JOURNAL OF SPORTS SCIENCE AND MEDICINE (JSSM) 是一本非盈利性科学电子期刊，发表运动医学和运动科学领域的研究和评论文章以及案例研究。 JSSM 每季在 3 月、6 月、9 月和 12 月发布。 JSSM 还出版社论、“致编辑的信”部分、国际和国家代表大会、小组会议、会议和专题讨论会的摘要，并可作为当前关注的重大问题的公开讨论论坛。

The Journal of Sports Science and Medicine (JSSM) is a non-profit scientific electronic journal that publishes research articles, review articles, and case studies in the fields of sports medicine and sports science. JSSM is published quarterly in March, June, September, and December. The journal also includes editorials, letters to the editor, abstracts from international and national conferences, panel meetings, and symposiums, serving as a public forum for discussing significant current issues.

《Journal of Sports Science and Medicine》（JSSM）是一份非盈利性的科学电子期刊，专注于运动医学和运动科学领域的研究、评论文章以及案例研究。JSSM 每年发布四期，分别在 3 月、6 月、9 月和 12 月。期刊还包括论文、致编辑的信件、国际和国家代表大会、小组会议、会议和专题讨论会的摘要，并为当前重大问题提供公开讨论的论坛。

Journal of Sports Science and Medicine

Tracking of markers placed on anatomical landmarks is a common practice in sports science to perform the kinematic analysis that interests both athletes and coaches. Although different software programs have been developed to automatically track markers and/or features, none of them was specifically designed to analyze underwater motion. Hence, this study aimed to evaluate the effectiveness of a software developed for automatic tracking of underwater movements (DVP), based on the Kanade-Lucas-Tomasi feature tracker. Twenty-one video recordings of different aquatic exercises (n = 2940 markers' positions) were manually tracked to determine the markers' center coordinates. Then, the videos were automatically tracked using DVP and a commercially available software (COM). Since tracking techniques may produce false targets, an operator was instructed to stop the automatic procedure and to correct the position of the cursor when the distance between the calculated marker's coordinate and the reference one was higher than 4 pixels. The proportion of manual interventions required by the software was used as a measure of the degree of automation. Overall, manual interventions were 10.4% lower for DVP (7.4%) than for COM (17.8%). Moreover, when examining the different exercise modes separately, the percentage of manual interventions was 5.6% to 29.3% lower for DVP than for COM. Similar results were observed when analyzing the type of marker rather than the type of exercise, with 9.9% less manual interventions for DVP than for COM. In conclusion, based on these results, the developed automatic tracking software presented can be used as a valid and useful tool for underwater motion analysis. Key PointsThe availability of effective software for automatic tracking would represent a significant advance for the practical use of kinematic analysis in swimming and other aquatic sports.An important feature of automatic tracking software is to require limited human interventions and supervision, thus allowing short processing time.When tracking underwater movements, the degree of automation of the tracking procedure is influenced by the capability of the algorithm to overcome difficulties linked to the small target size, the low image quality and the presence of background clutters.The newly developed feature-tracking algorithm has shown a good automatic tracking effectiveness in underwater motion analysis with significantly smaller percentage of required manual interventions when compared to a commercial software.

F. Magalhães

Z. Sawacha

R. Di Michele

M. Cortesi

G. Gatta

S. Fantozzi

Effectiveness of an automatic tracking software in underwater motion analysis.

自动跟踪软件在水下运动分析中的有效性。

Sports nutrition supplements have previously been reported to contain undeclared doping substances. The use of such supplements can lead to general health risks and may give rise to unintentional doping violations in elite sports. To assess the prevalence of doping substances in a range of high-risk sports nutrition supplements available from Dutch web shops. A total of 66 sports nutrition supplements - identified as potentially high-risk products claiming to modulate hormone regulation, stimulate muscle mass gain, increase fat loss, and/or boost energy - were selected from 21 different brands and purchased from 17 web shops. All products were analyzed for doping substances by the UK life sciences testing company LGC, formerly known as the Laboratory of the Government Chemist, using an extended version of their ISO17025 accredited nutritional supplement screen. A total of 25 out of the 66 products (38%) contained undeclared doping substances, which included high levels of the stimulants oxilofrine, β-methylphenethylamine (BMPEA) and N,β-dimethylphenethylamine (NBDMPEA), the stimulant 4-methylhexan-2-amine (methylhexaneamine, 1,3-dimethylamylamine, DMAA), the anabolic steroids boldione (1,4-androstadiene-3,17-dione) and 5-androstene-3β,17α-diol (17α-AED), the beta-2 agonist higenamine and the beta-blocker bisoprolol. Based upon the recommended dose and the potential variability of analyte concentration, the ingestion of some products identified within this study could pose a significant risk of unintentional doping violations. In addition to inadvertent doping risks, the prescribed use of 3 products (4.5%) could likely impose general health risks.

Erik Duiven

Luc J.C. van Loon

Laila Spruijt

Willem Koert

Olivier M. de Hon

Undeclared Doping Substances are Highly Prevalent in Commercial Sports Nutrition Supplements

商业运动营养补充剂中未申报的兴奋剂物质极为普遍

During full tethered swimming no hydrodynamic resistance is generated (since v = 0) and all the swimmer’s propulsive force (FP) is utilized to exert force on the tether (FT = FP). During semi-tethered swimming FP can be made useful to one of two ends: exerting force on the tether (FST) or overcoming drag in the water (active drag: Da). At constant stroke rate, the mean propulsive force (FP) is constant and the quantity FP - FST (the “residual thrust”) corresponds to Da. In this study we explored the possibility to estimate Da based on this method (“residual thrust method”) and we compared these values with passive drag values (Dp) and with values of active drag estimated by means of the “planimetric method”. Based on data obtained from resisted swimming (full and semi-tethered tests at 100% and 35, 50, 60, 75, 85% of the individual FT), active drag was calculated as: DaST = kaST .vST2 = FP - FST (“residual thrust method”). Passive drag (Dp) was calculated based on data obtained from passive towing tests and active drag (“planimetric method”) was estimated as: DaPL = Dp.1.5. Speed-specific drag (k = D/v2) in passive conditions (kp) was )25 kg.m-1 and in active conditions (ka) )38 kg.m-1 (with either method); thus, DaST &gt; Dp and DaST &gt; DaPL. In human swimming active drag is, thus, about 1.5 times larger than passive drag. These experiments can be conducted in an ecological setting (in the swimming pool) by using basic instrumentation and a simple set of calculations.

Matteo Cortesi

Giorgio Gatta

Rémi Carmigniani

Paola Zamparo

jsportscimed

Estimating Active Drag Based on Full and Semi-Tethered Swimming Tests

基于全浮和半系留游泳测试的主动阻力估算

Sprint interval exercise can cause transient, intense exercise-induced pain (EIP) during and several minutes after the activity. A hypoalgesic strategy for high-intensity exercise, such as sprint interval exercise, against EIP is necessary to maintain exercise habituation and improve training quality/exercise performance. Preexercise caffeine supplementation, a well-known ergogenic strategy, may improve sprint performance and alleviate EIP as the hypoalgesic strategy. However, whether preexercise caffeine supplementation exhibits both the ergogenic effect on sprint interval performance and the hypoalgesic effect on intensive EIP during and several minutes after high intensity sprint interval exercise remains unknown, and thus we investigated to clarify those points. In this double-blind, randomized, crossover trial, sixteen male collegiate athletes performed 3 sets of 30-sec all-out Wingate pedaling exercises at 2-min intervals. Participants ingested 6 mg·kg-1 caffeine or placebo via capsules at 60 min prior to exercise. Quadriceps EIP was measured using a visual analogue scale during and up to 20 min after exercise. The results showed that caffeine did not significantly affect peak or mean power during sprint interval exercise (peak power: P = 0.196, ηp2 = 0.11, mean power: P = 0.157, ηp2 = 0.13; interaction). No significant interactions were also found for quadriceps EIP during (P = 0.686, ηp2 = 0.03) and immediately after exercise (P = 0.112, ηp2 = 0.12), nor for changes in physiological responses (blood lactate and ammonia concentrations) and caffeine-induced side effects (all P &gt; 0.05). In conclusion, caffeine had no ergogenic or hypoalgesic effects on sprint interval exercise with intensive EIP.

Teppei Matsumura

Yuya Sakai

Kazushi Fukuzawa

Chihiro Kojima

Takeshi Hashimoto

Caffeine Exerts Neither Ergogenic nor Hypoalgesic Effects on Sprint Interval Exercise with Intensive Exercise-Induced Muscle Pain

咖啡因对伴有剧烈运动引发肌肉疼痛的短时间间隔冲刺运动既无增力效果也无镇痛效果

The relative age effect (RAE), as a widely recognized phenomenon in the field of sports, reveals the bias in talent selection across various sporting disciplines and the neglect of certain potentially gifted athletes. The study aims to analyze RAE incidence and athletic performance among the top 100 world-ranked high jump and long jump athletes, as well as to examine the differences across the five continents. Finally, successful professional athletes are divided into two groups, namely the "All-Phase Success (AS)" and the "Senior Success (SS)" based on their success during their youth. A comparison is made between the performance and age differences of these two groups. The results indicate: 1) the RAE is present across all age groups (U18, U20, Senior) and both sexes in the high jump and long jump events (except for the senior male high jump). 2) Athletes in the AS group are consistently 2-3 years younger at each key stage of their athletic careers compared to those in the SS group. 3) Relatively younger athletes exhibit higher transition rates during their youth period compared to relatively older athletes. However, despite the larger number of relatively older athletes, AS athletes still outperform SS athletes in high jump and long jump events.

Yulin Xia

Hui Zhang

Relative Age Effect Among World-Class Jump Athletes

世界级跳跃运动员中的相对年龄效应

The effects of specific training protocols to improve repeated sprint ability are well known; however, the utility of non-specific training for this purpose is doubtful. Therefore, this study aimed to compare the effects of a specific (sport-related) vs. non-specific (general physical development) eight-week training protocol on developing or maintaining repeated sprint ability in soccer players. Thirty-eight male soccer players (aged 17.1 ± 0.3 years) were randomly divided into a speed endurance group (n = 18) and a core training group (n = 20). The speed endurance group performed 4 sprints lasting 15 seconds with a recovery of 75 seconds, while the core training group performed 2 sets of 4 exercises for 30 seconds with 15 seconds of recovery. Both protocols were performed twice a week. All players performed the Running-Based Anaerobic Sprint Test (6 consecutive 35-meter sprints with 10-seconds recovery intervals). A mixed two-way ANOVA was performed with no significant effects in the interaction term. On average, the speed endurance and the core training groups improved their repeated sprint ability by 7.9% and 8.0%, respectively, from pre- to post-assessment (p &lt; 0.001, η2p = 0.459). No significant between-group differences were detected for the Running-Based Anaerobic Sprint Test total time or maximum power. In principle, specific and non-specific low-volume training protocols may improve repeated sprint ability over eight weeks in soccer players. However, the improvements may have been derived from the continued soccer-specific training, which is the reason why future studies should include a passive control group and test whether high session volumes produce different results.

Olavo Maciel

Ricardo Martins

Fábio Y. Nakamura

Pedro Figueiredo

José Afonso

Ivan Baptista

The Effect of Speed Endurance Versus Core Training on The Repeated Sprint Ability of Youth Male Soccer Players – A Randomized Controlled Trial

速度耐力与核心训练对青年男性足球运动员反复冲刺能力的影响——一项随机对照试验

This study compared inter-individual variability in the adaptive responses of cardiorespiratory fitness, anaerobic power, and motor abilities of male volleyball players to high-intensity interval training (HIIT) prescribed as repetitive drop jumps (interval jumping) and running-based intervals (interval running). Twenty-four collegiate volleyball players were equally randomized to two training groups executing 11 minutes of interval running or interval jumping during which they ran or repeated drop-jumps for 15 seconds, alternating with 15 seconds of passive recovery. Before and after the 6-week training period, aerobic fitness, cardiac function, and anaerobic power were evaluated using a graded exercise test, impedance cardiography, and a lower-body Wingate test, respectively. Additionally, linear speed, agility, and jumping tests determined motor abilities. Both interventions significantly enhanced maximum oxygen uptake (V̇O2max), velocity associated with V̇O2max, first and second ventilatory thresholds (VT1 &amp; VT2), maximal cardiac output (Q̇max), stroke volume (SVmax), peak and average power output, vertical jump, change of direction, and linear sprint speed. Interval jumping group demonstrated a significantly greater improvement in squat jump (p = 0.001; 95% CI: 2.51-5.42) and countermovement jump (p = 0.001; 95% CI: 2.11-4.61) compared to interval running group. Conversely, interval running group elicited a greater enhancement in sprint speed (p = 0.002; 95% CI: 2.53-5.71) than interval jumping group. Examining the individual residual in the adaptive responses revealed that interval running induced more homogenized adaptations across individuals in VT1 (p = 0.04; 95% CI: 0.03-1.33), Q̇max (p = 0.03; 95% CI: 0.04-1.64), SVmax (p = 0.04; 95% CI: 0.02-1.75), and maximal sprint speed (p = 0.01; 95% CI: 0.72-1.95) in contrast to interval jumping. However, the uniformity of adaptations in countermovement jump in response to interval jumping surpassed that of interval running (p = 0.02; 95% CI: 0.08-1.32). Although both training modalities effectively improved the mentioned variables concurrently, tailoring the HIIT intervention to the reference intensity and training modality specific for each quality may enhance measured quality.

Xuefeng Zhao

Minying Lu

The Impact of Running-Based and Drop Jumping Interval Interventions on Cardiorespiratory Fitness and Anaerobic Power of Collegiate Volleyball Players: A Comparative Analysis of Inter-Individual Variability in the Adaptive Responses

基于跑步和跳跃间歇干预对大学生排球运动员心肺适能和无氧功率的影响：适应性反应中个体间差异的比较分析

The purpose of this study was to compare the adaptations in muscular strength, power, and landing forces of young female volleyball players enrolled in two experimental programs: one using smaller formats of the game (SFG) and the other using larger formats of the game (LFG), with a third group serving as a control. This study employed a randomized controlled design, with an 8-week intervention period and pre- and post-intervention evaluations. Fifty-six trained/developmental participants (age: 14.7 ± 0.5 years) voluntarily participated in this study. Each experimental group received additional training twice a week. The SFG group participated in 2v2 and 3v3 formats on smaller courts (covering 2/6 of the court's available zones) with a regular net, while the LFG group played in 4v4 and 5v5 formats on larger courts (covering 4/6 of the court's available zones). Assessments were conducted using force platforms and included the following tests: (i) isometric mid-thigh pull test (IMTP), measuring peak force; (ii) squat jump test (SJ), measuring peak force; (iii) countermovement jump test (CMJ), measuring peak power and landing force; and (iv) drop jump test (DJT), measuring the reactive strength index. Significant differences emerged post-intervention across all outcomes (p &lt; 0.05). The SFG exhibited significantly greater IMTP peak force compared to both the LFG (p = 0.012) and control groups (p = 0.035). Additionally, the SFG showed significantly greater SJ peak force than the LFG (p = 0.036) and control groups (p = 0.023). Regarding CMJ peak power, significantly higher values were observed in the SFG compared to the LFG (p = 0.042) and control groups (p = 0.046). Moreover, the SFG had significantly lower CMJ peak landing force than both the LFG (p = 0.049) and control groups (p = 0.046). Finally, RSI was significantly higher in the SFG than in the LFG (p = 0.046) and control groups (p = 0.036). This study highlights the significant benefits of incorporating 2v2 and 3v3 SFG formats to enhance muscular strength, power, and landing forces in young female volleyball players, contrasting with less effective outcomes observed with 4v4 and 5v5 LFG formats, suggesting potential neuromuscular advantages crucial for improving volleyball performance.

YuQing Duan

Li Wang

Qi Liu

Wanyu Huang

Smaller Formats of Volleyball Lead to Greater Improvements in Lower Limb Strength and Power, As Well As Reductions in Landing Forces: A Randomized Controlled Study in Girls

小规模排球训练能显著提升下肢力量与爆发力，并减少落地冲击力：一项针对女孩的随机对照研究

Abbreviation	jsportscimed
Journal Impact	2.47
Quartiles(Global)	SPORT SCIENCES(Q2)

ISSN	1303-2968
h-index	81

Publication Information	Publisher: Department of Sports Medicine, Medical Faculty of Uludag University，Publishing cycle: Quarterly，Journal Type: journal，Open Access Journals: No
Basic data	Year of publication: 2002，Proportion of original research papers: 94.03%，Self Citation Rate:8.30%， Gold OA Rate: 98.02%
Average review cycle	网友分享经验：偏慢,4-8周
Average recruitment ratio	网友分享经验：容易

Journal of Sports Science and Medicine

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Effectiveness of an automatic tracking software in underwater motion analysis.

Undeclared Doping Substances are Highly Prevalent in Commercial Sports Nutrition Supplements

Estimating Active Drag Based on Full and Semi-Tethered Swimming Tests

Caffeine Exerts Neither Ergogenic nor Hypoalgesic Effects on Sprint Interval Exercise with Intensive Exercise-Induced Muscle Pain

Relative Age Effect Among World-Class Jump Athletes

Caffeine Exerts Neither Ergogenic nor Hypoalgesic Effects on Sprint Interval Exercise with Intensive Exercise-Induced Muscle Pain

Relative Age Effect Among World-Class Jump Athletes

The Effect of Speed Endurance Versus Core Training on The Repeated Sprint Ability of Youth Male Soccer Players – A Randomized Controlled Trial

The Impact of Running-Based and Drop Jumping Interval Interventions on Cardiorespiratory Fitness and Anaerobic Power of Collegiate Volleyball Players: A Comparative Analysis of Inter-Individual Variability in the Adaptive Responses

Smaller Formats of Volleyball Lead to Greater Improvements in Lower Limb Strength and Power, As Well As Reductions in Landing Forces: A Randomized Controlled Study in Girls