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Purpose: This study aimed to determine whether the initial levels of aerobic fitness and hematological variables in young female road cyclists are related to their athletic performance development during their careers. Methods: Results of graded exercise tests on a cycle ergometer and total hemoglobin mass (tHb-mass) measurements were analyzed in 34 female road cyclists (age 18.6 [1.9] y). Among them, 2 groups were distinguished based on their competitive performance (Union Cycliste Internationale world ranking) over the following 8 years. Areas under the curve in receiver-operating-characteristic curves were calculated as indicators of elite-performance prediction. Results: Initial graded exercise test variables (peak power, peak oxygen uptake, and power at 4 mmol/L blood lactate) were not significantly different in elite (n = 13) versus nonelite (n = 21) riders. In contrast, elite riders had higher tHb-mass expressed either in absolute measures (664 [75] vs 596 [59] g, P =.006) or normalized to body mass (11.2 [0.8] vs 10.3 [0.7] g/kg, P =.001) and fat-free mass (14.4 [0.9] vs 13.1 [0.9] g/kg, P <.001). Absolute and relative erythrocyte volumes were significantly higher in elite subjects (P ranged from <.001 to.006). Of all the variables analyzed, the relative tHb-mass had the highest predictive ability to reach the elite level (area under the curve ranged from.82 to.85). Conclusion: Measurement of tHb-mass can be a helpful tool in talent detection to identify young female road cyclists with the potential to reach the elite level in the future. [ABSTRACT FROM AUTHOR]

Background: Bovine colostrum (COL) is assumed to be one of the strongest natural immune stimulants. Regular ingestion of COL may contribute to improved immune response in athletes exposed to high training loads. Methods: Twenty-eight endurance-trained males aged 31.1 ± 10.2 years (body mass 81.9 ± 9.0 kg; height 1.82 ± 0.06 m) completed this randomized doubleblind placebo(PLA)-controlled crossover study aimed at investigating the effect of 12-week COL supplementation (25gCOL·day-1) on resting (REST), exerciseinduced (POST-EX), and short-term post-exercise recovery (REC; 1 h after test exercise) changes in selected saliva and blood immunoglobulins (Ig), white blood cell (WBC) count and differential; as well as blood hematological, nutritional status and muscle damage indices. The protocol assumed 4 study visits - before/after supplementation with COL (COLPRE and COLPOST) and PLA (PLAPRE and PLAPOST). During testing sessions, incremental rowing test to exhaustion and swimming-specific performance test were introduced as exercise stimuli. Results: At COLPOST visit the secretory IgA (SIgA) concentration in saliva was significantly higher at POST-EX and REC compared to REST (p<0.05). COL supplementation had no effect on blood IgA, IgE, IgD, IgG, and IgM concentrations. Furthermore, after COL supplementation decrease of hematocrit at REC (p<0.05) was revealed. Conclusions: 12-week supplementation with 25 gCOL·day-1 in endurance-trained male athletes resulted in a favorable increase in post-exercise concentration of salivary SIgA. COL seems to be a potential stimulator of local immune defense after exercise-induced homeostasis disturbances. Nevertheless, the lack of effect on blood markers indicates the need for further research in the area of mechanisms underlying the effect of the supposed COL immunological capacity. [ABSTRACT FROM AUTHOR]

High-intensity interval training (HIIT) prescriptions manipulate intensity, duration, and recovery variables in multiple combinations. Researchers often compare different HIIT variable combinations and treat HIIT prescription as a "maximization problem", seeking to identify the prescription(s) that induce the largest acute VO2/HR/RPE response. However, studies connecting the magnitude of specific acute HIIT response variables like work time >90% of VO2max and resulting cellular signalling and/or translation to protein upregulation and performance enhancement are lacking. This is also not how successful endurance athletes train. First, HIIT training cannot be seen in isolation. Successful endurance athletes perform most of their training volume below the first lactate turn point (

Purpose: To measure oxygen demand, uptake, and deficits in competitive cross-country skiers during outdoor roller skiing at different competition durations, ranging from the endurance domain to the sprint domain. Methods: Ten competitive cross-country skiers (6 males; V ˙ O2max 78 ± 3 and 4 females; V ˙ O2max 62 ± 3 mL∙kg−1∙min−1) raced time trials consisting of 1, 2, and 4 laps in a 1.6 km racecourse in a randomized order with 35 min recovery in-between. Oxygen uptake was measured using a wearable metabolic system while oxygen demand was estimated from kinematic data (GPS and IMU) and an athlete-specific model of skiing economy. Skiing economy and V ˙ O2max was established on a separate test day using six submaximal constant-load trials at different speeds and inclines, and one maximal-effort trial on a roller-skiing treadmill. Results: Average oxygen demand was 112 ± 8%, 103 ± 7% and 98 ± 7% of V ˙ O2max during the 1 (3:37 ± 0:20 m:ss), 2 (7:36 ± 0:38 m:ss) and 4 (15:43 ± 1:26 m:ss) lap time trials, respectively, and appeared to follow an inverse relationship with time-trial duration. Average oxygen uptake was unaffected by race length (86 ± 5%, 86 ± 5%, and 86 ± 7% of V ˙ O2max, respectively). Accumulated oxygen deficit at the end of each time trial was 85 ± 13, 106 ± 32 and 158 ± 62 mL∙kg−1, while oxygen deficits per work bout was 23 ± 3, 18 ± 3 and 16 ± 3 mL∙kg−1 for the 1, 2, and 4-lap time trials, respectively. Conclusion: Elite cross-country skiers adjust their pacing strategies from attaining relatively small oxygen deficits per work bout in the endurance domain, to larger deficits in the sprint domain. This indicates a shift in strategy from prioritizing stable work-economy and rate-of-recovery in the endurance domain, to maximizing power output in the sprint domain. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to determine if machine learning models could predict the perceived morning recovery status (AM PRS) and daily change in heart rate variability (HRV change) of endurance athletes based on training, dietary intake, sleep, HRV, and subjective well-being measures. Methods: Self-selected nutrition intake, exercise training, sleep habits, HRV, and subjective well-being of 43 endurance athletes ranging from professional to recreationally trained were monitored daily for 12 weeks (3572 days of tracking). Global and individualized models were constructed using machine learning techniques, with the single best algorithm chosen for each model. The model performance was compared with a baseline intercept-only model. Results: Prediction error (root mean square error [RMSE]) was lower than baseline for the group models (11.8 vs. 14.1 and 0.22 vs. 0.29 for AM PRS and HRV change, respectively). At the individual level, prediction accuracy outperformed the baseline model but varied greatly across participants (RMSE range 5.5–23.6 and 0.05–0.44 for AM PRS and HRV change, respectively). Conclusion: At the group level, daily recovery measures can be predicted based on commonly measured variables, with a small subset of variables providing most of the predictive power. However, at the individual level, the key variables may vary, and additional data may be needed to improve the prediction accuracy. [ABSTRACT FROM AUTHOR]

Adaptations in muscle physiology due to long-term physical training have been monitored using various methods: ranging from invasive techniques, such as biopsy, to less invasive approaches, such as electromyography (EMG), to various quantitative magnetic resonance imaging (qMRI) parameters. Typically, these latter parameters are assessed immediately after exercise. In contrast, this work assesses such adaptations in a set of qMRI parameters obtained at rest in the lumbar spine muscles of volunteers. To this end, we developed a multiparametric measurement protocol to extract quantitative values of (water) T2, fat fraction, T1, and Intra Voxel Incoherent Motion (IVIM) diffusion parameters in the lumbar back muscle. The protocol was applied to 31 healthy subjects divided into three differently trained cohorts: two groups of athletes (endurance athletes and powerlifters) and a control group with a sedentary lifestyle. Significant differences in muscle water T2, fat fraction, and pseudo-diffusion coefficient linked to microcirculatory blood flow in muscle tissue were found between the trained and untrained cohorts. At the same time, diffusion coefficients (resolved along different directions) provided additional differentiation between the two groups of athletes. Specifically, the strength-trained athletes showed lower axial and higher radial diffusion components compared to the endurance-trained cohort, which may indicate muscle hypertrophy. In conclusion, utilizing multiparametric information revealed new insights into the potential of quantitative MR parameters to detect and quantify long-term effects associated with training in differently trained cohorts, even at rest. [ABSTRACT FROM AUTHOR]

Background: Exercise-induced oxidative stress and inflammation can impair muscular function in humans. The antioxidant and anti-inflammatory properties of molecular hydrogen (H2) highlight its potential to be as an effective nutritional supplement to support muscular function performance in healthy adults. However, the effects of H2 supplementation on muscular endurance performance in trained individuals have not been well characterized. This study aimed to assess the effects of intermittent hydrogen-rich water (HRW) supplementation before, during, and after resistance training on muscular endurance performance, neuromuscular status, and subjective perceptual responses after a 48-h recovery period. Methods: This randomized, double-blinded, placebo-controlled cross-over study included 18 trained men aged 19.7 ± 0.9 years. Participants in this study were instructed to consume 1,920 mL of HRW or pure water (Placebo) daily for 7 days. Additionally, participants were required to supplement with HRW or pure water five times during the training day (1,260 mL total). This included drinking 210 mL 30 min and 1 min before training, 210 mL between training sets, 210 mL immediately after training, and 420 mL 30 min into the recovery period. Participants performed half-squat exercises with the load set at 70% of one repetition maximum for six sets (half-squat exercise performed to repetitions failure each set). We measured the power output and number of repetitions in the free barbell half-squat used to assess muscular endurance performance in participants. The countermovement jump (CMJ) height, total quality recovery scale (TQRS), and muscle soreness visual analog scale (VAS) scores were measured to assess fatigue recovery status after training, as well as at 24 and 48 h of recovery. Results: The total power output (HRW: 50,866.7 ± 6,359.9W, Placebo: 46,431.0 ± 9,376.5W, p = 0.032) and the total number of repetitions (HRW:78.2 ± 9.5 repetitions, Placebo: 70.3 ± 9.5 repetitions, p = 0.019) in the H2 supplemented group were significantly higher than in the placebo group. However, there was no statistically significant difference (p< 0.05) between the H2 and placebo groups in CMJ, TQRS, and VAS. Conclusion: Eight days of intermittent HRW intake could significantly improve muscular endurance performance in trained individuals, making it a promising strategy for athletes or fitness enthusiasts looking to boost muscular endurance during resistance training or competitions. However, it should be noted that HRW intake alone may not be adequate to accelerate recovery from muscle soreness or fatigue following high-intensity training. [ABSTRACT FROM AUTHOR]

Summary Burgeoning interest in marathons necessitates an understanding of performance determinants. Research has highlighted the importance of diet, training and sleep, yet relations of circadian preference and sleep inertia with marathon performance remain largely unexplored. Because marathons generally start early‐to‐mid morning, these characteristics may have relevant impact. This study investigates relationships of circadian preference, sleep inertia and their interaction with marathon completion time. Consenting participants in a 2016 large mass‐participation city marathon completed self‐report questionnaires capturing circadian preference and sleep inertia, along with demographics and other characteristics. Circadian preference and sleep inertia were described across subgroups. Analyses examined the associations and interactions of circadian preference and sleep inertia with marathon completion times, with adjusted analyses accounting for age, sex and sleep health. Participants were marathon finishers (n = 936; 64.5% male; 66.3% young‐adults), with a majority reporting morningness tendencies (60.8%). Results supported a linear association between increasing eveningness preference with slower marathon times (p = 0.003; padjusted = 0.002), while some support was provided for a linear relationship between greater sleep inertia and slower marathon times (p = 0.04; padjusted = 0.07). A significant interaction was observed (p = 0.02; padjusted = 0.01), with the directionality suggesting that the circadian preference relationship weakened when sleep inertia severity increased, and vice‐versa. Our results suggest deleterious associations of increasing eveningness preference and greater sleep inertia with marathon completion time. These features may aid identifying marathoners who could be at a disadvantage, while also serving as modifiable targets for personalized training regimens preceding competition. [ABSTRACT FROM AUTHOR]

Background: Nicotinamide adenine dinucleotide (NAD+), nicotinamide adenine dinucleotide phosphate (NADP+), and their reduced forms (NADH and NADPH) are the vital cofactors for most cellular oxidation/reduction reactions and therefore influence most critical pathways in cellular metabolism. This study aimed to predict the trends of age-related changes in erythrocyte NAD+ and NADP+ concentrations in elite athletes compared to untrained controls and to assess whether life-long physical training stimulates favorable adaptations in erythrocyte NAD(P)+ concentrations. Methods: Erythrocyte concentrations of NAD+ and NADP+ were measured in 68 elite endurance runners (20–81 years), 58 elite sprinters (21–90 years), and 62 untrained individuals (20–68 years). Linear regression analyses were performed to estimate longitudinal relationships and cross-sectional rates of change between age and erythrocyte NAD+ and NADP+ levels. One-way analysis of variance was used to determine differences between the studied groups. Results: In all three groups, the erythrocyte NAD+ and NADP+ concentrations significantly decreased with advancing age, suggesting gradual deterioration of NAD-related regulatory functions in older individuals. However, the concentration of erythrocyte NAD(P)+, regardless of age category, was higher in the athletic groups compared to less active controls. Conclusions: Our research shows that systematic sports participation, especially of a sprint-oriented nature, can be treated as a natural and effective strategy promoting cellular NAD(P)+ anabolism and thus cells' energy and redox metabolism. Trial registration: The study was retrospectively registered in the clinical trials registry on 2021-11-09 (NCT05113914). [ABSTRACT FROM AUTHOR]

Background/Objectives: Energy availability (EA) is essential for maintaining physiological functions, significantly influencing athletes' health and performance. Nutritional behaviors, however, vary across sports. This study aims to assess EA levels in athletes from different disciplines, focusing on the relationship between EA and body composition in endurance athletes compared to rugby players. Methods: This study involved 18 endurance athletes (15 men, 3 women) and 36 rugby players (all men). Data were gathered through interviews, questionnaires, and bioimpedance analysis. Energy intake (EI) was measured with a 24 h dietary recall, and exercise energy expenditure (EEE) was calculated using the IPAQ questionnaire. EA was calculated as EA = (EI − EEE)/fat-free mass (FFM), with results categorized into clinical, subclinical, and optimal ranges. Results: The endurance group had a lower average FFM (57.81 kg) compared to the rugby players (67.61 kg). EA was also significantly lower in endurance athletes (11.72 kcal/kg FFM) than in rugby players (35.44 kcal/kg FFM). Endurance athletes showed more restrictive nutritional behavior with lower EI and higher EEE, but both groups maintained body composition within normal ranges. Conclusions: Endurance athletes exhibit greater nutritional restrictions compared to rugby players, though their body composition remains healthy. Further research is required to investigate the long-term effects of low EA on performance, injury risk, and potential impairment when EA falls below the optimal threshold of 45 kcal/kg FFM/day. [ABSTRACT FROM AUTHOR]

Peak oxygen pulse (O2Ppeak) is an important index of cardiorespiratory fitness (CRF). The FRIEND database is a global source of reference values for CRF. However, no reference equation is tailored for endurance athletes (EA) to predict O2Ppeak. Here, we adjusted the well-established FRIEND equation for O2Ppeak to the characteristics of the EA population. 32 (34.0%) female EA and 62 (66.0%) male well-trained EA underwent maximal cardiopulmonary exercise test on a treadmill. V̇O2max was 4.5 ± 0.5 L min−1 in males and 3.1 ± 0.4 L min−1 in females. O2Ppeak was 23.6 ± 2.8 mL beat−1 and 16.4 ± 2.0 mL beat−1 for males and females, respectively. Firstly, we externally validated the original FRIEND equation. Secondly, using multiple linear regression, we adjusted the FRIEND equation for O2Ppeak to the population of EA. The original FRIEND equation underestimated O2Ppeak for 2.9 ± 2.9 mL beat−1 (P <.001) in males and 2.2 ± 2.1 mL beat−1 (P <.001) in females. The updated equation was 1.36 + 1.07 (23.2 · 0.09 · age − 6.6 [if female]). The new equation explained 62% of the variance and significantly predicted O2Ppeak (R2 = 0.62, β = 0.78, P <.001). The error of the EA-adjusted model was 0.1 ± 2.9 mL beat−1 (P =.82) and 0.2 ± 2.1 mL beat−1 (P =.65) for males and females respectively. Recalibration of the original FRIEND equation significantly enhances its accuracy among EA. The error of the EA-adjusted model was negligible. A new recalibrated equation should be used to predict O2Ppeak in the population of EA. [ABSTRACT FROM AUTHOR]

Introduction: Prolonged and repeated exercise performed during an ultraendurance event can induce general and cardiac fatigue known as exerciseinduced cardiac fatigue. Our objective was to find a possible correlation between the cardiac function and the autonomic cardiac function. Methods: During a multistage ultra-endurance event, a female well-trained cyclist underwent daily rest echocardiography and heart rate variability measurements to assess the cardiac function and the cardiac autonomic function. Results: The athlete completed 3,345 km at 65% of her maximum heart rate and 39% of her maximum aerobic power. A progressive improvement of the systolic function for both the left ventricle and the right ventricle was observed during the event. Discussion: Alterations were observed on the cardiac autonomic function with an imbalance between sympathetic and parasympathetic, but there was no sign of a significant correlation between the cardiac function and the autonomic cardiac function and no signs of cardiac fatigue either. Further analysis should be performed on a larger sample to confirm the obtained results. [ABSTRACT FROM AUTHOR]

Given the failure of high-density lipoprotein (HDL) raising therapies to reduce cardiovascular disease risk, attention has turned towards HDL composition and vascular protective functions. In individuals with insulin resistance, exercise interventions recover HDL function. However, the effect of exercise on HDL in otherwise healthy individuals is unknown. This cross-sectional study aimed to measure HDL composition and antioxidant/endothelial anti-inflammatory function in insulin sensitive endurance athlete and healthy control men. HDL was isolated using density gradient ultracentrifugation. HDL composition was measured using microplate assays for apolipoprotein A-I, total cholesterol content and apolipoprotein M. HDL protein composition was measured using nano-liquid chromatography tandem mass spectrometry. HDL subclass distribution was measured by native gel electrophoresis. HDL in vitro antioxidant function was measured by paraoxonase-1 activity assay and anti-inflammatory function assessed in endothelial cells. Compared with controls, endurance athlete HDL had higher apolipoprotein A-1 (1.65 + 0.62 mg/ml vs 1.21 - 0.34 mg/ml, P=0.028) and higher total cholesterol content (2.09 - 0.44 mmol/L vs 1.54 + 0.33 mmol/L, P<0.001). Proteomics revealed higher apolipoprotein A-II, A-IV and D and transthyretin in endurance athlete HDL versus controls. There was no difference observed in in vitro HDL antioxidant or anti-inflammatory functions between controls and endurance athletes. Despite a more favourable composition, endurance athlete HDL did not have higher in vitro antioxidant or anti-inflammatory function. It is possible that HDL has a ceiling of function, i.e. that healthy HDL function cannot be enhanced by endurance exercise. [ABSTRACT FROM AUTHOR]

Background: This study used metabolic phenotyping to explore the responses of highly-trained cross-country skiers to a standardized exercise test, which was part of the athletes' routine testing, and determine whether metabolic phenotyping could discriminate specific physiological, performance, and illness characteristics. Methods: Twenty-three highly-trained cross-country skiers (10 women and 13 men) participated in this study. Capillary whole-blood samples were collected before (at rest) and 2.5 min after (post-exercise) a roller-ski treadmill test consisting of 5–6 × 4-min submaximal stages followed by a self-paced time trial (~ 3 min) and analyzed using mass spectrometry. Performance level was defined by International Ski Federation distance and sprint rankings. Illness data were collected prospectively for 33 weeks using the Oslo Sports Trauma Research Center Questionnaire on Health Problems. Orthogonal partial least squares-discriminant analyses (OPLS-DA) followed by enrichment analyses were used to identify metabolic phenotypes of athlete groups with specific physiological, performance, and illness characteristics. Results: Blood metabolite phenotypes were significantly different after the standardized exercise test compared to rest for metabolites involved in energy, purine, and nucleotide metabolism (all OPLS-DA p < 0.001). Acute changes in the metabolic phenotype from rest to post-exercise could discriminate athletes with: (1) higher vs. lower peak blood lactate concentrations; (2) superior vs. inferior performance levels in sprint skiing, and (3) ≥ 2 vs. ≤ 1 self-reported illness episodes in the 33-week study period (all p < 0.05). The most important metabolites contributing to the distinction of groups according to (1) post-exercise blood lactate concentrations, (2) sprint performance, and (3) illness frequency were: (1) inosine, hypoxanthine, and deoxycholic acid, (2) sorbitol, adenosine monophosphate, and 2-hydroxyleuroylcarnitine, and (3) glucose-6-phosphate, squalene, and deoxycholic acid, respectively. Conclusion: Metabolic phenotyping discriminated between athlete groups with higher vs. lower post-exercise blood lactate concentrations, superior vs. inferior sprint skiing performance, and more vs. less self-reported illnesses. While the biological relevance of the identified biomarkers requires validation in future research, metabolic phenotyping shows promise as a tool for routine monitoring of highly-trained endurance athletes. Key Points: • The standardized exercise test led to alterations in metabolites primarily involved in carbohydrate metabolism and the tricarboxylic acid cycle, purine/pyrimidines, and nucleoside/nucleotides. • Acute changes in metabolic phenotypes could differentiate athletes with higher vs. lower [La-]peak and superior vs. inferior sprint skiers, and between athletes who were susceptible vs. non-susceptible to illness. • Metabolic phenotyping shows promise as a tool for routine monitoring of endurance athletes if cost and turnaround time is improved. [ABSTRACT FROM AUTHOR]

Determining an athlete's maximal peak power (MPP) is crucial in profiling endurance sports participants. While short (3 to 6 seconds) all-out efforts have been validated for MPP assessment, prior studies mainly involved non-endurance trained athletes. This study aimed to assess the intra- and inter-day reliability of a 6-second Wingate test for MPP determination in endurance athletes. Endurance-trained participants (22 males, 5 females) completed nine 6-second Wingate tests over four days (3 trials at baseline, 2 trials on each subsequent day). Analysis revealed no systematic differences in MPP (F(4.09, 106.3) = 1.88, p = 0.117) or time to peak power (χ2 (8) = 5.23, p = 0.732) across the trials. Reliability, assessed through the intraclass correlation coefficient (ICC) and standard error of measurement (SEM), was excellent across all trials (ICC = 0.95, SEM = 40.0W, SEM% = 3.7%). Absolute reliability improved when selecting the average or the best MPP values from each day (SEM% = 2.7% and 2.9%, respectively). Within-day reliability was consistently rated as excellent, with the best values on the 4th day of tests. No significant differences in MPP values occurred between the first and second 6-second Wingate tests on days 1 to 3, with both trials demonstrating similar reliability values (SEM%: 3.2% vs 2.8%, for the first and second trials, respectively). The test also demonstrated a good sensitivity to detect a meaningful change in MPP values. In conclusion, the 6-second Wingate test proves reliable for determining MPP in endurance-trained athletes. Two trials are recommended on the first day of testing, with a single MPP likely sufficient to determine the athlete's MPP on subsequent days. [ABSTRACT FROM AUTHOR]

ACTN3 R577X and ACE I/D polymorphisms are associated with endurance exercise ability. This case–control study explored the association of ACTN3 and ACE gene polymorphisms with elite pure endurance in Korean athletes, hypothesizing that individuals with both ACTN3 XX and ACE II genotypes would exhibit superior endurance. We recruited 934 elite athletes (713 males, 221 females) and selected 45 pure endurance athletes (36 males, 9 females) requiring "≥90% aerobic energy metabolism during sports events", in addition to 679 healthy non-athlete Koreans (361 males, 318 females) as controls. Genomic DNA was extracted and genotyped for ACTN3 R577X and ACE I/D polymorphisms. ACE ID (p = 0.090) and ACTN3 RX+XX (p = 0.029) genotype distributions were significantly different between the two groups. Complex ACTN3-ACE genotypes also exhibited significant differences (p = 0.014), with dominant complex genotypes positively affecting endurance (p = 0.039). The presence of RX+II or XX+II was associated with a 1.763-fold higher likelihood of possessing a superior endurance capacity than that seen in healthy controls (90% CI = 1.037–3.089). Our findings propose an association of combined ACTN3 RX+XX and ACE II genotypes with enhanced endurance performance in elite Korean athletes. While causality remains to be confirmed, our study highlights the potential of ACTN3-ACE polymorphisms in predicting elite endurance. [ABSTRACT FROM AUTHOR]

Objective: The main objective of this study was to compare lactate thresholds and aerobic capacity from a graded-intensity exercise test (GXT) for near-infrared spectroscopy measurements in healthy, untrained individuals and highly trained athletes. Methods: This study included 29 untrained students (13 females) and 27 highly trained speed skaters (13 females). A maximal effort GXT was performed on a cycloergometer. The lactate-based aerobic and anaerobic thresholds, and the corresponding thresholds for muscle oxygen saturation (SmO2), were determined. Results: The power values determined for all thresholds were significantly higher in female and male speed skaters compared to male and female college students. SmO2 at anaerobic thresholds was significantly lower in female speed skaters than in female students. Both female and male skaters showed greater changes in SmO2 after the GXT compared to students. The recovery did not significantly differ between groups within gender. There was a significant positive correlation in females between the rate of muscle reoxygenation and VO2max power (r = 0.610). In speed skaters, the rate of muscle reoxygenation was not significantly higher than students and correlated positively with VO2max (r = 0.449). Conclusions: The SmO2 at the exercise thresholds, during and after maximal exercise, depends on the training status of the individual. The participants with a higher physical fitness level showed greater decreases in ΔSmO2 at the AT level, as well as after maximal exercise. SmO2 corresponding to the well-established exercise thresholds may be applied to guide training prescription. The rate of muscle reoxygenation after a GXT was also dependent on the aerobic capacity of the participants. [ABSTRACT FROM AUTHOR]

Physical activity is recommended for the prevention of primary and secondary cardiovascular (CV) disease as it is linked to a number of health benefits, especially CV. However, recent research suggests that high-volume, long-term endurance exercise may hasten rather than slow the coronary atherosclerosis progression. This contentious theory has generated a great discussion and is still a major source of doubt when it comes to the clinical treatment of coronary artery disease (CAD) in athletes. CAD is the primary cause of sudden cardiac death in athletes over 35 years. Thus, recent studies evaluated the prevalence of CAD in athletes and its clinical and prognostic implications. Indeed, many studies have shown a relationship between endurance sports and higher volumes of coronary calcified plaque as determined by computed tomography. However, the precise pathogenetic substrate for the existence of an increased coronary calcification burden among endurance athletes remains unclear. Moreover, the idea that coronary plaques in elite athletes present a benign morphology has been cast into doubt by some recent studies showing potential association with adverse cardiovascular events. This review aims to analyze the association between physical activity and CAD, explaining possible underlying mechanisms of atherosclerotic progression and non-ischemic coronary lesions, focusing primarily on clinical and prognostic implications, multimodal evaluation, and management of CAD in endurance athletes. [ABSTRACT FROM AUTHOR]

Purpose: Endurance elite athletes are expected to present a cardiac remodelling, characterized by eccentric hypertrophy (EH), may be associated with higher sportive performances. However, not all can present a cardiac remodelling. The study aimed to identify endurance athletes without cardiac remodelling characterizing their physiologic and clinical features. Methods: We studied 309 endurance athletes (cycling, rowing, canoeing, triathlon, athletics, long-distance swimming, cross-country skiing, mid-long distance track, pentathlon, biathlon, long-distance skating and Nordic-combined) examined during period of training, by clinical evaluation, ECG, echocardiogram and exercise-stress test. Sport career achievements (Olympic\World championship medals or national\world records) were recorded. Results: EH was found in most of athletes, (n = 126, 67% of males; n = 85, 68.5% of females). A significant proportion,, exhibited normal geometry (NG) (n = 59, 31.3% in males; n = 39, 31.4% in females). At stress test, significant differences between EH and NG athletes were found in peak power (317.1 ± 71.2W in NG vs. 342.2 ± 60.6W in EH, p = 0.014 in males and 225.1 ± 38.7W in NG vs. 247.1 ± 37W in EH, p = 0.003 in females), rest heart rate (66.1 ± 13 in NG vs. 58.6 ± 11.6 in EH, p = 0.001 in males and 68 ± 13.2 in NG vs. 59.2 ± 11.2 in EH, p = 0.001 in females) with similar ventricular extrasystoles (p = 0.363 in males and p = 0.492 in females). However, no significant differences in athletic achievements were registered. Conclusion: Our study demonstrates a relatively high prevalence of NG in endurance athletes, in addition to the expected EH. Athletes with NG perform worse in exercise-stress test and exhibit some less advantageous functional heart characteristics. However, the type of heart geometry is not associated with negative clinical findings. [ABSTRACT FROM AUTHOR]

Introduction: Although neuromuscular function varies significantly between strength and endurance-trained adult athletes, it has yet to be ascertained whether such differences manifest by early adolescence. The aim of the present study was to compare knee extensor neuromuscular characteristics between adolescent athletes who are representative of strength (wrestling) or endurance (triathlon) sports. Methods: Twenty-three triathletes (TRI), 12 wrestlers (WRE) and 12 untrained (CON) male adolescents aged 13 to 15 years participated in the present study. Maximal voluntary isometric contraction (MVIC) knee extensor (KE) torque was measured, and 100-Hz magnetic doublets were delivered to the femoral nerve during and after KE MVIC to quantify the voluntary activation level (%VA). The doublet peak torque (T100Hz) and normalized vastus lateralis (VL) and rectus femoris (RF) EMG (EMG/M-wave) activities were quantified. VL and RF muscle architecture was also assessed at rest using ultrasound. Results: Absolute and relative (to body mass) KE MVIC torques were significantly higher in WRE than TRI and CON (p < 0.05), but comparable between TRI and CON. No significant differences were observed between groups for %VA, T100Hz or either VL or RF muscle thickness. However, VL EMG/M-wave was higher, RF fascicle length longer, and pennation angle smaller in WRE than TRI and CON (all p < 0.05). Conclusion: The wrestlers were stronger than triathletes and controls, potentially as a result of muscle architectural differences and a greater neural activation. Neuromuscular differences can already be detected by early adolescence in males between predominantly endurance and strength sports, which may result from selection bias and/or physical training. [ABSTRACT FROM AUTHOR]

Purpose: The aim was to study if aerobic capacity varies during different phases of the menstrual cycle (MC) in endurance-trained female athletes. Methods: Ten endurance-trained eumenorrheic women performed a submaximal test followed by an incremental test until exhaustion three times during one MC, early follicular phase (EFP), late follicular phase (LFP), and midluteal phase (MLP). During the submaximal test, the respiratory exchange ratio (RER) and utilization of fat and carbohydrates were analyzed; and, during the incremental test, VO2 peak, maximal heart rate, utilization of fat and carbohydrates, and RER were analyzed. Lactate levels were analyzed at rest, during the submaximal test, and after the incremental test. The anaerobic threshold was determined at RER = 1. Results: No significant differences (p <.05) between the MC phases were seen in a maximal heart rate or VO2peak. Similarly, VO2, heart rate, RER, fatty acid oxidation, and carbohydrate oxidation at 70, 80, 90, and 100% of VO2peak did not differ significantly between MC phases. There were no significant differences between these phases in resting lactate before the test or during the submaximal tests, though there was a significant difference in lactate concentration 3 minutes after the incremental test between the EFP and the LFP (p =.043). Conclusion: This study did not display variations in physiological parameters between EFP, LFP, and MLP, indicating similar aerobic capacity despite hormonal variations. This knowledge may be useful when planning for competition in aerobic events. [ABSTRACT FROM AUTHOR]

Post‐exercise hot (HWI) and cold (CWI) water immersion are popular strategies used by athletes in a range of sporting contexts, such as enhancing recovery or adaptation. However, prolonged heating bouts increase neuroendocrine responses that are associated with perceptions of fatigue. Fourteen endurance‐trained runners performed three trials consisting of two 45‐min runs at 95% lactate threshold on a treadmill separated by 6 h of recovery. Following the first run, participants completed one of HWI (30 min, 40°C), CWI (15 min, 14°C) or control (CON, 30 min rest in ambient conditions) in a randomised order. Perceived effort and recovery were measured using ratings of perceived exertion (RPE) and the Acute Recovery and Stress Scale (ARSS), whilst physiological responses including venous concentrations of a range of neuroendocrine markers, superficial femoral blood flow, heart rate and rectal temperature were measured. Exercise increased neuroendocrine responses of interleukin‐6, adrenaline and noradrenaline (all P < 0.001). Additionally, perceptions of overall recovery (P < 0.001), mental performance capacity (P = 0.02), physical performance capability (P = 0.01) and emotional balance (P = 0.03) were reduced prior to the second run. However, there was no effect of condition on these variables (P > 0.05), nor RPE (P = 0.68), despite differences in rectal temperature, superficial femoral blood flow following the first run, and participants' expected recovery prior to the intervention (all P < 0.001). Therefore, athletes may engage in post‐exercise hot or cold‐water immersion without negatively impacting moderate‐intensity training sessions performed later the same day. What is the central question of this study?Does post‐exercise heating or cooling alter recovery and perception of effort during subsequent exercise?What is the main finding and its importance?Neither post‐exercise heating nor post‐exercise cooling altered perceived recovery or perception of effort during subsequent exercise, despite heating inducing large increases in blood flow to the lower limbs. Contrary to our hypotheses, neither heating nor cooling had any impact on inflammatory or neuroendocrine responses in plasma. Post‐exercise heating does not appear to exacerbate fatigue as previously suggested in other studies. [ABSTRACT FROM AUTHOR]

This article provides an overview of the development of Scandinavian exercise physiology, with a focus on the years between 1910 and 1920 and the subsequent establishment of the Rockefeller Institute in Copenhagen in 1928. Three scientists, Erik Hohwü Christensen, Marius Nielsen, and Erling Asmussen, played key roles in advancing the field during this time. Their research centered on the adaptative resetting of homeostasis across organ systems during exercise. The article also mentions the League of Nations' Health Organization's support for a research program investigating physiological responses to maximum muscular effort, which further bolstered the work of Hohwü and Nielsen. The text goes on to discuss the collaborative efforts of Hohwü, Nielsen, and Asmussen in the 1930s and 1940s, where they conducted experiments to understand the mechanisms behind the increase in cardiac output during exercise. Their studies revealed that cardiovascular function, ventilation, and thermoregulation are tightly regulated during exercise, with feedback mechanisms originating within the working skeletal muscle. Additionally, they identified a neural feedback mechanism related to the volume of involved musculature that triggers these responses. Overall, the collaboration between these three scientists led to significant advancements in the understanding of exercise physiology. [Extracted from the article]

Background: Structural changes in the lower limb's arterial wall in amateur endurance runners are a rare incidental finding, represented just by several case reports. Aim: Study the incidence of non-atherosclerotic lower limb artery wall changes in defined group of amateur endurance runners and identify relationship with the training parameters and the relevant biochemical markers. Methods: Amateur male athletes engaged in endurance running for more than 5 years were enrolled. Tibial and anterior popliteal arteries on each side were examined by ultrasound with focus on non-atherosclerotic structural wall changes: intima-medial border blurring, presence and character of non-atherosclerotic noduli. Subsequently the descriptive and correlation analysis were performed. Results: The study enrolled 20 amateur male endurance runners from Black Swan Triathlon Club Slovakia. The low atherosclerotic risk was represented by normal lipid levels, BMI under 30 kg/m2 and non-smokers in all participants. At least one type of structural artery wall abnormality (noduli or intima-medial border blurring) was present in 19 of 20 participants (95%). The most present was the intima-medial blurring. (80% of participants). The noduli were present in 65% of study group, in almost 40% of these, they were considered as hyperechogenic. All these affections were predominantly in popliteal artery area (65%). The vast majority has bilateral affection. We find a mild correlation between these ultrasound findings and training load represented by annual kilometers and run hours. There was no association between these changes and lipid spectrum or CRP level. Conclusion: The subclinical lower limb artery changes, represented by intima-medial border blurring and non-atherosclerotic noduli were present in almost every amateur endurance runner. Despite the underlying mechanism is not understood, the increased training load seems to be one of the responsible factors. [ABSTRACT FROM AUTHOR]

In a 77-year-old former world-record-holding male marathoner (2:08:33.6), this study sought to investigate the impact of lifelong intensive endurance exercise on cardiac structure, function, and the trajectory of functional capacity (determined by maximal oxygen consumption, V̇ o 2max) throughout the adult lifespan. As a competitive runner, our athlete (DC) reported performing up to 150–300 miles/wk of moderate-to-vigorous exercise and sustained 10–15 h/wk of endurance exercise after retirement from competition. DC underwent maximal cardiopulmonary exercise testing in 1970 (aged 27 yr), 1991 (aged 49 yr), and 2020 (aged 77 yr) to determine V̇ o 2max. At his evaluation in 2020, DC also underwent comprehensive cardiac assessments including resting echocardiography, and resting and exercise cardiac magnetic resonance to quantify cardiac structure and function at rest and during peak supine exercise. DC's V̇ o 2max showed minimal change from 27 yr (69.7 mL/kg/min) to 49 yr (68.1 mL/kg/min), although it eventually declined by 36% by the age of 77 yr (43.6 mL/kg/min). DC's V̇ o 2max at 77 yr, was equivalent to the 50th percentile for healthy 20- to 29-yr-old males and 2.4 times the requirement for maintaining functional independence. This was partly due to marked ventricular dilatation (left-ventricular end-diastolic volume: 273 mL), which facilitates a large peak supine exercise stroke volume (200 mL) and cardiac output (22.2 L/min). However, at the age of 78 yr, DC developed palpitations and fatigue and was found to be in atrial fibrillation requiring ablation procedures to revert his heart to sinus rhythm. Overall, this life study of a world champion marathon runner exemplifies the substantial benefits and potential side effects of many decades of intense endurance exercise. NEW & NOTEWORTHY: This life study of a 77-yr-old former world champion marathon runner exemplifies the impact of lifelong high-volume endurance exercise on functional capacity (V̇ o 2max equivalent to a 20- to 29-yr-old), partly due to extreme ventricular remodeling that facilitates a large cardiac output during exercise despite reduced maximal heart rate. Although it is possible that this extreme remodeling may contribute to developing atrial fibrillation, the net benefits of extreme exercise throughout this athlete's lifespan favor increased health span and expected longevity. [ABSTRACT FROM AUTHOR]

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Abstract Peak oxygen pulse (O2Ppeak) is an important index of cardiorespiratory fitness (CRF). The FRIEND database is a global source of reference values for CRF. However, no reference equation is tailored for endurance athletes (EA) to predict O2Ppeak. Here, we adjusted the well-established FRIEND equation for O2Ppeak to the characteristics of the EA population. 32 (34.0%) female EA and 62 (66.0%) male well-trained EA underwent maximal cardiopulmonary exercise test on a treadmill. V̇O2max was 4.5 ± 0.5 L min−1 in males and 3.1 ± 0.4 L min−1 in females. O2Ppeak was 23.6 ± 2.8 mL beat−1 and 16.4 ± 2.0 mL beat−1 for males and females, respectively. Firstly, we externally validated the original FRIEND equation. Secondly, using multiple linear regression, we adjusted the FRIEND equation for O2Ppeak to the population of EA. The original FRIEND equation underestimated O2Ppeak for 2.9 ± 2.9 mL beat−1 (P

Abstract Background This study used metabolic phenotyping to explore the responses of highly-trained cross-country skiers to a standardized exercise test, which was part of the athletes’ routine testing, and determine whether metabolic phenotyping could discriminate specific physiological, performance, and illness characteristics. Methods Twenty-three highly-trained cross-country skiers (10 women and 13 men) participated in this study. Capillary whole-blood samples were collected before (at rest) and 2.5 min after (post-exercise) a roller-ski treadmill test consisting of 5–6 × 4-min submaximal stages followed by a self-paced time trial (~ 3 min) and analyzed using mass spectrometry. Performance level was defined by International Ski Federation distance and sprint rankings. Illness data were collected prospectively for 33 weeks using the Oslo Sports Trauma Research Center Questionnaire on Health Problems. Orthogonal partial least squares-discriminant analyses (OPLS-DA) followed by enrichment analyses were used to identify metabolic phenotypes of athlete groups with specific physiological, performance, and illness characteristics. Results Blood metabolite phenotypes were significantly different after the standardized exercise test compared to rest for metabolites involved in energy, purine, and nucleotide metabolism (all OPLS-DA p

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: The primary objective of this study was to investigate the impact of varying rest interval durations in High-Intensity Interval Training (HIIT) on several physiological parameters: Excess Post-Exercise Oxygen Consumption (EPOC), Heart Rate Recovery (HRR), body composition, Ventilatory Threshold (VT) and Respiratory Compensation Point (RCP) in endurance athletes over an 8-week period. The study also aims to identify which of these variables is most sensitive to changes in HIIT rest interval duration. Methodology: The study involved a sample of 20 male athletes, with an average age of 21.9 ± 2.61 years, height of 171 ± 4.51 cm, and weight of 63.75 ± 5.11 kg. Participants were divided into two groups (N = 10 per group) and underwent pre-tests before participating in 16 sessions of HIIT with distinct rest protocols: Group 1 had a 2-min active recovery at 70% vOBLA, while Group 2 had a 3-min active recovery at 70% vOBLA. The work interval was 4*8 min (at 80% vVO2max in weeks 1–4, and 8 interval sessions as 4*4 min in (at 95% vVO2max) in weeks 5–8. Post-tests were conducted following the training sessions. Results: Paired t test analysis revealed significant effects (p < 0.05) in all the variables in both groups, except for lean mass and resting heart rate; suggesting a positive adaptation following both the protocols. Analysis of variance (ANOVA) showed no statistically significant differences between the two groups (p > 0.05). Conclusion: The findings suggest that both HIIT protocols had a significant effect on EPOC, HRR after 2 and 3 min, body composition, VT and RCP over the 8-week period. However, the groups were not different from one another, which means that the shorter rest interval of 2 or 3 min of same intensity works equally on all variables and suggests that efficacy of a HIIT protocol is independent of short rest interval durations (2 or 3 min). Registration: Registration was done prospectively (CTRI No.: CTRI/2021/09/036585); Date—Sept 15, 2021. [ABSTRACT FROM AUTHOR]

The present article aimed to systematically summarize primary school-based intervention programs and their effects evaluated through randomized-controlled trial design. A systematic review of relevant articles was carried out using 4 electronic databases. From a total of 193 studies initially found, 30 were included in the qualitative synthesis. Main results: (1) Intensive interval training or jump/strength exercises may positively influence physical fitness, promoting challenging task, psychological needs, and guided styles to a greater extent; (2) Games that demand more cognitive function seem more beneficial than those based on repetitive aerobic exertion to improve fundamental motor skills; (3) The jumping/strength exercises may cause benefits in bone area and bone mineral density, while flexibility and balance may reduce the risk of muscle injury; and (4) Programming a greater dose of moderate-to-vigorous physical activity seems to be related to positive effects in core executive function and academic performance. Additionally, providing information and involving the social environment may enhance the positive effects. [ABSTRACT FROM AUTHOR]

Abstract Background Endurance athletes (EA) are an emerging population of focus for cardiovascular health. The oxygen uptake efficiency plateau (OUEP) is the levelling-off period of ratio between oxygen uptake (VO2) and ventilation (VE). In the cohort of EA, we externally validated prediction models for OUEP and derived with internal validation a new equation. Methods 140 EA underwent a medical assessment and maximal cycling cardiopulmonary exercise test. Participants were 55% male (N = 77, age = 21.4 ± 4.8 years, BMI = 22.6 ± 1.7 kg·m− 2, peak VO2 = 4.40 ± 0.64 L·min− 1) and 45% female (N = 63, age = 23.4 ± 4.3 years, BMI = 22.1 ± 1.6 kg·m− 2, peak VO2 = 3.21 ± 0.48 L·min− 1). OUEP was defined as the highest 90-second continuous value of the ratio between VO2 and VE. We used the multivariable stepwise linear regression to develop a new prediction equation for OUEP. Results OUEP was 44.2 ± 4.2 mL·L− 1 and 41.0 ± 4.8 mL·L− 1 for males and females, respectively. In external validation, OUEP was comparable to directly measured and did not differ significantly. The prediction error for males was − 0.42 mL·L− 1 (0.94%, p = 0.39), and for females was + 0.33 mL·L− 1 (0.81%, p = 0.59). The developed new prediction equation was: 61.37–0.12·height (in cm) + 5.08 (for males). The developed model outperformed the previous. However, the equation explained up to 12.9% of the variance (R = 0.377, R2 = 0.129, RMSE = 4.39 mL·L− 1). Conclusion OUEP is a stable and transferable cardiorespiratory index. OUEP is minimally affected by fitness level and demographic factors. The predicted OUEP provided promising but limited accuracy among EA. The derived new model is tailored for EA. OUEP could be used to stratify the cardiorespiratory response to exercise and guide training.

Circulating blood is an important plasma free amino acids (PFAAs) reservoir and a pivotal link between metabolic pathways. No comparisons are available between athletes with opposite training adaptations that include a broader spectrum of both proteinogenic and non-proteinogenic amino acids, and that take into account skeletal muscle mass. We hypothesized that the levels of the exercise-induced PFAAs concentration are related to the type of training-related metabolic adaptation. We compared highly trained endurance athletes (n = 11) and sprinters (n = 10) aged 20‒35 years who performed incremental exercise until exhaustion. Venous blood was collected before and during the test and 30-min recovery (12 samples). Forty-two PFAAs were assayed using LC-ESI-MS/MS technique. Skeletal muscle mass was estimated using dual X-ray absorptiometry method. Glutamine and alanine were dominant PFAAs throughout the whole exercise and recovery period (~350‒650 μmol∙L-1). Total, combined proteinogenic, non-essential, and non-proteinogenic PFAAs levels were significantly higher in endurance athletes than sprinters (ANOVA group effects: p = 0.007, η2 = 0.321; p = 0.011, η2 = 0.294; p = 0.003, η2 = 0.376; p = 0.001, η2 = 0.471, respectively). The exercise response was more pronounced in endurance athletes, especially for non-proteinogenic PFAAs (ANOVA interaction effect: p = 0.038, η2 = 0.123). Significant between-group differences were observed for 19 of 33 PFAAs detected, including 4 essential, 7 non-essential, and 8 non-proteinogenic ones. We demonstrated that the PFAAs response to incremental aerobic exercise is associated with the type of training-related metabolic adaptation. A greater turnover and availability of circulating PFAAs for skeletal muscles and other body tissues is observed in endurance- than in sprint-trained individuals. Non-proteinogenic PFAAs, despite low concentrations, also respond to exercise loads, indicating their important, though less understood role in exercise metabolism. Our study provides additional insight into the exercise-induced physiological response of PFAAs, and may also provide a rationale in discussions regarding dietary amino acid requirements in high-performance athletes with respect to sports specialization. [ABSTRACT FROM AUTHOR]

Background: Studies examining post-race emotional experiences in the context of endurance races among recreational athletes are scarce. The purpose of this study was to describe how recreational athletes experience the time after completing an endurance race. Methods: In this study, a qualitative study design was used, and data collection was carried out with semi-structured interviews. The selection of subjects was completed systematically through criterion selection. The selection criteria were men and women, aged 18 years or older, who had completed an endurance race, and finished, lasting at least 180 min within the past 12 months. The interviews were analyzed using conventional qualitative content analysis. Results: Sixteen recreational endurance athletes who, within six months, had completed an endurance race of running, cycling, cross-country skiing or Ironman, participated and were interviewed. Four overarching themes emerged from the analysis: "High on life", "Loss of energy, Ambivalence and Melancholy", "Activity-charged emotions", and "Dimensions of emotions over time and new goals", describing the content of the interviews. Conclusions: Endurance athletes experienced varied post-race emotions that were both physically and mentally challenging, suggesting a holistic approach to managing post-race emotions would be beneficial. From the athletes' perspectives, post-race feelings were dependent on many factors, including time spent training for a specific race, and perceived inability to set new goals for an upcoming training period. Setting future goals prior to an event may be a tool for reducing the risk of negative post-race emotions, including post-race blues. [ABSTRACT FROM AUTHOR]

Background/Objectives: A high level of specific metabolic capacity is essential for maximal sprinting in both male and female athletes. Various factors dictate sex differences in maximal power production and energy utilization. This study aims to compare the contribution of energy systems between male and female athletes with similar sport-specific physiological adaptations during a 15-s sprint exercise. Methods: The endurance group consisted of 17 males (23 ± 7 y) and 17 females (20 ± 2 y). The speed-power group included 14 males (21.1 ± 2.6 y) and 14 females (20 ± 3 y). The contribution of phosphagen, glycolytic, and aerobic systems was determined using the three-component PCr-LA-O2 method. Results: Significant differences were observed in the energy expenditure for all systems and total energy expenditure between males and females in both groups (p = 0.001–0.013). The energy expenditure in kJ for individual systems (phosphagen–glycolytic–aerobic) was 35:25:7 vs. 20:16:5 in endurance males vs. female athletes, respectively. In the speed-power group, male athletes expended 33:37:6 kJ and female athletes expended 21:25:4 kJ, respectively. The percentage proportions did not differ between males and females in any system. The contribution of the phosphagen–glycolytic–aerobic systems was 52:37:11 vs. 48:39:13 in endurance male and female athletes, respectively. For speed-power males vs. female athletes, the proportions were 42:50:8 vs. 41:50:9, respectively. Conclusions: Despite the differences in body composition, mechanical output, and absolute energy expenditure, the energy system contribution appears to have a similar metabolic effect between male and female athletes engaged in sprint exercises with similar sport-related adaptations. The magnitude and profile of sex differences are related to sports discipline. [ABSTRACT FROM AUTHOR]

Mountain running, distinct from traditional road running, involves natural trails with significant elevation changes. This study aims to analyze dietary and supplementation practices among advanced and elite Polish mountain runners. Conducted from May to October 2023, this study included 36 participants (13 women, 23 men) aged 21–43 years. A custom questionnaire assessed nutrition two days before and during a competition, focusing on macronutrient intake, hydration, and supplementation. Statistical analyses were performed to compare advanced and elite athletes. Participants consumed an average of 3164.14 kcal two days before and 3176.97 kcal the day before the competition. Carbohydrate intake averaged 7.69 g/kg two days before and 7.64 g/kg the day before the race, potentially insufficient for optimal glycogen stores. Protein intake was adequate, averaging 1.63 g/kg two days before and 1.73 g/kg the day before the race. Fluid intake averaged 2811.25 mL two days before and 2891.80 mL the day before the race. During races, carbohydrate intake averaged 58.56 g/h, with variations based on race duration. Most participants used isotonic drinks and water for hydration. Mountain runners generally adhere to proper nutrition guidelines, with adequate protein and fluid intake. However, their carbohydrate intake may be insufficient for longer races. Higher carbohydrate intake during exercise could provide additional benefits. [ABSTRACT FROM AUTHOR]

Purpose: To compare acute physiological responses and perceived training stress between one long and two short time- and intensity-matched sessions of moderate-intensity training in endurance athletes. Methods: Fourteen male endurance athletes (VO2max: 69.2 ± 4.2 mL·min-1·kg-1) performed one 6 × 10-min interval session (SINGLE) and two 3 × 10-min interval sessions interspersed with 6.5 h recovery (DOUBLE) of moderate-intensity training on two separate days, while running in the laboratory, using a counterbalanced cross-over trial. The two training days were separated into a first part/session (interval stage 1-3) and second part/session (interval stage 4-6). Respiratory variables, heart rate (HR), blood lactate concentrations (BLa), and rating of perceived exertion (RPE) were collected during sessions, whereas supine heart rate (HR) was assessed in a 60-min recovery period following sessions. Measures of perceived training stress (1-10) were assessed in the morning of the subsequent day. Results: HR, Bla, and RPE increased in the second compared to first part of SINGLE (168 ± 7 vs. 173 ± 7 bpm, 2.60 ± 0.75 vs. 3.01 ± 0.81 mmol·L-1, and 13.4 ± 1.0 vs. 14.8 ± 1.1-point, respectively, all p < 0.05). HR and Bla decreased in the second compared to first session of DOUBLE (171 ± 9 vs. 166 ± 9 bpm and 2.72 ± 0.96 vs. 2.14 ± 0.65 mmol·L-1, respectively, both p < 0.05). SINGLE revealed higher supine HR in the recovery period following sessions (65.4 ± 2.5 vs. 60.7 ± 2.5 bpm p < 0.05), session RPE (sRPE, 7.0 ± 1.0 vs. 6.0 ± 1.3-point, p = .001) and sRPE training load (929 ± 112 vs. 743 ± 98, p < 0.001) compared to DOUBLE. In the subsequent morning, increased levels of perceived fatigue and muscle soreness were observed following SINGLE compared to DOUBLE (7.0 ± 2.5 vs. 8.0 ± 1.0-point, p = .049 and 6.0 ± 2.5 vs. 7.0 ± 2.5-point, p = .002, respectively). Conclusion: One long moderate-intensity training session was associated with a duration-dependent "drift" in physiological responses compared to two short time- and intensity-matched sessions, thereby suggesting a higher overall training stimulus. Simultaneously, the lower cost of the two shorter sessions indicates that such organization could allow more accumulated time at this intensity. Overall, these findings serve as a starting point to better understand the pros and cons of organizing moderate-intensity training as one long versus shorter sessions performed more frequently (e.g., as "double threshold training") in endurance athletes. [ABSTRACT FROM AUTHOR]

Background: Exercise is associated with several cardiac adaptations that can enhance one's cardiac output and allow one to sustain a higher level of oxygen demand for prolonged periods. However, adverse cardiac remodelling, such as myocardial fibrosis, has been identified in athletes engaging in long-term endurance exercise. Cardiac magnetic resonance (CMR) imaging is considered the noninvasive gold standard for its detection and quantification. This review seeks to highlight factors that contribute to the development of myocardial fibrosis in athletes and provide insights into the assessment and interpretation of myocardial fibrosis in athletes. Methods: A literature search was performed using the PubMed/Medline database and Google Scholar for publications that assessed myocardial fibrosis in athletes using CMR. Results: A total of 21 studies involving 1642 endurance athletes were included in the analysis, and myocardial fibrosis was found in 378 of 1595 athletes. A higher prevalence was seen in athletes with cardiac remodelling compared to control subjects (23.7 vs. 3.3%, p < 0.001). Similarly, we found that young endurance athletes had a significantly higher prevalence than veteran athletes (27.7 vs. 19.9%, p < 0.001), while male and female athletes were similar (19.7 vs. 16.4%, p = 0.207). Major myocardial fibrosis (nonischaemic and ischaemic patterns) was predominately observed in veteran athletes, particularly in males and infrequently in young athletes. The right ventricular insertion point was the most common fibrosis location, occurring in the majority of female (96%) and young athletes (84%). Myocardial native T1 values were significantly lower in athletes at 1.5 T (p < 0.001) and 3 T (p = 0.004), although they had similar extracellular volume values to those of control groups. Conclusions: The development of myocardial fibrosis in athletes appears to be a multifactorial process, with genetics, hormones, the exercise dose, and an adverse cardiovascular risk profile playing key roles. Major myocardial fibrosis is not a benign finding and warrants a comprehensive evaluation and follow-up regarding potential cardiac disease. [ABSTRACT FROM AUTHOR]

Objective: To systematically evaluate and meta-analyze the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on athletes of aerobic endurance performance parameters. Methods: PubMed, Web of Science, EBSCO, Embase, and Cochrane databases were searched. The assessment of quality was conducted employing The Cochrane Risk of Bias Assessment Tool, while heterogeneity examination and subgroup analysis were performed. Moreover, regression and sensitivity analyses were executed. Results: There was no significant difference between the effects of HIIT and MICT on the enhancement of athletes' running economy (RE) (P > 0.05); 1–3 weeks and 4–9 weeks of HIIT were more effective in improving athletes' maximum oxygen uptake (VO2max) (P < 0.05), and 10 weeks and above were not significant (P > 0.05); 1–3 weeks of HIIT was more effective in improving athletes' anaerobic threshold (AT) (P < 0.05), and 4–10 weeks was not significant (P > 0.05); 3 weeks of high-intensity interval training (HIIT) did not significantly enhance athletes' minute ventilation (VE) (P > 0.05), whereas a duration of 6–10 weeks yielded superior results (P < 0.05); 8 weeks of moderate-intensity continuous training (MICT) did not significantly enhance athletes' hemoglobin (Hb) level (P > 0.05), whereas a duration of 2–3 weeks yielded superior results (P < 0.05). Conclusions: (1) HIIT and MICT have similar effects on enhancing athletes' RE. (2) 6–9 weeks' HIIT was more effective in improving athletes' VO2max and VE, and 3 weeks' HIIT was more effective in improving athletes' AT. (3) Within 3 weeks, MICT was more effective in improving the Hb level of athletes. Registration number on PROSPERO: CRD42024499039. [ABSTRACT FROM AUTHOR]

Purpose: The linear encoder and the Calf Raise App have been shown to be valid for measurements of plantar flexor muscular endurance in the heel raise test when compared with gold standard equipment. However, the validity of the Calf Raise App has not yet been compared with a linear encoder, an instrument commonly used in clinical and research settings. The purpose of this study was to determine the concurrent validity of the Calf Raise App compared with a linear encoder for the measurement of average heel raise height and total concentric work in the heel raise test. Methods: Fifty TeamGym athletes (82% females) from an on‐going prospective study were included (mean [SD] age: 20 [7] years; body mass index (BMI) = 21.3 [2.5]). Concurrent validity was analysed with single measures intraclass correlation coefficient (ICC) using a two‐way mixed effects, consistency model. Results: Ninety‐eight samples were included in the analysis. The mean (SD) average heel raise height and total concentric work measured by the linear encoder and Calf Raise App were 9.9 (1.4) and 7.5 (1.2) cm, and 1728 (584) and 1291 (450) J, respectively. The mean (SD) number of unilateral heel raises was 30 (7.5). The results showed poor to moderate concurrent validity for the measurement of average heel raise height (ICC: 0.62; 95% confidence interval [CI]: 0.48–0.73). Good to excellent concurrent validity was shown for the measurement of total concentric work (ICC: 0.89; 95% CI: 0.84–0.93). Conclusion: The Calf Raise App shows good concurrent validity in the heel raise test compared with a linear encoder in measuring total concentric work but not average height. While caution is recommended when comparing results from the different instruments, each instrument can be used separately to compare between‐limb differences or changes over time in plantar flexor muscular endurance in clinical and research settings. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

The present study evaluates the effects of pre-race sleep and training characteristics among ultra-athletes and support crew, and the influence of these factors on the athlete's performance in a 217-km ultramarathon. A total of 38 ultramarathon runners and 59 support crew members were assessed. The participants answered questionnaires about chronotype, sleep quality, sleepiness, basic demographics, and pre-race training. The clinical trial registration number is RBR-7j6d23v. The results showed that athletes and support crew had a morning-type chronotype and good sleep efficiency; most had poor-quality sleep. The athletes who finished the race had a higher sleep latency than non-finishers (p < 0.001). The quality of sleep may have impacted performance because the athletes with good sleep quality trained one day more per week than those without (p < 0.001), and training frequency was highly correlated with the race time (r = −0.59). These findings are novel, expand the data about sleep, training, and performance in an ultramarathon, and innovate by addressing the support crew. • Athletes and support crew showed a morning type chronotype and a poor sleep quality, although with good sleep efficiency. • Athletes who finished the race presented a higher sleep latency in training period. • The sleep quality seems to indirectly influence the ultramarathon performance. • Athletes with good sleep train once more per week and the training frequency was correlated with the race time. • The study is innovative to address the impact of habitual sleep on ultramarathon performance and to include support crew. [ABSTRACT FROM AUTHOR]

Maximal oxygen uptake (VO2max) is a determining indicator for cardiorespiratory capacity in endurance athletes, and epigenetics is crucial in its levels and variability. This initial study examined a broad plasma miRNA profile of twenty-three trained elite endurance athletes with similar training volumes but different VO2max in response to an acute maximal graded endurance test. Six were clustered as higher/lower levels based on their VO2max (75.4 ± 0.9 and 60.1 ± 5.0 mL.kg−1.min−1). Plasma was obtained from athletes before and after the test and 15 ng of total RNA was extracted and detected using an SYBR-based 1113 miRNA RT-qPCR panel. A total of 51 miRNAs were differentially expressed among group comparisons. Relative amounts of miRNA showed a clustering behavior among groups regarding distinct performance/time points. Significantly expressed miRNAs were used to perform functional bioinformatic analysis (DIANA tools). Fatty acid metabolism pathways were strongly targeted for the significantly different miRNAs in all performance groups and time points (p < 0.001). Although this pathway does not solely determine endurance performance, their significant contribution is certainly achieved through the involvement of miRNAs. A highly genetically dependent gold standard variable for performance evaluation in a homogeneous group of elite athletes allowed genetic/epigenetic aspects related to fatty acid pathways to emerge. [ABSTRACT FROM AUTHOR]

Background: Long-term adaptations and ongoing training seem to modify the energy system contribution in highly trained individuals. We aimed to compare the energy metabolism profile during sprint exercise in athletes of different specialties. Methods: Endurance (n = 17, 20.3 ± 6.0 yrs), speed-power (n = 14, 20.3 ± 2.5 yrs), and mixed (n = 19, 23.4 ± 4.8 yrs) athletes performed adapted 15-second all-out test before and after a general preparation training period. The contribution of phosphagen, glycolytic, and aerobic systems was calculated using the three-component PCr-LA-O2 method. Results: Between-group differences were observed in the contribution of energy systems in the first and second examinations. The proportions were 47:41:12 in endurance, 35:57:8 in team sports, and 45:48:7 in speed-power athletes. Endurance athletes differed in the phosphagen (p < 0.001) and glycolytic systems (p = 0.006) from team sports and in the aerobic system from speed-power athletes (p = 0.003). No substantial shifts were observed after the general preparatory phase, except a decrease in aerobic energy contribution in team sports athletes (p = 0.048). Conclusion: Sports specialization and metabolic profile influence energy system contribution during sprint exercise. Highly trained athletes show a stable energy profile during the general preparation phase, indicative of long-term adaptation, rather than immediate training effects. [ABSTRACT FROM AUTHOR]

Athletes use hypoxic living and training to increase hemoglobin mass (Hbmass), but Hbmass declines rapidly upon return to sea level. We investigated whether intermittent hypoxic exposure (IHE) + continuous hypoxic training (CHT) after return to sea level maintained elevated Hbmass, and if changes in Hbmass were transferred to changes in maximal oxygen uptake (V̇ o 2max) and exercise performance. Hbmass was measured in 58 endurance athletes before (PRE), after (POST1), and 30 days after (POST2) a 27 ± 4-day training camp in hypoxia (n = 44, HYP) or at sea level (n = 14, SL). After returning to sea level, 22 athletes included IHE (2 h rest) + CHT (1 h training) in their training every third day for 1 mo (HYPIHE + CHT), whereas the other 22 HYP athletes were not exposed to IHE or CHT (HYPSL). Hbmass increased from PRE to POST1 in both HYPIHE + CHT (4.4 ± 0.7%, means ± SE) and HYPSL (4.1 ± 0.6%) (both P < 0.001). Compared with PRE, Hbmass at POST2 remained 4.2 ± 0.8% higher in HYPIHE + CHT (P < 0.001) and 1.9 ± 0.5% higher in HYPSL (P = 0.023), indicating a significant difference between the groups (P = 0.002). In SL, no significant changes were observed in Hbmass with mean alterations between −0.5% and 0.4%. V̇ o 2max and time to exhaustion during an incremental treadmill test (n = 35) were elevated from PRE to POST2 only in HYPIHE + CHT (5.8 ± 1.2% and 5.4 ± 1.4%, respectively, both P < 0.001). IHE + CHT possesses the potential to mitigate the typical decline in Hbmass commonly observed during the initial weeks after return to sea level. NEW & NOTEWORTHY: Sets of 2-h intermittent hypoxic exposure + 1-h continuous hypoxic training, every third day, possess the potential to mitigate the typical decline in Hbmass that is commonly observed during the initial weeks after return to sea level from an altitude camp. Inclusion of IHE + CHT in the training regimen was also accompanied by improvements in V̇ o 2max and exercise performance in most but not all Tier 3–Tier 5 level endurance athletes during the training season. [ABSTRACT FROM AUTHOR]

For athletes, iron plays an important role in improving oxygen supply, energy production, muscle function, and cognitive performance. However, iron deficiency is a common problem in athletes, especially endurance athletes, due to factors such as increased iron loss due to exercise-induced sweating, hematuria, and gastrointestinal bleeding. Exercise induces hematological adaptations due to increased demand of oxygen transport as well as inflammation, which reduces the ability to absorb iron post-exercise. Iron deficiency can lead to fatigue, reduced performance, poorer recovery and increased susceptibility to infections. Iron absorption is tightly regulated to prevent toxicity, with hepcidin playing a central role. Elevated hepcidin levels, which are influenced by exercise-induced inflammation and circadian rhythms, can significantly reduce iron absorption. In addition, the bioavailability of dietary iron varies, with heme iron from animal products being more readily absorbed than non-heme iron from plant sources. Athletes on a vegetarian or vegan diet may require increased iron intake to meet their needs. Monitoring iron status through regular blood tests, including serum ferritin and hemoglobin levels, is critical for early detection and treatment of iron deficiency. Strategies to improve iron absorption include consuming iron-rich foods with promoters such as vitamin C, while inhibitors such as phytates and calcium should be avoided. In cases of significant deficiency, supplementation under medical supervision may be necessary. Understanding these factors and using appropriate nutritional and monitoring practices can help athletes maintain optimal iron levels and overall performance. [ABSTRACT FROM AUTHOR]

Highlights Insertions and deletions (indels) are the second most common type of variation in the human genome. However, limited data on their associations with exercise‐related phenotypes have been documented. The aim of the present study was to examine the association between 18,370 indel variants and power athlete status, followed by additional studies in 357,246 individuals. In the discovery phase, the D allele of the MDM4 gene rs35493922 I/D polymorphism was over‐represented in power athletes compared with control subjects (P = 7.8 × 10−9) and endurance athletes (P = 0.0012). These findings were replicated in independent cohorts, showing a higher D allele frequency in power athletes compared with control subjects (P = 0.016) and endurance athletes (P = 0.031). Furthermore, the D allele was positively associated (P = 0.0013) with greater fat‐free mass in the UK Biobank. MDM4 encodes a protein that inhibits the activity of p53, which induces muscle fibre atrophy. Accordingly, we found that MDM4 expression was significantly higher in the vastus lateralis of power athletes compared with endurance athletes (P = 0.0009) and was positively correlated with the percentage of fast‐twitch muscle fibres (P = 0.0062) and the relative area occupied by fast‐twitch muscle fibres (P = 0.0086). The association between MDM4 gene expression and an increased proportion of fast‐twitch muscle fibres was confirmed in two additional cohorts. Finally, we found that the MDM4 DD genotype was associated with increased MDM4 gene expression in vastus lateralis and greater cross‐sectional area of fast‐twitch muscle fibres. In conclusion, MDM4 is suggested to be a potential regulator of muscle fibre specification and size, with its indel variant being associated with power athlete status. What is the central question of this study? Which indel variants are functional and associated with sport‐ and exercise‐related traits? What is the main finding and its importance? Out of 18,370 tested indels, the MDM4 gene rs35493922 I/D polymorphism was found to be the functional variant (affecting gene expression) and the most significant, with the deletion allele showing associations with power athlete status, fat‐free mass and cross‐sectional area of fast‐twitch muscle fibres. Furthermore, the expression of MDM4 was positively correlated with the percentage of fast‐twitch muscle fibres and the relative area occupied by fast‐twitch muscle fibres. What is the central question of this study?Which indel variants are functional and associated with sport‐ and exercise‐related traits?What is the main finding and its importance?Out of 18,370 tested indels, the MDM4 gene rs35493922 I/D polymorphism was found to be the functional variant (affecting gene expression) and the most significant, with the deletion allele showing associations with power athlete status, fat‐free mass and cross‐sectional area of fast‐twitch muscle fibres. Furthermore, the expression of MDM4 was positively correlated with the percentage of fast‐twitch muscle fibres and the relative area occupied by fast‐twitch muscle fibres. [ABSTRACT FROM AUTHOR]

This study delves into the intricate details of Mixed Martial Arts (MMA) by examining key variables such as maximal oxygen uptake (VO2 peak), aerobic energy (EAER), anaerobic energy (EAN), and accumulated O2 deficit (DOA). By investigating associations and comparing athletes in the −61 kg bantamweight and −66 kg featherweight weight divisions, we aim to shed light on their physiological characteristics. The sample consisted of 20 male volunteers separated into two paired groups: ten athletes in the category up to 61 kg (age: 27.7 ± 5.9 years old, height: 170.9 ± 3.4 cm, body mass: 72.8 ± 1.4 kg, fat percentage: 9.5% ± 3.0%, professional experience: 7.5 ± 7.1 years) and ten athletes up to 66 kg (age: 27.6 ± 2.9 years old, height: 176.0 ± 5.5 cm, body mass: 77.0 ± 1.5 kg, fat percentage: 7.85% ± 0.3%, professional experience: 5.5 ± 1.5 years). Remarkably, our findings revealed striking similarities between the two weight divisions. Furthermore, we discovered a negative correlation between VO2 peak and the number of MMA fights, indicating a potential impact of professional experience on aerobic capacity (r = −0.65, p < 0.01). Additionally, the number of fights exhibited negative correlations with anaerobic energy (r =−0.53, p < 0.05) and total energy cost (r =−0.54, p < 0.05). These results provide valuable insights for designing training programs in the context of MMA. While training both weight divisions together can be beneficial, it is equally crucial to incorporate specific weight-class-focused training to address each division’s unique physical demands and requirements. [ABSTRACT FROM AUTHOR]

Highlights The aim of this retrospective analysis was to provide a more comprehensive understanding of the cardiorespiratory profile of world‐class ILCA‐7 sailors (n = 3, all males), through a longitudinal evaluation offering real‐world data on physiological profile and exercise intensity domains. The cardiopulmonary exercise testing (CPET) was performed by the same researchers using the same equipment during the study. Assessments took place twice a year, aligning with major international competition preparations. Participants trained and competed at the same sailing club in Split, Croatia, under consistent supervision from the same team throughout the study, winning a total of 21 medals at major international competitions. The recorded V̇O2peak${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ ranged from 51.7 ± 1.6 to 61.9 ± 3.0 mL min−1 kg−1, respectively. Similarly, peak power output varied from 352 ± 10 to 426 ± 34 W. The changes in physiological responses at the ventilatory thresholds were proportional to the changes in peak cardiorespiratory fitness capacity. Interestingly, the oxygen pulse measured in 2015 was 25 ± 1 mL O2 beat−1. Over the subsequent 6 years, the O2 pulse marginally increased and appeared to stabilize at 27 ± 1 mL O2 beat−1 in 2020, when these athletes were 32 ± 3 years old. This work offers a broader understanding of world‐class Olympic sailors’ cardiorespiratory fitness, going beyond the standard assessment of peak V̇O2${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ to incorporate an analysis of ventilatory thresholds. While a direct link between cardiorespiratory fitness and competitive success remains ambiguous, the importance of a well‐rounded aerobic capacity for excellence in ILCA‐7 sailing class is evident. What is the central question of this study? What are the temporal changes in the physiological profiles of three world‐class ILCA‐7 sailors? What is the main finding and its importance? Data on oxygen pulse adjustments suggest the involvement of compensatory cardiovascular mechanisms, likely associated with the isometric and quasi‐isometric contractions inherent in ILCA‐7 sailing. This is evidenced by the absence of an age‐related increase in oxygen pulse, a phenomenon often observed in endurance athletes throughout their competitive careers. What is the central question of this study?What are the temporal changes in the physiological profiles of three world‐class ILCA‐7 sailors?What is the main finding and its importance?Data on oxygen pulse adjustments suggest the involvement of compensatory cardiovascular mechanisms, likely associated with the isometric and quasi‐isometric contractions inherent in ILCA‐7 sailing. This is evidenced by the absence of an age‐related increase in oxygen pulse, a phenomenon often observed in endurance athletes throughout their competitive careers. [ABSTRACT FROM AUTHOR]