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Most injuries that dancers sustain are to the lower extremities, specifically the foot and ankle region. Numerous potential risk factors have been examined for dancer injuries such as technical mistakes and fatigue. The purpose of this study was to compare landing kinematics and kinetics during jumps that are common in dance pre and postfatigue. Ten adolescent advanced level dancers participated in this study. Subjects completed 3 split leaps and 3 center leaps before and after a fatigue protocol performed on a stationary bike. Live motion capture was used to record landing kinematic and kinetic data. Results of this study showed a significant increase in ankle eversion and external rotation angles for center leaps from pre- to postfatigue protocol (P = .020 and P = .020, respectively) as well as significant increases in ankle eversion and knee adduction moments for center leaps (P = .020 and P = .036, respectively). These results show that after a fatigue protocol, there are changes to the kinematics of dancers that may make them more susceptible to ankle injury.

Purpose: This investigation sought to determine industry perceptions of postgraduate strength and conditioning (S&C) degrees to understand whether graduates are equipped for the demands of sport performance service roles. Methods: Survey data were collected from 111 participants employed as performance staff or in a role that recruits and supervises performance staff. The survey consisted of 3 main sections: (1) perceptions of career-development opportunities in S&C, (2) perception of S&C postgraduate programs, and (3) perceptions of employability in S&C. Exploratory factor analysis was conducted to identify the key factors considered to be of greatest relevance to career progression in S&C. Results: A 2-factor solution was achieved for each of the 3 sections, resulting in 6 total factors. These factors are Academic and Professional Development, Mentorship and Sport Diversity, Student Preparation, Require Greater Emphasis, Testing and Training, and Personal and Professional Growth. Conclusions: Postgraduate S&C programs require a broad range of placement/internship opportunities to (1) provide diverse experiences, (2) allow students to build contacts and develop professional networks, (3) gain exposure to working in high-performance environments and multidisciplinary teams, and (4) access high-quality mentors. Alongside the ability to deliver training and testing, graduates should be equipped with strong organizational and relationship-building skills. Improved graduate capabilities can raise the standards of the profession and result in enhanced service provision to athletes.

Purpose: The first heart-rate (HR) -variability (HRV) -derived threshold based on detrended fluctuation analysis alpha 1 (DFA a1) has shown inconsistent agreement with the gas-exchange threshold (GET). This study examined whether a custom method of computing the first HRV threshold (HRVT₁) based on individual HRV characteristics would improve agreement. Methods: Fourteen participants underwent ramp incremental testing measuring gas-exchange variables and RR intervals. Comparisons were made between the oxygen consumption ${\displaystyle {(\dot{\mathrm{V}}\mathrm{O}}_2)/\mathrm{HR}}$ at the GET versus the ${\dot{\mathrm{V}}\mathrm{O}}_2/\mathrm{HR}$ at the standard DFA a1 = 0.75 (HRVT_1s) or a custom value (HRVT_1c) based on the DFA a1 midway between the maximum seen during the early ramp incremental and 0.5. Results: Mean values for GET ${\dot{\mathrm{V}}\mathrm{O}}_2$ versus HRVT_1s ${\dot{\mathrm{V}}\mathrm{O}}_2$ and GET_HR versus HRVT_1sHR were statistically different (25.4 [3.3] vs 29.8 [6.8] mL·kg⁻¹·min⁻¹, P = .01, d = 0.80; 131 [11] vs 146 [22] beats·min⁻¹, P = .005, d = 0.91). There were no statistical differences when using the HRVT_1c (25.4 [3.3] vs 25.1 [5.7] mL·kg⁻¹·min⁻¹, P = .77, d = 0.08; 131 [11] vs 132 [17] beats·min⁻¹, P = .65, d = 0.12). Equivalence between GET and HRVT_1c ${\dot{\mathrm{V}}\mathrm{O}}_2/\mathrm{HR}$ was also verified. Mean maximal DFA a1 during the early ramp incremental was 1.52 (0.22) with mean HRVT_1c of 1.01 (0.11). Pearson r correlation coefficients were between .67 and .70 for all GET to HRVT₁ comparisons. The second HRV threshold and respiratory compensation point parameters showed agreement and correlations in line with prior studies. Conclusions: The HRVT_1c showed stronger agreement to GET parameters than seen using the HRVT_1s. It is recommended that evaluations of the HRVT₁ consider this approach in determining the HR and ${\dot{\mathrm{V}}\mathrm{O}}_2$ at this threshold.

Purpose: The popularity of fencing and intense sports competition has burdened adolescents with excessive training, harming their immature bodies. Traditional training methods fail to provide timely movement corrections and personalized plans, leading to ineffective exercises. This paper aims to use artificial intelligence technology to reduce ineffective exercises and alleviate the training burden. Methods: We propose an action recognition algorithm based on the characteristics of adolescent athletes. This algorithm uses multimodal input data to comprehensively extract action information. Each modality is processed by the same network structure, utilizing attention mechanisms and adaptive graph structures. A multibranch feature fusion method is used to determine the final action category. Results: We gathered the fencing footwork data set 2.0. Our model achieved 93.3% accuracy, with the highest precision at 95.8% and the highest F1-Score at 94.5% across all categories. It effectively recognized actions of adolescents with different heights and speeds, outperforming traditional methods. Conclusion: Our artificial intelligence-based training solution improves training efficiency and reduces the training burden on adolescents.

Background: This prospective observation study explored the association between 24-hour movement behaviors and fundamental movement skills (FMS) in Chinese preschoolers during the COVID-19 pandemic. Methods: Four hundred and eighteen preschoolers (226 males; 4.0 [0.6] y old) from Zhuhai, China, completed the device-based physical activity (PA) and sedentary behavior measures, and sleep duration was reported by parents at baseline (October 2021 to December 2021). FMS was assessed using the Test of Gross Motor Development: Third Edition at 1-year follow-up (October 2022 to December 2022). The compositional analysis and isotemporal substitution were used. Results: Moderate to vigorous PA (MVPA) was positively associated with locomotor skills and ball skills (P < .05), and light physical activity was negatively associated with locomotor skills (P < .05) during the COVID-19 pandemic. FMS improvements were linked to the addition of MVPA at the expense of light physical activity, sedentary behavior, and sleep. The estimated detriments to FMS were larger in magnitude than the estimated benefits of time reallocation from MVPA to light physical activity, sedentary behavior, and sleep. Conclusions: This study provides evidence about 24-hour movement behaviors and FMS during the COVID-19 pandemic and highlights the importance of participating in MVPA to improve preschoolers’ FMS development during the COVID-19 era.

Purpose: To analyze the evolution of the world ranking in swimming over the last 10 years, with particular attention to the effects of COVID-19 on the different levels of participating athletes. Methods: The top 200 world-ranked entries in all swimming events (50-m pool) were collected from 2013 to 2022. A mathematical model (Gaussian model) was proposed to evaluate the ranking progression for different performance levels (clusters) according to distance, stroke, and gender. The model was applied both with and without the COVID season data. Results: Overall results indicated a general progression in world rankings over the last 10 years, except for the COVID season and the post-Olympic year(s), with peak results in the 2021 postpandemic (Olympic) year. The gender gap in World Aquatics points scoring has shown an increasing gap in favor of males since 2017, reaching 1.5% in 2022. The top 200 positions of world rankings were grouped into 3 different clusters defined by the 23.3%, 66.5%, and 100% of ranked male swimmers (or 31.5%, 72.5%, and 100% for females) and with average World Aquatics scores of 910 (12), 858 (10) and 816 (11) points (907 [13], 847 [11], and 802 [12] for females). The Gaussian model showed a gap averaging ∼21 to ∼36 points between performance curves with or without COVID season data, with larger gaps for female rankings and cluster-3 swimmers. Conclusions: These results suggest that, given the lower relative performance of female swimmers in the different clusters of world rankings, female events may provide an opportunity to enter international-level swimming.

There is little evidence that body size alters exogenous glucose oxidation rates during exercise. This study assessed whether larger people oxidize more exogenous glucose during exercise than smaller people. Fifteen cyclists were allocated into two groups based on body mass (SMALL, <70 kg body mass, n = 9, two females) or (LARGE, >70 kg body mass, n = 6) matched for lactate threshold (SMALL: 2.3 ± 0.4 W/kg, LARGE: 2.3 ± 0.3 W/kg). SMALL completed 120 min of cycling at 95% of lactate threshold₁. LARGE completed two trials in a random order, one at 95% of lactate threshold₁ (thereby exercising at the same relative intensity [RELATIVE]) and one at an absolute intensity matched to SMALL (ABSOLUTE). In all trials, cyclists ingested 90 g/hr of ¹³C-enriched glucose. Total exogenous glucose oxidation was (mean ± SD) 33 ± 8 g/hr in SMALL versus 45 ± 13 g/hr in LARGE-RELATIVE (mean difference: 13 g/hr, 95% confidence interval [2, 24] g/hr, p = .03). Large positive correlations were observed for measures of exogenous carbohydrate oxidation versus body size (body mass, height, and body surface area; e.g., body surface area vs. peak exogenous glucose oxidation, r = .85, 95% confidence interval [.51, .95], p < .01). When larger athletes reduced the intensity from RELATIVE to ABSOLUTE, total exogenous glucose oxidation was 39 ± 7 g/hr (p = .43 vs. LARGE-RELATIVE). In conclusion, the capacity for exogenous glucose oxidation is, on average, higher in larger athletes than smaller athletes during exercise. The extent to which this is due to higher absolute exercise intensity requires further research, but body size may be a consideration in tailoring sports nutrition guidelines for carbohydrate intake during exercise.

Purpose: The aim of this study was to investigate the effect of agility ladder training combined with plyometric or multidirection speed drills, on performance in young female volleyball players. Methods: Seventy-six young female volleyball players were randomly distributed into 3 maturity-matched groups: (1) the agility ladder + plyometric drills group, (2) the agility ladder + multidirection speed drills group, and (3) the control group. Both experimental groups followed a 6-week training program, twice weekly, in addition to the regular volleyball training sessions, while the control group participated only in the regular volleyball training sessions. Assessments pretraining and posttraining included countermovement jump, 20-m sprint, and agility T test.  Results: Both experimental groups improved T-test performance (P < .005) but only agility ladder + multidirection speed drills group outperformed the control group (P < .05). Conclusions: Agility ladder training programs combined with either plyometric or speed drills can improve change of direction performance in young female volleyball players but only the combination of agility ladder with multidirection speed drills is more effective than volleyball training per se. The small effectiveness of these protocols may be attributed to the short training period, or to the fact that training elements were combined in a single session. This hypothesis remains to be further investigated.