was also different.

This study clarified whether instrument-assisted soft tissue mobilization (IASTM) on the plantar surface changes abductor hallucis and plantar fascia stiffness at rest and medial longitudinal arch height under low- and high-loading conditions. IASTM was performed to one foot of the twenty-eight young men (IASTM condition), and the other foot of them was assigned to the control condition. Using ultrasonography, the resting shear wave propagation velocity of the abductor hallucis and plantar fascia and navicular height in a seated posture were determined. The foot contact area during quiet standing was measured using a foot-scan system. The shear wave propagation velocity of the plantar fascia significantly decreased by 10.8% in the IASTM condition but did not change significantly in the control condition. The magnitude of change in the shear wave propagation velocity of the plantar fascia was negatively correlated (r=- 0.660) with the shear wave propagation velocity of the plantar fascia before IASTM. The interaction of time and condition was not significant for the shear wave propagation velocity of the abductor hallucis, navicular height, or foot contact area. The current study revealed that IASTM on the plantar surface affected tissue stiffness but did not change the structure of the foot.

The aim of the present study was to examine: 1) the coexistence of excessive body weight and low cardiorespiratory fitness (CRF), at a level to be considered unhealthy, and 2) the stability (tracking) of this profile. 1754 European boys, aged 8- to 14-years old, were tested for CRF and based on international cut points were classified as having healthy (H) or unhealthy (UN) CRF. Based on BMI they were classified as having normal weight (N), or overweight or obesity (OO). Chi-square was performed with four groups (i.e. N/H, N/UN, OO/H and OO/UN) and the odds ratios were calculated (cross-sectional analysis). A sub-group of 353 boys were followed for an average of 3.79±0.83 years (range: 2.97-6.06; longitudinal analysis). The odds that a boy was with OO/UN profile compared to the normal body weight category ranged from 2.67 (13-years old) to 6.74 (9-years old). 56.6% of the participants remained in the same category, whereas 28.0% of them had ≥1 change in category to worst in the second assessment (Cohen Kappa= 0.557, p<0.001; substantial agreement). The odds ratios of having boys with unhealthy profile of combined excessive body weight and low CRF ranged from medium to large. The stability of unhealthy profile was substantial.

This study examines the energy expenditure and physiological responses associated with short-term quadrupedal locomotion compared to bipedal walking in humans. It aims to support evolutionary theory and explore quadrupedal locomotion's potential for enhancing fitness and health. In a randomized crossover design, twelve participants performed quadrupedal and bipedal walking on a treadmill at identical speeds. Physiological responses, including energy expenditure, carbohydrate oxidation rates, respiratory rate, and heart rate, were measured during both forms. Quadrupedal walking significantly increased total energy expenditure by 4.15 Kcal/min [95% CI, 3.11 - 5.19 Kcal/min], due to a rise in carbohydrate oxidation of 1.70 g/min [95% CI, 1.02 - 2.24 g/min]. It also increased respiratory and heart rates, indicating higher metabolic demands. The exercise mainly activated upper limb muscles and the gluteus maximus in the lower limbs. Ten minutes of quadrupedal walking at the same speed as bipedal walking resulted in a 254.48% increase in energy consumption. This simple form of locomotion offers a strategy for enhancing physical activity and supports the idea that energy optimization influenced the evolution of efficient bipedal locomotion.

The aim of this study was to investigate the effect of 8 weeks of hypoxic exposition and physical training on healthy mice femur outcomes analyzed through conventional statistic and complex networks. The mice were divided into four groups, subjected to physical training (T; 40 min per day at 80% of critical velocity intensity) or not (N), exposed to hypoxic environment ("Living High-Training Low" model - LHTL; 18 h per day, FIO=19.5%; Hyp) or not (Nor). The complex network analysis performed interactions among parameters using values of critical "r" of 0.5 by Pearson correlations to edges construction, with Fruchterman-Reingold layout adopted for graph visualization. Pondered Degree, Betweenness, and Eigenvector metrics were chosen as centrality metrics. Two-way ANOVA, t-test and Pearson correlation were used with P<0.05. Femur phosphorus of T-Hyp was higher than all other groups (P<0.05) and correlated with bone density (r=0.65; P=0.042), bone mineral density (r=0.67; P=0.034) and% of mineral material (r=0.66, P=0.038). Overall, the complex network demonstrated improvements in bone volume, % of mineral material, bone density, and bone mineral density for T-Hyp over other groups. Association of physical training and hypoxia improved bone quality for healthy mice.

Kinematics and release parameters are important factors of throw location, yet an understanding of their relationship has yet to be achieved. This study sought to explore this relationship. Kinematic data were collected for seventy-seven collegiate pitchers. Fifty-seven kinematic parameters were included in path analyses for horizontal (HPL) and vertical plate locations (VPL). Release angles were set as mediating variables (MED) between independent (IV) and dependent (DV) variables. Eleven kinematic variables directly (13 indirectly) affected VPL, while 23 directly affected HPL (10 indirectly). Linear mixed models revealed that lateral trunk flexion at ball release (BR) (R2=.908, BIC=-598, ICC=.528) best explained VPL. Trunk flexion at foot contact (FC) (R2=.944, BIC=-607, ICC=.776), mediolateral centre of mass (COM) displacement at FC (R2=.974, BIC=-573, ICC=.918), and BR (R2=.967, BIC=-593, ICC=.865), and pelvis rotation at BR (R2=.965, BIC=-588, ICC=.895) models were identified for HPL. Results indicate the relationship between pitching kinematics, release conditions, and throw location is complex. Biomechanics can influence release parameters, which in turn impacts throw location. This work may serve to understand better how biomechanics influence performance.

Pneumatic resistance training (PRT) facilitates a longer time under tension that might lead to greater changes in body composition when compared to traditional resistance training (TRT), possibly enhancing serum metabolite concentrations indicative of healthy metabolic function. To assess the impact of PRT and TRT on muscular strength, body composition, and serum metabolome, 69 men (age: 31.8±7.2 years, height: 179.7±5.4 cm, weight: 81.1±9.9 kg) were randomized into two 10-week intervention groups (PRT:n=24 and TRT:n=24) and one control group (CON:n=21). Serum metabolite concentrations were assessed before and after the training intervention by high-throughput nuclear magnetic resonance. Fat mass and lean mass were obtained by bioimpedance analysis. The training intervention resulted in an increase in lean mass for both PRT (1.85±2.69%; p=0.003) and TRT (2.72±4.53%; p=0.004), while only PRT reduced statistically significantly in body fat percentage (PRT: -5.08±10.76%; p=0.019). Only in PRT and TRT significant increases in small high-density lipoproteins (S-HDL-L) and small HDL particles (S-HDL-P) were observed. When controlling for fat and lean mass, the effects on S-HDL-L/S-HDL-P diminished. Network analysis may suggest that PRT and TRT result in an increase in network connectivity and robustness. It appears that the observed improvements are associated with changes in body composition.

The study aimed to determine the acute effects of subtetanic neuromuscular electrical stimulation (NMES) combined with active recovery between sprint exercises on blood lactate accumulation, sprint performance, and muscle fatigue. Sixteen healthy young individuals [23(4) years, 10 males] underwent a 1-min rest followed by sprint interval training consisting of four 15-sec maximal sprint exercises with three 5-min active cycling sessions. Participants engaged in voluntary cycling at 40% of peak oxygen consumption, with or without NMES (VOLES or VOL; interventions). Blood lactate concentration ([La]) was assessed at the end of the rest and each intervention periods. Mean power was assessed during each sprint exercise session. Maximum voluntary contraction (MVC) of the knee extensor was measured before and after sprint interval training to evaluate muscle fatigue. The [La] was significantly higher in VOLES than in VOL (main effect, P=0.037). Mean power did not differ between conditions (main effect and interaction, P>0.050). MVC after sprint interval exercise was significantly lower in VOLES than in VOL (interaction, P<0.001). Subtetanic NMES combined with voluntary cycling enhanced blood lactate accumulation and induced greater voluntary fatigue but resulted in similar peripheral muscle fatigue and sprint exercise performance compared with voluntary cycling without NMES.

This systematic review and meta-analysis aimed to identify the association between genetic polymorphisms and tendon and ligament injuries in adolescent and adult athletes of multiple competition sports. The PubMed, Web of Science, EBSCO, Cochrane Library, and MEDLINE databases were searched until July 7, 2023. Eligible articles included genetic studies on tendon and ligament injuries and comparisons between injured and non-injured athletes. This review included 31 articles, comprising 1,687 injury cases and 2,227 controls, from a meta-analysis of 12 articles. We identified 144 candidate gene polymorphisms (only single nucleotide polymorphisms were identified). The meta-analyses included vascular endothelial growth factor A (VEGFA) rs699947, collagen type I alpha 1 rs1800012, collagen type V alpha 1 rs12722, and matrix metalloproteinase 3 rs679620. The VEGFA rs699947 polymorphism showed a lower risk of injuries in athletes with the C allele ([C vs. A]: OR=0.80, 95% CI: 0.65-0.98, 3.82%, =0.03). The risk of these injuries were not affected by other polymorphisms. In conclusion, the VEGFA rs699947 polymorphism is associated with the risk of tendon and ligament injuries in athletes. This study provides insights into genetic variations that contribute to our understanding of the risk factors for such injuries in athletes.

The objective of the study was to assess chronotype, sleep hygiene, and sleep characteristics of Italian athletes in order to identify differences among sport disciplines (team- vs individual-sports), level of competition (Elite vs Non-Elite) and sexes. Moreover, correlations between chronotype, sleep hygiene and sleep quality were evaluated. Two hundred eighty Italian athletes (Females:113; Males:167) participated in the study. They completed the Pittsburgh Sleep Quality Index (PSQI), the Sleep Hygiene Index (SHI) and the MorningnessEveningness Questionnaire (MEQ). Among the athletes, 66.4% were intermediate-type, 21.8% were morning-type and 11.8% were evening-type. 55.4% of the sample was classified as good sleeper (PSQI<5), while 16.1% had poor sleep hygiene (SHI≥35). Females had higher total sleep time (p=0.022) than males. Individual-sports showed more morning-oriented score (p=0.001) and lower PSQI (p=0.006) and SHI (p<0.001) scores, with earlier timing of sleep (bedtime:p<0.001; wake-up time:p<0.001) compared to teamsports. Elite athletes exhibited greater sleep efficiency (p=0.009), and lower sleep latency (p=0.018) and wake after sleep onset (p=0.043) than Non-Elite athletes. Additionally, significant correlations were found between PSQI and SHI (r=0.43, p<0.001), and between MEQ and SHI (r=-0.35, p<0.001). This study yields crucial insights into the sleep behaviors of Italian athletes, revealing that nearly half of the sample were bad sleepers.

High-intensity interval training (HIIT) has been suggested as an effective treatment approach of childhood obesity. The objective of the present study was to examine intensity, enjoyment, and perceived exertion of a 4x4-minute play-based HIIT program for children and adolescents with obesity. 83 participants (42.2% girls, 12.3±1.5 years, 57.8% boys, 12.0±1.6 years) completed a 12-week intervention comprising three weekly sessions. After nine sessions (weeks 2, 6, and 11), participants rated perceived exertion (RPE) with a Borg scale and enjoyment of activities using the Physical Activity Enjoyment Scale (PACES). Heart rate (HR) was recorded to assess time spent in high- and moderate-intensity. Participants spent more time in high-intensity during strength-based(P=0.004) and running-based(P=0.007) activities compared to ball games, and more time was spent in moderate-intensity during ball games compared to strength-based(P=0.033) and running-based(P=0.028) activities. Overall, boys spent more time in moderate-intensity than girls(P=0.007). Participants rated RPE lower for ball games than for strength-based(P<0.001) and running-based(P<0.001) activities. Boys rated running-based activities more enjoyable than girls(P=0.021). Exercise intensity and RPE vary by activity in HIIT for children and adolescents with obesity. Ball games led to less high-intensity time and were seen as less exhausting. No differences in RPE or enjoyment were found over time.

This study aimed to analyze the associations between recovery of low-frequency fatigue, jump height and perceptual responses following official soccer matches. Forty-two male youth elite soccer players (age: 17.13±0.70 years; height: 179.17±5.94 cm; weight: 69.74±4.91 kg) participated in this study. Low-frequency fatigue, countermovement jump, perceived fatigue, muscle soreness and perceived recovery were assessed at -2h, +30 min, +24h and +48h relative to the match. Linear mixed models analysis showed that low-frequency fatigue was reduced at the match-end (ES=-0.679 [95% CI = -1.01; -0.34]; p<.001) but returned to baseline after 24h (ES=0.149 [95% CI = -0.26; 0.56]; p=1.00). Perceptual responses were impaired for up to 48 hours following the match (ES=-0.868-1.174; p<.001). Countermovement jump did not differ between any time point (ES=-0.204-0.216; p>0.05). Additionally, the within-subject correlation analysis showed that low-frequency fatigue pre- to post-match changes presented moderate to large associations with perceived fatigue (rm[57]=-0.43; p<.001), muscle soreness (rm[57]=-0.52; p<.001) and perceived recovery (rm[57]=0.38; p=.003). The assessment of low-frequency fatigue could serve as an additional objective measurement for monitoring post-match fatigue, as findings suggest that young elite soccer players experience transient reductions following match-play, which are strongly correlated with subjective markers of recovery.

To explore the genetic architecture underlying exercise-induced fat mass change, we performed a genome-wide association study with a Chinese cohort consisting of 442 physically inactive healthy adults in response to a 12-week exercise training (High-intensity Interval Training or Resistance Training). The inter-individual response showed an exercise-induced fat mass change and ten novel lead SNPs were associated with the response on the level of P<1×10. Four of them (rs7187742, rs1467243, rs28629770 and rs10848501) showed a consistent effect direction in the European ancestry. The Polygenic Predictor Score (PPS) derived from ten lead SNPs, sex, baseline body mass and exercise protocols explained 40.3% of the variance in fat mass response, meanwhile importantly the PPS had the greatest contribution. Of note, the subjects whose PPS was lower than -9.301 had the highest response in exercise-induced fat loss. Finally, we highlight a series of pathways and biological processes regarding the fat mass response to exercise, e.g. apelin signaling pathway, insulin secretion pathway and fat cell differentiation biological process.

This study investigated the ventilatory thresholds (VT1 and VT2) along with the corresponding heart rates, velocities and % of V̇O max at which these thresholds are reached in professional female soccer players. It also examined positional differences in the aforementioned parameters. Thirty-three professional players from two teams (age range 18-31 years) were recruited. The players underwent maximal exercise testing on the treadmill for the detection of VT1 (V̇E versus V̇O plot) and VT2 (V̇E versus V̇CO plot). The test began at a speed of 6km/h and was increased by 2 km/h every 3.15 minutes, with the inclination constant at 1%. Results indicated that the players had an average V̇O max of 50.24 ml·kg.min. VT1 (% max) and VT2 (% max) were shown at 72.87% and 91.26% of V̇O max, respectively. The respective velocities at VT1 and VT2 were indicated at 10.85 km/h and 12.91 km/h, respectively, while the average VV̇O max was 14.61 km/h. The average heart rates at VT1, VT2 and V̇O max were 159.33, 185.15 and 192.85 beats per minute, respectively. Furthermore, analysis of variance ANOVA indicated significant differences in velocity at V̇Omax. This study provides important normative data regarding the ventilatory thresholds of female soccer players.

This study aimed to evaluate the applicability of the 10-minute submaximal treadmill test (T10 test), a self-paced test, in determining critical speed (CS) and predicting running performance. Specifically, we sought to identify the percentage of T10 velocity (vT10) that runners performed in official distance races, and to compare physiological and performance indicators between sexes. 60 recreational runners (n=34 males and n=26 females) underwent a maximum incremental test, the novel T10 test, and ran 1200-m and 2400-m on the track. Runners self-reported their best performance times. Generalized Linear Model was used to compare running performances between sexes. For both males and females, the %vT10 in 5 km, 10 km, and half-marathon races occurred at 107.5% and 106.5%, 99.9% and 100.8%, and 92.6% and 97.1%, respectively. There was no interaction effect (p=0.520) and no main effect of sex (p=0.443). There was a main effect of distance (p<0.001), indicating that %vT10 in the 5km race differed from that found in the 10 km race (p=0.012), as well as in the half-marathon (p<0.001). Our findings suggest that %vT10 values can be used to determine pace in recreational endurance runners for race distances regardless of sex.

This study assessed the repeated sprint performance in relation to circadian rhythm during different menstrual cycle phases (MCP). Twelve volunteer eumenorrheic women team sport athletes performed 5×6-s cycling sprints in morning (9 am to 10 am) and evening (6 pm to 7 pm) sessions during the mid-follicular (FP, 6-10 d) and luteal phases (LP, 19-24 d). Body weight, oral body temperature, resting heart rate and lactate levels together with estradiol, progesterone and cortisol levels were determined before tests. Relative peak and mean power and performance decrements were determined as performance variables and maximum heart rate, lactate and ratings of perceived exertion were determined as physiological variables. Evening body temperatures were significantly higher. Cortisol levels were higher in the morning and in the FP. Resting lactate levels did not vary with MCP or time of day, but a significant MCP x time of day interaction was observed. Body weight showed no change according to time of day and MCP. There was no significant effect of MCP and time of day on performance and physiological variables, in contrast, maximum lactate values were notably higher in the evening. In conclusion, MCP and time of day need not be considered during repeated sprint exercises of eumenorrheic women athletes.

Large cohort studies have reported that former professional football players have an increased risk of mortality from neurodegenerative disease. Due to emerging concerns regarding the safety of heading the technique is now banned for players under 12. The aim of this systematic review was to evaluate the association between heading exposure and cognitive function in professional football players. A search strategy was devised and entered into seven electronic databases: MEDLINE, Embase, Web of Science, PsycINFO, CENTRAL, SportDiscus and PEDro. The search identified 563 records. After screening records and applying the eligibility criteria, nine cross-sectional studies (n = 925) were included in the review, investigating 452 current and 473 former players (859 males, 66 females). Six studies (n = 595) reported evidence for an association between heading and impaired cognitive function, while three studies (n = 330) reported no association. Diverse cognitive domains were investigated, which might underline the disparity in these results. The association between heading and cognitive function in professional football appears likely but remains inconclusive. Methodological heterogeneity and variability in the presentation of results limits the conclusions drawn. Prospective longitudinal studies using standardised methods, and including females, are required to provide evidence to support or refute an association.

Iron and vitamin D deficiencies can affect athletes' health and performance. However, the epidemiology and associated risk factors remain unclear. Forty-three elite female athletics athletes (20.2 ± 1.9 years) were included. A survey regarding the training schedule and Eating Attitudes Test-26, body composition, bone mineral density, and serum 25-hydroxyvitamin D (25(OH)D) and ferritin levels were assessed. Mean serum 25(OH)D and ferritin levels were 25.2 ± 5.5 ng/mL and 29.0 ± 13.2 ng/mL, respectively, and 83.7% and 41.9 % of athletes had vitamin D and ferritin insufficiency, respectively. Serum 25(OH)D level was negatively correlated with the number of rest days per week (Coefficient, -6.19; 95% confidence interval [CI], -9.82--2.57; p = 0.002), and serum ferritin level was negatively correlated with body mass index (Coefficient, -3.87; 95% CI, -7.57--0.16; p = 0.041). Performance levels were positively correlated with serum vitamin D levels (Coefficients, 7.25; 95% CI, 0.25-14.25; p = 0.043) and negatively correlated with EAT-26 scores (Coefficient, -7.30; 95% CI, -12.61--1.98; p = 0.009) and body fat percentage (Coefficient, -13.26; 95% CI, -24.66--1.86; p = 0.025). Vitamin D and ferritin insufficiencies are prevalent among Japanese female athletics athletes. Serum vitamin D level was related to performance level.

Running performance is crucial for triathlon performance. However, the prior bout of cycling may affect the running split time. This study compared the triathletes' cycling plus running (C+R) time, when cycling was performed at three different intensities and running was maximal. A total of 38 athletes (21 males and 17 females) were included. Body composition, maximal oxygen uptake, and functional threshold power (FTP) was evaluated. The participants visited the laboratory three times to cycle 20 km at 80%, 85%, or 90% FTP (in randomized order) and run 5 km as fast as possible. Males ran faster after cycling at 80% FTP than after cycling at 90% FTP (mean difference=35.1 s; CI% 2.2, 68.1 s; p=0.035). The C+R time was faster when cycling at 90% FTP than at 80% FTP (mean difference=57.7 s; CI% 26.1, 89.3 s; p<0.001). For females, no significant difference was observed in the running time after cycling at 80%, 85%, or 90% FTP. The C+R time was faster when cycling at 90% FTP than at 80% FTP (mean difference=80.9 s; CI% 29.7, 132.1 s; p=0.002). In conclusion, to optimize triathlon performance, male and female athletes should cycle at a minimum of 90% FTP.

This study aims to explore the relationship between blood biochemical indexes and injury risk of elite male athletes in racing ice sports. The male athletes compared the demographic indexes, monthly injuries, and longitudinal tracking data. The non-linear relationship was analyzed using an unrestricted cubic spline. Generalized estimating equations estimated the relative risk (OR) of injury occurrence. Receiver operating characteristics and the area under the curve determined diagnostic accuracy. In the snow sledding group, when creatine kinase rises to 489.46 u/L or Testosterone decreases to 41.32 ng/ml, the risk increases by 1.70 times (OR=1.70, p<0.001) and 1.69 times(OR=1.69, p<0.001) with statistical significance. the Creatine kinase (OR=1.01, P=0.007) and Testosterone (OR=1.00, P＜0.001) were included in the injury prediction model. The model exhibits excellent discrimination, with sensitivity and specificity of 82.8% and 86.5%, respectively. In the ice skating group, when Creatine kinase rise to 467.00 u/L, the risk increases by 2.56 times with statistical significance (OR=2.56, p<0.001). Creatine kinase (OR=1.01, P＜0.001) was included in the predictive model. The model demonstrates good discrimination, with sensitivity and specificity of 90.5% and 66.7%, respectively. Creatine kinase and Testosterone are the risk predictors of injury in elite snowmobile male athletes. Creatine kinase is an independent risk factor for injury in elite speed skaters.