Breast cancer is a leading cause of mortality and morbidity among females worldwide. As part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2023, we provided an updated comprehensive assessment of the epidemiological trends, disease burden, and risk factors associated with breast cancer globally, regionally, and nationally from 1990 to 2023. Breast cancer incidence, mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs) were estimated by age and sex for 204 countries and territories from 1990 to 2023. Mortality estimates were generated using GBD Cause of Death Ensemble models, leveraging data from population-based cancer registration systems, vital registration systems, and verbal autopsies. Mortality-to-incidence ratios were calculated to derive both mortality and incidence estimates. Prevalence was calculated by combining incidence and modelled survival estimates. YLLs were established by multiplying age-specific deaths with the GBD standard life expectancy at the age of death. YLDs were estimated by applying disability weights to prevalence estimates. The sum of YLLs and YLDs equalled the number of DALYs. Breast cancer burden attributable to seven risk factors was examined through the comparative risk assessment framework. The GBD forecasting framework was used to forecast breast cancer incidence and mortality from 2024 to 2050. Age-standardised rates were calculated for each metric using the GBD 2023 world standard population. In 2023, there were an estimated 2·30 million (95% uncertainty interval [UI] 2·01 to 2·61) breast cancer incident cases, 764 000 deaths (672 000 to 854 000), and 24·1 million (21·3 to 27·5) DALYs among females globally. In the World Bank low-income group, where a low age-standardised incidence rate (ASIR) was estimated (44·2 per 100 000 person-years [31·2 to 58·4]), the age-standardised mortality rate (ASMR) was the highest (24·1 per 100 000 [16·8 to 31·9]). The highest ASIR was in the high-income group (75·7 per 100 000 [67·1 to 84·0]), and the lowest ASMR was in the upper-middle-income group (11·2 per 100 000 [10·2 to 12·3]). Between 1990 and 2023, the ASIR in the low-income group increased by 147·2% (38·1 to 271·7), compared with a 1·2% (-11·5 to 17·2) change in the high-income group. The ASMR decreased in the high-income group, changing by -29·9% (-33·6 to -25·9), but increased by 99·3% (12·5 to 202·9) in the low-income group. The increase in age-standardised DALY rates followed that of ASMRs. Risk factors such as dietary risks, tobacco use, and high fasting plasma glucose contributed to 28·3% (16·6 to 38·9) of breast cancer DALYs in 2023. The risk factors with a decrease in attributable DALYs between 1990 and 2023 were high alcohol use and tobacco. By 2050, the global incident cases of breast cancer among females were forecast to reach 3·56 million (2·29 to 4·83), with 1·37 million (0·841 to 2·02) deaths. The stable incidence and declining mortality rates of female breast cancer in high-income nations reflect success in screening, diagnosis, and treatment. In contrast, the concurrent rise in incidence and mortality in other regions signals health system deficits. Without effective interventions, many countries will fall short of the WHO Global Breast Cancer Initiative's ambitious target of achieving an annual reduction of 2·5% in age-standardised mortality rates by 2040. The mounting breast cancer burden, disproportionately affecting some of the world's most vulnerable populations, will further exacerbate health inequalities across the globe without decisive immediate action. Gates Foundation, St Jude Children's Research Hospital.
The objectives were to (a) establish normative grip strength values in young tennis players; (b) examine developmental changes across 4 adolescent age groups and sexes, controlling for maturity and body size; (c) assess the association between body size and grip strength independent of age and maturity; (d) evaluate grip strength's ability to distinguish successful from less-successful players, independent of age, maturity, and body size; and (e) compare dominant and nondominant hands to identify tennis-related lateral differences. Two hundred and fourteen competitive tennis players (ages 9-18; both sexes) underwent standardized assessment of dominant- and nondominant handgrip strength with a dynamometer. Body mass and height were measured with a medical scale and stadiometer. Age, sex, and competitive level were recorded, and maturity status was estimated. Associations and group differences were analyzed using analysis of covariance and multiple regression. Body mass was the only independent predictor of grip strength in both hands (P < .01), explaining 67% to 80% of the variance after adjusting for age and maturity status. Height was not significant once covariates were controlled. No differences in grip strength were observed between high- and low-achieving players after adjustment. Across the entire sample, dominant handgrip strength was greater than nondominant hand strength (P < .001). In youth tennis players, handgrip strength is strongly related to overall body mass but not to competitive success when age and maturation are taken into account. Dominant-hand superiority is a consistent, sport-specific adaptation. The normative values presented can guide monitoring and training of developing tennis athletes.
This study examined the associations between laboratory-based performance indicators and competitive success in elite cross-country skiing, considering sex- and age-related differences over a 15-year period. A total of 106 Swiss National Team cross-country skiers (62 males and 44 females) underwent standardized physiological testing including 24-minute double-poling treadmill time-trial performance (24-minute DP), maximal oxygen uptake (V˙O2max), performance at the second lactate threshold, hemoglobin mass, 1-minute skating treadmill time-trial performance (Sprint1-min), squat jump peak power, and fat-free mass. Competitive performance was assessed using International Ski Federation (FIS) points in distance (FISDist) and sprint (FISSpr) events. Mixed-effects models analyzed the predictive strength of test variables, incorporating sex and age interactions. Twenty-four-minute DP and relative V˙O2max explained 42% of the variance in FISDist, while Sprint1-min (66%), squat jump, and absolute V˙O2max (both 50%) were the strongest predictors of FISSpr. Improvements in 24-minute DP, second lactate threshold, and Sprint1-min had a greater impact on reducing FIS points in females, whereas relative and absolute V˙O2max, hemoglobin mass, squat jump, and fat-free mass showed similar predictive relationships across sexes. Age moderated these associations, with younger athletes experiencing greater reductions in FIS points per unit increase in test performance. This study highlights the importance of a comprehensive performance assessment in elite cross-country skiing that integrates ski-specific time trials, physiological capacity, strength, and body composition. The findings indicate that the relevance of laboratory-based performance indicators varies by sex and career stage, underscoring the need for longitudinal, age-aware interpretation when relating test outcomes to on-snow performance.
The aim of this study was to (1) explore differences in countermovement jump (CMJ) force-time metrics between stronger and weaker female handball and basketball players, (2) examine relationships between isometric midthigh pull (IMTP) peak force and CMJ metrics, and (3) produce reference values for CMJ and IMTP metrics. A cross-sectional design was used with 125 competitive female players (74 handball and 51 basketball). Each player performed 2 trials of IMTP and 3 of CMJ using force plates. Based on IMTP relative net peak force, players were split into stronger (n = 62) and weaker (n = 63) groups using a median split analysis. Differences between groups were analyzed with independent t tests and Hedge g effect sizes, and Pearson correlations were calculated to assess associations between IMTP peak force and CMJ force-time metrics for stronger and weaker players separately. Stronger players demonstrated large and moderate differences in jump height (0.30 [0.04] vs 0.26 [0.04] m; P < .001; effect size = 0.95, large) and modified reactive strength index (0.47 [0.09] vs 0.41 [0.08] a.u.; P < .001; effect size = 0.67, moderate), respectively. Moreover, moderate to strong correlations were found between IMTP peak force and CMJ propulsive net impulse and braking net impulse (r = .495-.647, P < .001). These results highlight the association between maximal isometric strength and vertical jump performance in handball and basketball players. Strength and conditioning coaches may design and implement training programs that focus on developing and preserving maximal strength throughout the season to potentially support jump performance.
This study aimed to examine effects of game load metrics, technical-tactical approaches, and contextual factors on game performance indicators in male professional basketball players. Data were collected across 26 official games from a single basketball team competing in a professional men's basketball competition. Game load metrics (rating of perceived exertion, PlayerLoad, accelerations, decelerations, jumps, and changes-of-direction); technical-tactical approaches (closeness, betweenness, and eigenvector centrality); and contextual factors (score differential and opponent level) were inputted into separate linear mixed-effects models to evaluate their relationships with 6 different game performance indicators including score, performance index rating, player total contribution, player impact estimate, game score, and efficiency (EFF). Regarding load metrics, rating of perceived exertion was positively associated with all performance indicators (β = 0.449-0.697, P < .001), while high-intensity jumps were positively associated with player total contribution (β = 0.184, P = .003), player impact estimate (β = 0.322, P = .002), performance index rating (β = 0.241, P < .001), and EFF (β = 0.150, P = .007). For technical-tactical approaches, closeness centrality was positively associated with EFF (β = 0.411, P = .012). For contextual factors, greater score differential was associated with higher player total contribution (β = 0.206, P = .038), player impact estimate (β = 0.416, P = .033), performance index rating (β = 0.262, P = .003), and EFF (β = 0.225, P = .011). Rating of perceived exertion and high-intensity jumping loads may be key factors to prioritize in preparing and monitoring players. Given player performance was influenced by score differential but not opponent level, players were able to sustain consistent performance outputs regardless of opponent strength.
Interest in menstrual health and sports performance has increased, with the majority of research focusing on females with a eumenorrheic menstrual cycle. This invited commentary discusses the need to broaden our approach when conducting menstrual health-related research in physically active and athletic populations. We highlight the current state of research regarding the effect of menstrual cycle phase on performance-determining variables, acute training responses, recovery measures, and performance, and question the benefit of continuing to conduct studies that focus only on the most hormonally distinct eumenorrheic menstrual cycle phases. The high prevalence of menstrual disturbances and hormonal contraceptive use, in addition to the challenges and/or possible impracticality of using gold-standard methods of tracking menstrual cycles, regrettably limits the generalizability of findings. Therefore, we identify several knowledge gaps and propose methodological approaches that may improve our understanding of menstrual health in female athletes and the circumstances under which they train and perform. By broadening our research approach, rather than focusing primarily on eumenorrheic cycles, we can provide female athletes and their support teams with more practically applicable evidence-based information to promote health and performance.
The tethered swimming test is relevant for the longitudinal monitoring of swimmers. However, for accurate interpretation of observed variations over time, understanding the reliability of the test and the factors influencing it is crucial. This study aimed to assess the absolute and relative reliability of parameters derived from 10- and 30-second front-crawl-tethered swimming tests by considering swimming specialty, sex, and performance level. Output variables resulting from manual stroke cycle segmentation were examined to evaluate interevaluator reliability. Twenty-one highly trained swimmers performed the 2 specific time-based tests over 3 consecutive days. Relative and absolute reliability were assessed using the intraclass correlation coefficient and standard error of measurement, respectively. Mean force, peak force, and impulse demonstrated high reliability (intraclass correlation coefficient > .86 and .73 for 10- and 30-s tests, respectively). Fatigue index, performance decrement, and rate of performance decline exhibited varying reliability from poor to high. These results were unaffected by swimming specialty, sex, performance level, or evaluator. The findings indicate that 10- and 30-second front-crawl tethered swimming tests are highly reliable. Mean force, peak force, and impulse emerge as the most reliable parameters, regardless of the swimming specialty, sex, performance level, or evaluator.
The purpose of the study was to jointly estimate the effects of body mass and age on the total of the sum of snatch and clean & jerk in weightlifting and to examine sex- and age-related performance decline in male and female Masters weightlifters. Generalized additive models for location, scale, and shape were used to estimate the distribution of the weightlifting total, based on world championships of Masters athletes 2018-2025 and checked for robustness during 2000-2025. The model ranks weightlifting performances on the same scale for both sexes across body mass and age. Among 4939 Masters weightlifting results (ages 35-92), a higher total correlated with a higher body mass, but this effect weakened with age (P < .001). Body mass (mean = 85.6 kg for males, 67.7 kg for females) had a 1.5 times larger impact on the total in males. The decline with age was steeper for females between ages 45 and 55 but otherwise similar to males. Scaled performances over 25 years (12,060 results) were stable over time in males but rose to a plateau from 2018 in females. Weightlifting performances based on the total can be ranked on the same scale for male and female Masters athletes. This method can be incorporated in competitions for mixed teams. It aids athletes, coaches, and health professionals in monitoring progress over time relative to the performance of age and body mass groups.
Elite athlete support can involve substantial testing and monitoring data. A practical and meaningful framework can help practitioners optimize service delivery. We present the concepts of performance determinants and moderating factors and emphasize prioritization of macroscopic (visually observable) measures for effective application in sports where direct athlete interaction is minimal. We advocate that performance determinants are measures that must be enhanced to improve the targeted outcome, such as 100-m sprint time (example herein). In this case, the determinants comprise relevant sprint-specific measures-acceleration time, maximal velocity, and maintenance, with secondary determinants derived from nonsprinting measures (eg, jumping relative power, reactive strength)-identified in the sports literature and endorsed by the support team. Moderating factors involve measures that must be maintained at an optimal level to positively influence determinant factors and overall performance. Reaction time, early acceleration time, mechanics (technical elements) in different phases, maximal strength, neuromuscular status, and body composition are all relevant factors. For effective implementation, a 3-stage process (CEO - consultation, evaluation, and optimization) is proposed to integrate training/coaching and performance support, with active involvement of coaches, athletes, and staff to ensure clarity, buy-in, and timely individualized adjustments. Other considerations include the structure of team support, work arrangements (eg, integrated support), and support delivery strategies (eg, embedded services), all of which require systematic planning, commitment of key personnel, and regular internal review. This approach enables effective, actionable performance support for elite athletes and coaches. Changes in athlete performance should be interpretable through the identified performance determinants and moderating factors.
To determine the impact of Wavelight Technology on performance and tactical and pacing behavior in 1500-m Diamond League events. A total of forty-five 1500-m Diamond League races held between 2021 and 2024 were categorized as non-Wavelight (n = 12) and Wavelight (n = 33) races. Athletes in each race were grouped by their final ranking: top 4 (T4), fifth to eighth (T8), and ninth to twelfth (T12). The 100-m section data were collected to assess athletes' section speeds, intermediate positions, and number of position changes. Additionally, finishing times and coefficient of variation of pace (CV%) were obtained for each athlete. Finishing times were faster in Wavelight than non-Wavelight races across groups (P < .001; 0.87 ≤ d ≤ 1.74) with lower CV% values in Wavelight races (P < .001; 0.60 ≤ d ≤ 0.86). A U-shaped pacing profile was observed in T4 and T8 groups, although it was less pronounced in Wavelight races (ie, lower speed drop in the middle part, and a reduced endspurt), while T12 groups displayed a positive pacing profile, with a greater speed decrease in non-Wavelight races. There were fewer position changes in Wavelight than non-Wavelight races. Wavelight races were more evenly paced than non-Wavelight races, which likely resulted in lower metabolic disturbances and the superior performance observed in Wavelight versus non-Wavelight races. Optimizing pacing strategies through Wavelight technology may assist coaches and athletes in improving race execution, enhancing performance, and achieving personal bests or qualification standards for international championships.
To investigate contributions of start, turn, and clean-swimming performance on total race time in top-elite junior and adult female swimmers. A total of 681 long-course races from European junior and adult championships (50-1500 m including heats, semifinals, and finals) were video-analyzed. Start, turn, and clean-swimming performances showed a nonlinear development across race distances in both junior and adult swimmers. Start times progressively increased from 50 to 400 m and plateaued at 800 m. Turn times increased and clean-swimming speed decreased from 50 to 200 m and plateaued at 400 m. Clean-swimming speed showed the largest contribution to total race time. Start performance contributed most to sprint races, and the contribution of turn performance resembled an inverted U-shape, with highest contributions to 200- and 400-m races. Adult swimmers showed significantly faster start times over 50- (6.03%) to 200-m races (5.86%). Age-group differences in turn times were significant for 100 (4.92%) and 200 m (6.49%) but gradually declined over longer race distances. Clean-swimming speeds differed most over 50- (3.17%) and 100-m races (1.71%), with consistent but small differences for longer race distances (1.23%-1.34%). Percentile-based reference values were incorporated into a software-based tool that predicts and modulates total race time according to changes in start, turn, and clean-swimming performance. The present findings help coaches identify individual swimmers' strengths and weaknesses and translate performance analysis data into targeted training and race strategies.
This study evaluated the practical feasibility of the CORE sensor for noninvasive tracking of changes in estimated core body temperature (Est-Tcore) during simulated beach volleyball match-play in the heat and examined the effects of a combined cooling strategy on countermovement jump (CMJ) and T-agility performance. Eleven competitive male collegiate players completed 2 simulated match-play trials under hot outdoor conditions using a randomized crossover design. The COOL condition included precooling with an ice vest and ice slurry ingestion, followed by additional ice slurry during breaks. The CON condition replicated fluid intake without cooling. Est-Tcore and heart rate (HR) were continuously monitored, and thermal sensation, thermal comfort, and session-rating of perceived exertion were assessed. CMJ and T-agility performance were measured immediately before and after the matches. COOL attenuated the increase in Est-Tcore during warm-up and improved perceptual responses (lower thermal sensation, P < .05), while HR did not differ significantly between conditions. Postmatch CMJ and T-agility did not differ significantly between the conditions, although small-to-moderate effect sizes suggested a possible preservation of performance. The CORE sensor demonstrated practical applicability for tracking relative changes in Est-Tcore during beach volleyball match play. Combined external-internal cooling attenuated thermal strain and improved perceptual responses; however, these effects did not translate into clear benefits for explosive performance outcomes.
Exercise performance is compromised in hot and humid conditions compared to temperate circumstances. However, it remains unclear which factors predispose individuals to either small or large performance decrements. This study aimed to identify factors associated with performance decrements in elite athletes during exercise under hot and humid ambient conditions. One hundred and six Dutch elite athletes performed a standardized incremental exercise test in a temperate condition (TEMP, ambient temperature 15.9 °C [1.2 °C], and relative humidity 55% [6%]) and hot-humid condition (HOT, ambient temperature 31.6 °C [1.0 °C], and relative humidity 74% [5%]). Performance loss was determined by the relative difference in time to exhaustion between both conditions. Multivariable linear regression analyses were performed to determine the association between performance loss and athlete characteristics, exercise responses, thermoregulatory responses, and perceptual parameters. Time to exhaustion decreased from 60 (14) minutes in TEMP to 44 (10) minutes in HOT, corresponding to an average performance decrement of 26% (11%). Higher dehydration rates and more thermal discomfort in TEMP were associated with greater performance decrements. On the other hand, a higher BMI, female sex, greater exercise-induced increases in core temperature (TC) in HOT, and a higher peak heart rate (HR) and exercise-induced increases in HR in HOT versus TEMP were associated with less performance decrements (adjusted R2 = .58; P < .001). We identified that variables related to exercise responses (ie, HR, dehydration), athlete characteristics (ie, BMI, sex), thermoregulatory responses (ie, TC), and perception (ie, thermal discomfort) were associated with performance decrements during exercise in the heat. Our multivariable regression model explained 58% of the magnitude of performance decrements.
The effects of sexual activity on athletic performance have been debated for centuries, with traditional abstinence beliefs lacking scientific foundation. We sought to map existing literature examining acute and delayed effects of sexual activity on athletic performance, and identify knowledge gaps across mechanistic pathways. Sexual activity encompassed intercourse, masturbation, or orgasm-culminating activities. Performance outcomes included strength, endurance, power, speed, reaction time, and sport-specific skills. This scoping review followed PRISMA-ScR guidelines. Searches covered PubMed/Medline, Scopus, Web of Science, and PsycINFO (inception-July 2025). Population-Concept-Context framework guided study selection. Extracted data covered demographics, performance modalities, timing, and mechanisms. Narrative synthesis addressed heterogeneity. Available evidence indicates sexual activity ≥10 to 12 hours pretesting yields no observed performance impairment. Cardiovascular recovery effects occur with ≤2-hour intervals. One study (n = 16) documented maximal lower-limb strength reduction within 24 hours. Athletes report variable performance expectations (40% perceive immediate negative effects; 90% report no influence at ≥12 h). Studies exhibited small sample sizes (n = 2-16), 99% male representation, and methodological heterogeneity. Proposed acute mechanisms include hormonal fluctuations and minimal energy expenditure (1.8-2.8 metabolic equivalent of tasks). Hypothesized delayed pathways involve sleep quality and stress modulation. Existing studies demonstrate no performance impairment when sexual activity occurs ≥10- to 12-hour precompetition. Sleep quality improvements require further investigation. Psychological expectations and cultural contexts appear influential based on athlete surveys. Critical gaps include female underrepresentation (99% male samples), age diversity (studies limited to 20-40 y), and ethnic homogeneity. Rigorous investigations with diverse populations remain necessary to establish evidence-based practice guidelines.
Sided games are very popular in football (soccer) training, designed to integrate technical, tactical, and physical development through the manipulation of constraints such as player numbers, pitch size, and rules, among other variables. However, inconsistent terminology, methodological heterogeneity, and limited empirical guidance have hindered its methodological advancement across research and practice. This consensus aimed to establish a unified framework and evidence-based recommendations for the design, monitoring, and application of sided games in football, providing conceptual clarity and practical guidance for coaches and sport scientists. A multidisciplinary group of 20 international experts in football science and coaching developed the framework through a 3-stage process: (1) theoretical model development, (2) synthesis of priority areas based on an umbrella review of 12 systematic reviews and meta-analyses, and (3) iterative drafting and blinded consensus voting on statements using a 9-point Likert scale. Seven statements achieved consensus (scores 7-9), defining sided games in soccer, delineating important influencing factors (coach philosophy, environmental, task, and individual constraints), defining monitoring principles, and highlighting benefits and limitations. The consensus confirmed sided games as effective for developing aerobic fitness and tactical-technical behaviors but less effective for strength, power, and high-speed performance adaptations. This consensus provides the first framework for sided game training in football, unifying terminology, and guiding evidence-based design. Its implementation can enhance training coherence, optimize player development, and inform future research addressing existing methodological and population-specific gaps.
Soccer requires repeated changes of direction (COD) and single-leg decelerations (SLD), which accrue considerable mechanical stress on the lower limbs. These actions place significant demands on the players' musculoskeletal system. An uneven utilization of these actions between limbs, arising from disparities in neuromuscular control and skill acquisition, may lead to asymmetries and increased injury risk. This study aimed to examine the effects of player position and footedness on the frequency of intense CODs, SLDs, and the total sum of the 2 actions (TOT) performed by the dominant and nondominant foot in elite male youth soccer players. Twenty-five elite English youth soccer players were grouped by their playing positions (lateral: full-backs and wide midfielders; central: center defenders, center midfielders, and strikers) and footedness (left or right footed). High-intensity CODs and SLDs were identified using video analysis and GPS data across 6 matches. The frequency and distribution of these actions were analyzed to assess the impact of player position and limb dominance. No significant differences were found in the percentage distribution of SLDs or TOT between the central and lateral groups. However, central players exhibited a significantly greater imbalance in COD frequency compared with lateral players (51.8% [31.5%] vs 29.9% [31.1%]; P < .05; d = 0.70). Players performed more CODs in the direction opposite to their dominant limb, indicating a preference for using the dominant limb as the plant limb (4.6 [3.2] vs 3.7 [2.6]; P < .05; d = 0.31). The study highlights the mechanical and positional demands placed on soccer players, with central players showing greater COD frequency asymmetry.
While the development of cardiorespiratory fitness in normally active children and adolescents is well-documented, longitudinal data on physiological adaptations to training in youth athletes remain limited. This study aimed to investigate the long-term development of cardiorespiratory fitness in young competitive athletes over a period of 2-6 years. A total of 397 young athletes (48 girls), aged 8-20 years, from a variety of sports underwent up to 6 repeated assessments between 2012 and 2024. Peak exercise performance (Wmax) and peak aerobic power (VO2peak), both were measured via cardiopulmonary exercise testing on an electronically braked cycle ergometer. A linear mixed model analysis was used to evaluate longitudinal changes in VO2peak and Wmax (both normalized to body mass), including body surface area and training intensity (MET-hours/week) as fixed effects, with sex-stratified analyses. A total of 1009 cardiopulmonary exercise testing were analyzed. At baseline, boys showed higher age-specific VO2peak and Wmax, while girls had higher age-specific VO2peak despite similar training intensity. Longitudinally, VO2peak increased significantly with age in mid-adolescent girls and boys, particularly in endurance athletes, and was positively associated with training intensity. Wmax rose with age but was less influenced by training or sport type, showing a stronger relationship with growth-related factors like body surface area. VO2peak development in youth athletes is influenced by age, body size, training intensity, and sport type, making it a sensitive marker of aerobic adaptation. In contrast, Wmax reflects primarily maturational growth and is less responsive to training-specific factors.
Prior cycling research has primarily investigated lower limb muscle activation, biomechanical power output, and aerodynamic drag, often overlooking upper limb functions, posture-specific fatigue, and applicability to amateurs. This study examines the relationship between aerodynamic drag and upper limb muscle activity to identify optimal cycling postures balancing aerodynamic efficiency and physiological demands. Nine male recreational cyclists participated in 3 sessions: 1 wind tunnel session measuring drag area and 2 sessions assessing surface electromyography (EMG) of 6 upper body muscles-flexor carpi radialis (FCR), biceps brachii (BB), medial triceps brachii (TB), anterior deltoids (AD), upper trapezius (UT) and lumbar erector spinae (ES)-in drops and hoods hand positions across ten forearm angles. Results showed a linear relationship between aerodynamic drag and composite EMG with forearm angle (R2 > 0.9). Lower forearm angles reduced drag but increased muscle activity. Muscle TB dominated muscle activation in both hand positions. More crouched postures increased EMG amplitude in BB and TB in drops (P < .05), and BB, TB, AD, and UT in hoods (P < .05), with reduced median frequency in FCR in drops (P < .05). Reduced drag in aerodynamic postures corresponds linearly to increased upper limb muscle activation, with greater recruitment of FCR, BB, and AD in drops, and of UT and ES in hoods. Pareto optimality analysis indicates drops are more effective for crouched postures, while hoods optimize upright postures. These findings guide cyclists and coaches in selecting postures that balance aerodynamic efficiency and physiological demands for specific conditions.
This study investigated the relationship between running power and VO2 across several submaximal incremental running speeds. Furthermore, it also determined whether the relationship between running power and VO2 changes after an endurance training period of 20 weeks, and, finally, the intrasubject differences of the relationship between VO2 and running power after the endurance training period. Experiment I comprised 81 graded exercise tests from nationally trained runners (30 females and 51 males; 26.6 [7.0] y), and 18 (5 females and 13 males; 25.6 [5.2] y) were evaluated pretraining and posttraining (experiment II). Linear and multiple regression analyses were used to model the relationship between VO2 and running power. In experiment I, a strong correlation was observed between running power and VO2 (R2 = .88, P < .001). However, a multiple regression including heart rate, performance level, and sex revealed similar VO2 estimation (R2 = .89, P < .001). After 20 weeks of endurance training (experiment II), VO2 increased significantly (P < .001), while running power remained unchanged (P = .332). Additionally, individual regression analyses revealed significant changes in the slope and the intercept of the VO2-running power relationship. Running power strongly correlates with VO2 but lacks sensitivity to detect metabolic adaptations after an endurance training period, as the metabolic demand changes for a given running power. These findings highlight the need for individualized and constant adaptation of the relationship between running power and VO2. Therefore, coaches should use running power as a complementary metric and periodically recalibrate individual power-VO2 relationships rather than relying on a fixed predictive equation for longitudinal monitoring.
We investigated whether a 4-day intake of hydrogen-rich water (HRW) improves finswimming performance and alters physiological and perceptual markers including blood lactate, rating of perceived exertion, and oxidative stress. Eight females and 4 males, age 21 (5) and 19 (1) years, maximal oxygen consumption 45.0 (2.5) and 52.2 (1.7) mL·kg-1·min-1, performed 3 sets of 4 reps of 50-m surface finswimming sprints in a morning session, and a 400-m surface time trial in the afternoon on the same day. Participants consumed either HRW (hydrogen concentration 0.9 ppm) or placebo, starting 3 days prior to the experimental sessions. Intake was 1260 mL per day for 3 days, and 1680 mL on the day before the 400-m time trial. After each 4 × 50-m set and 400-m trial, blood lactate and rating of perceived exertion were measured. Oxidative stress was evaluated by plasma protein carbonyls at scheduled time points. After a 1-week washout period, the experiment was repeated with participants receiving the alternate intervention. NCT05799911. HRW did not significantly improve morning 50-m sprint times (0.5%, P = .12) but afternoon 400-m time trial was improved by 0.6% (P = .003). The differences between HRW and placebo administration on blood lactate, rating of perceived exertion, and protein carbonyls were not significant (all P ≥ .12). Short-term HRW supplementation provides a modest yet meaningful performance improvement of 0.6% in middle-distance (400-m surface) finswimming. However, its effects on repeated sprint performance, blood lactate, perceived exertion, and oxidative stress appear limited.