Decreased neural drive affects the early rate of force development after repeated burst-like isometric contractions.

The neural drive to the muscle is the primary determinant of the rate of force development (RFD) in the first 50 ms of a rapid contraction. It is still unproven if repetitive rapid contractions specifically impair the net neural drive to the muscles. To isolate the fatiguing effect of contraction rapidity, 17 male adult volunteers performed 100 burst-like (i.e., brief force pulses) isometric contractions of the knee extensors. The response to electrically-evoked single and octet femoral nerve stimulation was measured with high-density surface electromyography (HD-sEMG) from the vastus lateralis and medialis muscles. Root mean square (RMS) of each channel of HD-sEMG was normalized to the corresponding M-wave peak-to-peak amplitude, while muscle fiber conduction velocity (MFCV) was normalized to M-wave conduction velocity to compensate for changes in sarcolemma properties. Voluntary RFD 0-50 ms decreased (d = -0.56, p < 0.001) while time to peak force (d = 0.90, p < 0.001) and time to RFDpeak increased (d = 0.56, p = 0.034). Relative RMS (d = -1.10, p = 0.006) and MFCV (d = -0.53, p = 0.007) also decreased in the first 50 ms of voluntary contractions. Evoked octet RFD 0-50 ms (d = 0.60, p = 0.020), M-wave amplitude (d = 0.77, p = 0.009) and conduction velocity (d = 1.75, p < 0.001) all increased. Neural efficacy, i.e., voluntary/octet force ratio, largely decreased (d = -1.50, p < 0.001). We isolated the fatiguing impact of contraction rapidity and found that the decrement in RFD, particularly when calculated in the first 50 ms of muscle contraction, can mainly be explained by a decrease in the net neural drive.

Early parathyroid hormone (PTH) level as a predictor of post-surgical hypoparathyroidism.

INTRODUCTION: Post-operative hypocalcemia and postoperative persistent hypoparathyroidism remain the most common complications after thyroidectomy. Many approaches have been developed to prevent them, but actually, a common protocol is not yet individuated. MATERIALS AND METHODS: We retrospectively analyzed the results of a prospectively collected database. We dosed PTH preoperatively and 4 h after surgery (PTH_4); calcium was evaluated preoperatively, on the first (I_POD) and on the second postoperative day (II_POD). Hypocalcemia was defined when calcium <8 mg/dl. PTH_4 and I_POD calcium serum levels are identified to predict postoperative hypocalcemia. RESULTS: Three hundred and forty-eight patients were enrolled, 37 patients resulted as hypocalcemic on I_POD and 41 on the II_POD. PTH_4 is related to I_POD (p < 0.001, r = 0.45) and II_POD (p < 0.001, r = 0.44) calcemia. PTH_4-cut-off predicting I_POD hypocalcemia was 10.50 pg/ml (sensitivity: 78.7%, specificity: 72.7%). A PTH_4 value of 11.5 pg/ml is able to predict hypocalcemia during II_POD (sensitivity: 76.5%, specificity: 69.2%). We set up a combined test to predict II_POD hypocalcemia, using PTH_4 and I_POD calcium (sensitivity: 77.8%, specificity: 89.9%). CONCLUSION: This research shows the association between PTH_4 and postoperative hypocalcemia. The PTH_4 cut-off to predict I_POD-hypocalcemia was 10.5 pg/ml. We analyzed the calcemia trend during the postoperative period and we realized a combined test using PTH_4 and I_POD-calcemia. This test improves the accuracy of the previous test. Further studies, in particular multicentric, with a larger sample are necessary to validate the combined model.

Relative age effect reversal on the junior-to-senior transition in world-class athletics.

The relative age effect (RAE) is a selection bias resulting from the interaction between the selected dates and birthdates. Nevertheless, the impact of birthdate on the junior-to-senior transition in international track and field is unclear. This study aimed to quantify the RAE's magnitude and test if birthdate affects the junior-to-senior transition rate. The birthdate and performances of 5,766 sprinters (female: 51.0%) and 5,863 jumpers (female: 45.9%) were collected. Elite athletes (operationally defined as the World's all-time Top 200, 100 and 50 athletes) were identified according to Under 18 and Senior categories. Skewed quartile distributions were observed in the Under 18 (effect size ranged = 0.15-0.10) but not in the Senior category. RAE magnitude increased according to performance level (i.e., from Top 200 to Top 50) and was higher in males than females. Relatively younger athletes showed significantly higher transition rates with a higher chance of maintaining top level in the senior category (odds ratio (OR) ~ 1.64). The probability of maintaining success was lower for sprinters than jumpers (OR ~ 0.70), influenced by decade of birth and continental place but similar for male and female athletes. Data corroborate that relatively younger athletes are disadvantaged in the junior category but advantaged when transitioning to the senior category.

Commentary: Comment and reflection about Mental health outcomes of the Daily Mile in elementary school children: a single-arm pilot study. The implementation of the Daily Mile in the school context.

In 'Mental health outcomes of the Daily Mile in elementary school children: a single-arm pilot study', Arkesteyn et al. (Child and Adolescent Mental Health, 2022) discussed and investigated the effect of a classroom activity break, named The Daily Mile, on pupils' self-esteem, self-perception competence, and mental health. Starting from the interesting and novel results of Arkesteyn et al. (Child and Adolescent Mental Health, 2022), this comment focuses on the concurrent evidence about the effect of The Daily Mile on pupils' physical and mental health. Overall, this comment would reflect and critically review considerations for future research on the topic and to adopt it in the school context.

Performance progression of elite jumpers: Early performances do not predict later success.

This study aimed (a) to estimate the transition rate for top 50 ranked track and field jumpers, (b) to compare the performance progression of top 50 ranked senior jumpers (top50 senior) to those who failed to be top 50 ranked in the senior category despite being top 50 ranked in the under 18 category (only U18), and (c) to verify whether relative age effect may at least partially explain the differences in the two above-mentioned subgroups. The career performance trajectories of 5981 athletes (2837 females) competing in jump events from 2000 to 2019 were extracted from the World Athletics database. The all-time top 50 ranked athletes for each age from 16 years to senior category were identified. Performance progression characteristics were compared using linear mixed-effects model. Only 8% of males and 16% of females top 50 ranked at the age of 16 years managed to be included among the top50 senior. Only U18subgroup made the first appearance in the database (at 15-16 years) and reached the peak performance (at 20 years) earlier than top50 senior (17-18 and 26-27 years, respectively). The relative age effect was largely present in Only U18 but not in top50 senior subgroups. Most of the early-successful U18 world-class jumpers did not manage to maintain the same level of competitiveness in adulthood since they experienced a plateau in performance from 20 years of age. Conversely, top 50 ranked senior jumpers continued to produce consistent performance improvement up to 26-27 years of age.

Corrective procedures remove relative age effect from world-class junior sprinters.

This retrospective study investigated whether corrective adjustment procedures can remove the relative age effect (RAE) from world-class junior sprinters at the beginning of their career. A total of 2,918 male and 3,029 female athletes competing in sprint races (100 m, 200 m, and 400 m) of the World Athletics lists between 2000 and 2018 were considered. Longitudinal quadratic trendline equations across ages 16-25 yrs were calculated considering athletes' exact age and respective performance. Corrective adjustment calculations from the estimated longitudinal quadratic equations were applied at 16 yrs and 17 yrs. RAE was investigated for the whole sample and top-level athletes (i.e., first Top50 and Top100) considering the uncorrected and corrected performance. Moderate to large RAE was observed in Top50 and Top100 at 16 yrs. Differently, a lower RAE was observed at 17 yrs. When re-examining the data using the corrective adjustment calculations, the RAE disappeared in all sprint events and both genders at 16 yrs, while a more equal distribution was observed at 17 yrs. Corrective adjustment procedures can remove or at least reduce the RAE in world-class sprinters. Applying simple equations based on exact age might improve the accuracy of performance evaluation and talent identification in international track and field sprint competitions.

Fracture risk assessment in an Italian group of transgender women after gender-confirming surgery.

INTRODUCTION: Bone health is a critical issue in transgender women (TW) health care. Conflicting results have been reported on bone status after gender-confirming surgery (GCS). No recent data in Italian TW are available. MATERIALS AND METHODS: The aim of this cross-sectional study was to evaluate fracture risk, lumbar spine BMD and 25OH vitamin D (25OHD) levels in a population of TW on estrogen replacement therapy (ERT) after GCS. We retrospectively analyzed a group of 57 TW, aged 45.3 ± 11.3 years, referred to our Gender Dysphoria Clinic, at least 2 years after GCS. Anthropometric parameters, patient compliance to ERT, biochemical and hormonal assessment, lumbar spine BMD and fracture risk were evaluated. RESULTS: Prevalence of low bone mass (Z-score ≤ -2) was 40% according to the natal gender. In this group, 17ß-estradiol levels were significantly lower (median 21 pg/ml [25th-75th percentile 10.6-48.5] vs 63 pg/ml [38.5-99.5]; p < 0.001) and a higher prevalence of low compliance to ERT was recorded (83% vs 29%; p < 0.0001) compared to those with higher bone mass. An intermediate-high fracture risk was found in 14% of the sample. A high percentage (93%) of hypovitaminosis D was present. CONCLUSIONS: TW on ERT have a high prevalence of low bone mass, significantly associated with low estradiol levels and low compliance to ERT. A high prevalence of hypovitaminosis D was highlighted. Considering that one out of seven TW showed an intermediate-high 10-year fracture risk, such risk assessment may be considered to prevent and manage osteoporosis in this clinical setting.

Training sessions with tackles impair upper-limb neuromuscular function in elite rugby union.

The aim of this study was to investigate the response to non-tackle and tackle field-based training on upper- and lower-limb neuromuscular function in elite rugby union players. Nine elite senior elite rugby union players (mean age = 21 ± 2 years; height = 184 ± 7 cm; body mass 91.0 ± 9 kg) were evaluated before and immediately following 17 training sessions. A total of 306 assessments were performed. Data on neuromuscular function of plyometric push-up and countermovement jump were calculated from force signals using inverse dynamics. The change from pre- to post-session was investigated across non-tackle and tackle training using a linear mixed model. Considering upper-limb neuromuscular function, peak concentric power [P = 0.024; ES = 0.33 95%CI (0.04, 0.62)] was significantly lower after tackle compared to non-tackle training. In addition, peak countermovement jump eccentric power was significantly lower after non-tackle compared to tackle training [P = 0.044; ES = -0.4 95%CI (-0.69, -0.1)] in lower-limb neuromuscular function. Overall, the results indicated that the type of training influences upper- and lower-limb neuromuscular function differently immediately after training. Indeed, due to physical contact, the upper-body neuromuscular function increased during tackle training. In contrast, lower-body neuromuscular function emerged only in non-tackle training, due to the greater distance covered during this type of training session. Coaches and practitioners should plan adequate weekly training sessions according to this information.

Neuromuscular efficiency in fibromyalgia is improved by hyperbaric oxygen therapy: looking inside muscles by means of surface electromyography.

OBJECTIVES: Neuromuscular efficiency (NME) is impaired in fibromyalgia (FM). Hyperbaric oxygen therapy (HBOT) is a medical treatment using 100% of oxygen through an oxygen mask. HBOT in FM induces changes in cortical excitability and a secondary reduction in pain and muscle fatigue. However, there are still no direct data indicating changes in muscle fatigue. The aim of this study was to assess whether the reduction in muscle fatigue so far attributed to a central effect of HBOT can be directly detected by means of non-invasive sEMG as a change in NME. METHODS: The study was an observational longitudinal study on changes in NME induced by 20 sessions of HBOT at 2.4 atmosphere, in 22 patients with FM (3M; 19F) (age 49.8±9.5; height 164.7±7.5; weight 63.8±12.7). sEMG was recorded in single differential configuration from the biceps brachii muscle during the 30-second fatiguing contractions using linear arrays of eight adhesive electrodes. RESULTS: Evaluations made before and immediately after the first session showed that maximal strength did not change (T0 49±20 N, T1 49±19 N, p=0.792), thus suggesting that HBOT did not induce muscle fatigue or potentiation. After 20 sessions of HBOT, NME increased from 1.6±1.1 to 2.1±0.8 (p=0.050), whereas maximal strength, EMG amplitude and muscle fibre CV did not change. CONCLUSIONS: HBOT did not improve muscle strength or change muscle fibre content, but improved the ability of the central motor command to generate the same effort (MVC) with fewer recruited fibres. Our sEMG findings underlined a modified central mechanism related to fibre type recruitment order, thus suggesting that muscle fatigue is not primarily a muscular problem, as also demonstrated by other authors with different methods.

A comparison between an ICT tool and a traditional physical measure for frailty evaluation in older adults.

BACKGROUND: Frailty is a clinical condition among older adults defined as the loss of resources in one or more domains (i.e., physical, psychological and social domains) of individual functioning. In frail subjects emergency situations and mobility levels need to be carefully monitored. This study aimed to: i) evaluate differences in the mobility index (MI) provided by ADAMO system, an innovative remote monitoring device for older adults; ii) compare the association of the MI and a traditional physical measure with frailty. METHODS: Twenty-five community-dwelling older adults (71 ± 6 years; 60% women) wore ADAMO continuously for a week. The time percentage spent in Low, Moderate and Vigorous Activities was assessed using ADAMO system. Walking ability and frailty were measured using the 400 m walk test and the Tilburg Frailty Indicator, respectively. RESULTS: Controlling for age and gender, the ANCOVA showed that frail and robust participants were different for Low (frail = 58.8%, robust = 42.0%, p < 0.001), Moderate (frail = 25.5%, robust = 33.8%, p = 0.008), and Vigorous Activity (frail = 15.7%, robust = 24.2%, p = 0.035). Using cluster analysis, participants were divided into two groups, one with higher and one with lower mobility. Controlling for age and gender, linear regression showed that the MI clusters were associated with total (ß = 0.571, p = 0.002), physical (ß = 0.381, p = 0.031) and social (ß = 0.652, p < 0.001) frailty; and the 400 m walk test was just associated with total (ß = 0.404, p = 0.043) and physical frailty (ß = 0.668, p = 0.002). CONCLUSION: ADAMO system seems to be a suitable time tracking that allows to measure mobility levels in a non-intrusive way providing wider information on individual health status and specifically on frailty. For the frail individuals with an important loss of resources in physical domain, this innovative device may represent a considerable help in preventing physical consequences and in monitoring functional status.

Running technique is more effective than soccer-specific training for improving the sprint and agility performances with ball possession of prepubescent soccer players.

Soccer-specific training is easily associable to players' sprint abilities demonstrated during a match. However, no clear evidence has been provided to show whether this approach is more effective than training focused on running techniques for sprints in prepubescent soccer players. Thus, the present study aimed at comparing the effects of these two training approaches on prepubescent soccer players' sprint performances. Ninety-five players (10±2 years) competing in local (Piedmont, Italy) Under-9 (N=21), -10 (N=24), -11 (N=25) and -13 (N=25) championships were recruited for the study. Sixty-three and 32 players were included in the running training group (RTG) and soccer-specific group (SSG), respectively. Before (PRE) and after (POST) the training period (2 weekly sessions for 12 weeks), sprint abilities were evaluated by means of four 20-m sprint tests: linear sprint (20-mL), linear sprint with ball possession (20-mLB), sprint with change of direction (20-mCoD), sprint with change of direction and with ball possession (20-mCoDB). A linear mixed model was applied to evaluate differences (P≤0.05) between the RTG and SSG in the four tests and categories, comparing PRE and POST performances. A main effect emerged for the interaction between groups, sessions (p=0.014; Between PRE ES range=0.03, 0.85; Within PRE-POST ES range=-0.45, 0.09), highlighting a POST improvement of RTG for the 20-mLB (Δ=-7.9%; ES=0.85) and 20-mCoDB (Δ=-5.9%; ES=0.33). In contrast, no improvements emerged for the SSG. The present findings indicate that the training approach of the RTG is more able to improve prepubescent soccer players' sprint performances than that of the SSG, with the emphasis on ball possession executions, which are particularly game-related.

Does Testosterone Treatment Increase Anger Expression in a Population of Transgender Men?

BACKGROUND: The acquisition of phenotypic male features in transmen with gender dysphoria requires testosterone treatment. The suppression of menses is 1 of the most desired effects. The relation between testosterone levels and human aggressive behavior has been described. However, the effects of testosterone on anger expression have been poorly investigated in trans-persons. AIM: To assess the effects of testosterone treatment on anger expression in transmen using a validated self-report questionnaire (Spielberger's State-Trait Anger Expression Inventory-2 [STAXI-2]). METHODS: 52 transmen diagnosed with gender dysphoria were evaluated before (T0) and at least 7 months after (T1) initiation of continuous gender-affirming testosterone treatment. Sociodemographic characteristics, anthropometric parameters, diagnosis of psychiatric disorders, current psychopharmacologic treatments, and life events were investigated at T0. OUTCOMES: STAXI-2 scores, serum testosterone, and estradiol levels at T0 and T1 were compared. RESULTS: Most of the sample (61.5%, n = 32) had no Axis I or II comorbidity. All subjects at T1 achieved significantly higher serum testosterone levels (5.67 ± 3.88 ng/mL), whereas no significant difference in estradiol levels was observed from T0 to T1. At T1 only 46.2% (n = 24) of the sample achieved iatrogenic amenorrhea, whereas most of the sample had persistent regular bleedings. A significant increase in STAXI anger expression and anger control scores from T0 to T1 was recorded. Patients with persistent bleedings and Axis I disorders seemed to have higher odds of expressing anger. However, circulating testosterone levels at T1 did not influence anger expression. CLINICAL IMPLICATIONS: Interestingly, despite the increase of anger expression scores, during continuous testosterone treatment, there were no reports of aggressive behavior, self-harm, or psychiatric hospitalization. STRENGTHS AND LIMITATIONS: A limitation to this study is that although the STAXI-2 is a well-validated instrument measuring anger expression, it is a self-report psychometric measure. CONCLUSION: This study demonstrates that during 7 months of continuous gender-affirming hormonal treatment, anger expression and anger arousal control increased in transmen. Persistence of menstrual bleedings and Axis I disorders, but not circulating testosterone levels, were predictive of the increase in anger expression score. Continuous psychological support to transmen during gender-affirming hormonal treatment was useful to prevent angry behaviors and decrease the level of dysphoria. Motta G, Crespi C, Mineccia V, et al. Does Testosterone Treatment Increase Anger Expression in a Population of Transgender Men? J Sex Med 2018;15:94-101.

Dancing in the golden age: a study on physical function, quality of life, and social engagement.

The aim of this study was to determine the effects of dancing activity based on different dance styles, in groups as well as with a partner, on mobility performance, quality of life and social engagement in a sample of older adults. One hundred and sixty-three older adults (mean age, 70 years; SD = 4 years) participated in a supervised dancing activity programme for 16 weeks. The dancing activity included different dance routines and was progressive in terms of motor complexity. Data on mobility, health-related quality of life and social engagement were collected before and after a 16-week training period. Significant improvements in mobility, quality of life and social engagement were noted in single as well as dual-task performance after the intervention. Our results emphasise the benefit of a 16-week dance training on multidimensional features, including physical and psychosocial domains, which are important for successful ageing.

A Longitudinal Study on the Relationship Between Aerobic Endurance and Lower Body Strength in Italian Sedentary Older Adults.

Functional aging processes are characterized by a loss of performance capabilities for most physiological systems, such as aerobic endurance and lower body strength, which are important for independent living and active aging. The present study examines the direction of influence between aerobic endurance and lower body strength over time in Italian sedentary older adults. A three-wave longitudinal model was tested using cross-lagged analysis for 202 individuals aged over 65 years (mean = 73.92, SD = 5.84; 140 females). Analysis revealed that aerobic endurance and lower body strength decline over time. In addition, greater aerobic endurance positively affected lower body strength over time; however, the converse was true only during the first period (first 6 months). These findings emphasize the importance of these relationships for the design and implementation of effective physical intervention for older adults.

Birth Advantages in Male Italian Soccer: How They Influence Players Youth Career and Their Future Career Status.

Soccer organizations generally adopt deterministic models within their talent pathways. In this framework, early ability and results are emphasized, leading to selection biases, such as birth advantages (i.e., relative age effects and birthplace effects), which research has shown affect both early developmental experiences and continued sporting involvement. Accordingly, this study aimed to (a) provide further test of birth advantages in Italian youth soccer by exploring the birth quarter (BQ) and birthplace (BP) distribution of 1050 male Italian players born between 1999 and 2001 who competed in the national U17 championship throughout the 2015-16 season and (b) investigate how birth advantages influenced selected players' future career status. Chi-square goodness-of-fit tests revealed early born players, and players born in North Italy were overrepresented at the youth level (p-values < 0.0001). Successive prospective analysis revealed only 18% of players developed into professional-level soccer players. Chi-square tests of independence indicated that players' BP was associated with their future career status (p < 0.0001), whereas their BQ was not (p = 0.459). Odds ratios showed players born in North Italy were five times more likely to complete the youth-to-senior transition than those born in South Italy. These findings highlighted environmental factors influence Italian players' early developmental experiences and their future career status.

Performance pathways in elite middle- and long-distance track and field athletes: The influence of a successful youth.

OBJECTIVES: There is limited information on the performance progression of athletics endurance athletes from junior-to-senior status and the determinants of success in adulthood. This study aimed to quantify the youth-to-senior transition rate, the likelihood of success and the relationship between youth and senior performance amongst world-class athletes competing in middle- and long-distance disciplines. DESIGN: Retrospective design examining public data between 2000 and 2019. METHODS: The performances of 4678 international athletes (45.3 % female) were analysed. World's all-time top 50 athletes were identified for U18 and Senior categories (age ≥ 20 years). Youth-to-senior transition rate and transition probabilities were calculated. Correlations between best U18 and Senior performances were determined to assess the stability of the performance. RESULTS: The youth-to-senior transition rate for top U18 athletes was low for males and females (~19 % and 21 %). Nevertheless, the probability of transition to a top senior was ~7 times higher for top U18 athletes than for non-top U18 athletes. The correlations between youth and senior best performances were low-to-high. CONCLUSIONS: Few top U18 athletes maintained top world ranking status during their senior careers. Still, they are more likely to become top senior athletes than those who did not perform at the top level in U18. The association between youth and senior performance is stronger when comparing the same discipline or when athletes competed over longer distances in their senior compared to U18 career. Being a successful youth athlete may represent a small advantage for future success, however, it does not guarantee advancement to the senior top level.

Mitigating against relative age effects in youth Track & Field: Validating corrective adjustment procedures across multiple events.

OBJECTIVES: With the aim to better identify talented Track & Field performance development, this study estimated the relationships between chronological (decimal) age with 60-m sprint, high jump, triple jump, and pole vault performance. Then, to mitigate against expected Relative Age Effects (RAEs), Corrective Adjustment Procedures (CAPs) were applied to an independent sample. DESIGN: Mixed-longitudinal design examining public data between 2005 and 2019. METHODS: The performances of 5339 Italian sprinters and jumpers (53.1 %) spanning 11.01-17.99 years of age were examined, with trendlines between chronological age and performance established. Related to an independent sample (N = 40,306; female 45.5 %), trendlines were then utilised to apply CAPs and adjust individual performance. Considering raw and adjusted performance data, RAE distributions were examined for the top 25 % and 10 % performers. RESULTS: For all male and female events, quadratic models best summarised the relationships between chronological age and performance (R2 = 0.74-0.89). When examining independent athletes in similar event, RAEs were more pronounced in males (Cramer's V = 0.35-0.14) than females (Cramer's V = 0.29-0.07). For both sexes, RAE magnitude decreased with age and increased according to performance level (i.e., Top25%-Top10%). However, following CAP applications, RAEs were reduced or removed within annual age groups and performance levels. CONCLUSIONS: With RAEs prevalent across Italian youth Track & Field events, findings validate CAPs as a strategy to account for the influence of relative age differences on athletic performance. CAPs help establish a more equitable strategy for performance evaluation and could help improve the efficacy of long-term athlete development programming.

Upper-Limb Muscle Fatigability in Para-Athletes Quantified as the Rate of Force Development in Rapid Contractions of Submaximal Amplitude.

This study aimed to compare neuromuscular fatigability of the elbow flexors and extensors between athletes with amputation (AMP) and athletes with spinal cord injury (SCI) for maximum voluntary force (MVF) and rate of force development (RFD). We recruited 20 para-athletes among those participating at two training camps (2022) for Italian Paralympic veterans. Ten athletes with SCI (two with tetraplegia and eight with paraplegia) were compared to 10 athletes with amputation (above the knee, N = 3; below the knee, N = 6; forearm, N = 1). We quantified MVF, RFD at 50, 100, and 150 ms, and maximal RFD (RFDpeak) of elbow flexors and extensors before and after an incremental arm cranking to voluntary fatigue. We also measured the RFD scaling factor (RFD-SF), which is the linear relationship between peak force and peak RFD quantified in a series of ballistic contractions of submaximal amplitude. SCI showed lower levels of MVF and RFD in both muscle groups (all p values ≤ 0.045). Despite this, the decrease in MVF (Cohen's d = 0.425, p < 0.001) and RFDpeak (d = 0.424, p = 0.003) after the incremental test did not show any difference between pathological conditions. Overall, RFD at 50 ms showed the greatest decrease (d = 0.741, p < 0.001), RFD at 100 ms showed a small decrease (d = 0.382, p = 0.020), and RFD at 150 ms did not decrease (p = 0.272). The RFD-SF decreased more in SCI than AMP (p < 0.0001). Muscle fatigability impacted not only maximal force expressions but also the quickness of ballistic contractions of submaximal amplitude, particularly in SCI. This may affect various sports and daily living activities of wheelchair users. Early RFD (i.e., ≤50 ms) was notably affected by muscle fatigability.

Two Is Better than One: Successful World-Class Sprinters Compete in Two Disciplines.

We aimed to quantify the prevalence of track and field sprinters competing at a world-class level in more than one discipline, and we describe the career characteristics of single- and double-discipline athletes in terms of peak performance and the age of peak performance. The career performance of athletes ranked in the top 200 positions of the World Athletics database in the 100 m, 200 m, and 400 m were analyzed, i.e., 5514 career profiles (49.9% female). Using binomial proportion, we calculated how many competed in only one or more than one discipline. We also compared the peak performance and the age of peak performance of athletes who competed in one vs. more than one discipline. Independent of gender, about 50% of the athletes competing in the 100 m and 200 m also competed in the other discipline (i.e., 200 m and 100 m, respectively). Differently, only 20% of the athletes competing in the 400 m also competed in the 200 m. Sprinters competing in the 100-200 m and 200-400 m couples showed better peak performance than the sprinters competing in only one discipline. Many world-class sprinters compete in two disciplines, and the 100-200 m was the most prevalent couple. Our results also suggest that sprinters who compete in two disciplines may be advantaged compared to sprinters who compete in only one event.

Youth-to-senior transition in women's and girls' football: Towards a better understanding of relative age effects and gender-specific considerations.

This study aimed to evaluate youth-to-senior transition and the relative age effect in Italian female football national teams. Birthdate data of 774 female players selected for Under 17 (N = 416), 19 (N = 265) and National Senior team (N = 93) were analysed. The youth-to-senior transition rate was determined by the number of youth players competing in the Senior National team (and vice versa), whilst birth quarter (Q) distributions with a chi-square goodness-of-fit test. Only 17.4% of youth players were able to be selected for the Senior National team, whereas 31.2% of the players reached the high-senior level without being selected for youth age groups. Data revealed a skewed birth date distribution in Under 17 and 19 teams (on average, Q1 = 35.6% vs Q4 = 18.5%) but not in the Senior National team. Youth players born in Q1 were two times more likely to be selected than in Q4. In Under 17, goalkeepers, defenders, and midfielders of Q1 players were overrepresented. However, Q4 players recorded higher conversion rates than Q1 (Q1 = 16.4% vs. Q4 = 25.0%). National youth experience may not be a prerequisite for being selected at the senior level. Moreover, this confers a higher probability of playing in the National Senior team than players not selected in youth rosters.