20-m Sprint Research Articles

Warm-up optimization in amateur male soccer players: A comparison of small-sided games and traditional warm-up routines on physical fitness qualities

The aim of this study was to compare the effects of small-sided soccer games (SSSGs) and traditional warm-up (TWU) routines on physical fitness qualities in soccer players. Following a between-subject, randomized design, amateur-level soccer players were assigned to a SSSG warm-up (n = 10; age: 19.3 ± 2.8 years) or TWU group (n = 10; age: 19.3 ± 2.4 years). Players completed multiple trials of 10-m and 30-m linear sprints, change-of-direction speed (CODS) tests, and countermovement jumps (CMJ) prior to and following the warm-up routine. Separate mixed ANOVAs were performed to assess group effects (SSSG vs. TWU), time effects within each group (pre- vs. post-warm-up), and their interaction for each physical fitness quality. No significant interaction effects were observed for any dependent variable. Significant improvements were evident between baseline and follow-up measurements for 10-m sprint time (p = 0.002, Hedges' g effect size [g] = 0.59) and CMJ variables (height: p = 0.016, g = 0.20; power: p = 0.003, g = 0.19; force: p = 0.002, g = 0.14) in the TWU group and for CODS performance time (p = 0.012, g = 0.51) and CMJ variables (height: p < 0.001, g = 0.46; power: p = 0.002, g = 0.35; force: p = 0.001, g = 0.27) in the SSSG warm-up group. Both SSSG and TWU protocols improved selected physical fitness qualities with SSSG more effective at improving CODS and CMJ performance, and TWU more effective at improving linear speed. Soccer coaches may choose between SSSG or traditional warm-up activities according to player needs and preferences; however, the superior effects of SSSG suggest it might offer greater benefits than TWU in preparing players for optimal physical output.

Comparison of two 8-week training interventions on the athletic performance of padel players

Padel is an intermittent racket sport played in pairs (2 vs. 2) on a small-sized grass court (20 x 10 m), involving high physical fitness demands for the players. Therefore, this study aims to compare the effect of two 8-week in-season training programs on the athletic performance of male padel players. Participants (age, 22.1±0.8; body height, 182.0±1.0; body mass, 74.7±0.7) were randomly assigned to the integrated training group (IG, n=12) and non-integrated training group (NIG, n=12). The IG trained inside the padel court, integrating neuromuscular exercises with sport-specific (i.e., use of the racket) technical actions. The NIG trained outside the padel court, performing the same neuromuscular exercises and sport-specific technical actions as the IG, although not simultaneously. Before and after the intervention, athletes were assessed for their hand-grip strength, two legged and one-legged Abalakov jump, bench press performance, padel stroke velocity, cardiorespiratory endurance (30-15IFT), 5-m and 10-m linear sprint time and change of direction ability at 90º and 180º using left and right leg. Both groups improved their scores on Abalakov jump tests, bench press performance, stroke velocity, cardiorespiratory endurance (30-15IFT), and change of direction ability at 90º and 180º (all changes p&amp;lt;.05; effect size = 0.22-2.58). The IG improved stroke velocity compared to NIG (p&amp;lt;.05), and only the IG showed pre-post improvements (p&amp;lt;.05; effect size = 0.30-0.76) in change of direction ability at 90º and 180º involving the non-dominant leg (i.e., turn to the right). An 8-week in-season integrated training approach and a non-integrated training approach may induce similar improvements in athletic performance among highly trained male padel players. However, the neuromuscular training program involving an integration of padel-specific and non-specific training exercises may induce greater improvements in padel-specific performance (i.e., stroke velocity) and change of direction speed ability, particularly in movements involving the non-dominant leg.

The Effect of Sex, Maturity, and Training Status on Maximal Sprint Performance Kinetics.

The development of sprint running during youth has received renewed interest, but questions remain regarding the development of speed in youth, especially the influences of sex, training, and maturity status. One hundred and forty-seven team sport trained (69 girls; 14.3 [2.1]y) and 113 untrained (64 girls; 13.8 [2.7]y) youth completed two 30-m sprints separated by 2-minute active rest. Velocity was measured using a radar gun at >46Hz, with power and force variables derived from a force-velocity-power profile. Boys produced a significantly higher absolute peak power (741 [272] vs 645 [229]W; P < .01) and force (431 [124] vs 398 [125]N; P < .01) than girls, irrespective of maturity and training status. However, there was a greater sex difference in relative mean power and peak velocity in circa peak height velocity adolescents (46.9% and 19.8%, respectively) compared with prepeak height velocity (5.4% and 3.2%) or postpeak height velocity youth (11.6% and 5.6%). Sprint development in youth is sexually dimorphic which needs considering when devising long-term training plans. Further research is needed to explore the independent, and combined, effects of sex, training, and maturity status on sprint performance kinetics in youth.

RELAÇÃO ENTRE O DESEMPENHO DE SALTO E SPRINT EM VELOCISTAS ADOLESCENTES

ABSTRACT Objectives: This study aimed to examine the relationship between vertical jumping at forces of specific time phase and sprint performance in teenage sprinters. Methods: Fifteen male teenage sprinters (age: 14±2 years, height: 168±2 cm, weight: 61±1 kg) participated in the study. The subjects performed the following bilateral/unilateral jumps on a force platform: a) squat jump (SJ), b) unilateral SJ (USJ), c) 40cm drop jump (DJ), and d) 20cm unilateral DJ (UDJ). The 60m sprint test was administered on the second day. Brower split timers were positioned to record subjects’ 5m, 10m, 50m and 60m split times. The variables for inclusion were vertical jump height, maximum force, and force output at 120ms in all jumps and sprint time measures. Results: The results of the Pearson Product Moment Correlation analysis showed that SJ120ms was correlated to 5m and USJ120ms was correlated to 10m. UDJ120ms showed a stronger correlation with 50m than DJ120ms. Although significant correlations using maximum force and height were observed, there were inconsistent results between bilateral and unilateral jumps. Conclusion: Our results highlighted that jumps that have similar form with certain force outputs at specific event timing could more precisely predict sprint performance in teenage sprinters. USJ120ms and UDJ120ms could better predict the acceleration (10m) and high-speed phase (50m) in sprint performance, respectively. Moreover, coaches and practitioners should be cautious when using only jump height or maximum force to predict sprint performance, since the results could be inaccurate when specific movement variables are not thoughtfully considered. Level of evidence III.

Effect of Blood Flow Restriction Training Program on Strength of Lower Limb in Young Football Players

Background of the Study: Football is a sport which involve running activities. The strength of the lower limb determines the efficiency of the football player. There are numeral studies that are done to improve the strength of lower limb. This study has been focussing to evaluate the effectiveness of blood flow restriction training program to improve the strength of lower limb in young football players. The intent of the study is to find out the effects of blood flow restriction training programs to improve the strength of lower limb in young football players. Methodology: It is an experimental study with 15 football players with age group of 16-21 years were recruited from Dr.M.G.R Educational and Research Institute Velappanchavadi, Chennai. It is a simple random sampling method, collegiate male football players who are not been trained in specific lower limb strengthening program in past 6 months included in this study. Exclusion criteria; Recent fracture of players, Acute inflammation, Hypermobility of joints, any haematological condition. Results: In this study the strength of the lower limb 1RM (in kg) has increase with mean difference of 17.60 by BFR training with P VALUE &gt; 0.0001. 60m sprint test (in seconds) has reduced with the mean distance of 0.241 by BFR training with P value &gt; 0.0003 both outcomes found effective after BFR training among young football players. Conclusion: The study concluded that blood flow restriction training program yield the significant improvement in strength and speed of the young football players.

플라이오메트릭 훈련과 축구 훈련이 대학 축구동아리 참여자의 순발력과 민첩성에 미치는 영향

The purpose of this study is to provide data on the performance improvement experienced by the members of the soccer club by examining the effect that 8 weeks of plyometric and soccer training had on the power and agility of the members of the university men’s soccer club who were in their 20s. The 30 healthy male students belonging to Busan’s 00 university soccer club were separated into a soccer training group (n=10), a plyometric training group (n=10), and a soccer+plyometric training group (n=10). Power and agility were each measured before and after the 8 week training program. Power was measured using the standing vertical jump and a 30m sprint. While agility was measured using a 10m shuttle run and side steps. As a result of this study, it is shown that after the ploymetric training and soccer+plyometric training, there was improvement in power. And after the soccer training, plyometric training, and soccer+plyometric training, there was improvement in agility. Based on these results, if a study is conducted where the player’s position and physical movement are taken into consideration, it will provide useful information to the members of the soccer club.

Association Analyses of Physical Fitness Parameters and Anxiety Symptoms in Chinese College Students

Poor physical fitness is related to many negative health outcomes, including mental disorders. However, the relationship between physical fitness and anxiety symptoms among college students remains unclear. Therefore, this study investigated whether physical fitness is related to anxiety symptoms in Chinese college students. Cross-sectional data were collected from 6635 men and 4482 women. Physical fitness was measured via a 50-m sprint, a sit-and-reach test, vital capacity, and a standing long jump for both sexes; 1000-m run and pull-up tests for males; and 800-m run and sit-up tests for females. The seven-item Generalized Anxiety Disorder Scale (GAD-7) was used to evaluate anxiety symptoms. Multivariate linear regression showed that better physical fitness was related to lower GAD-7 scores. In addition, multivariate logistic regression analysis showed that better ability in the 50-m sprint, sit-and-reach test, pull-up test, and vital capacity was related with a lower risk of anxiety symptoms in males, and better ability in the 800-m run and standing long jump was related with a lower risk of anxiety symptoms in females. In conclusion, physical fitness was inversely associated with anxiety symptoms in male and female college students. This association was also independent of confounding factors.

Speed, Agility and Power Potential of Young Basketball Players

Background. As basketball constantly evolves, physical performance becomes more and more important. Physical fitness assessments are the most reliable way to find out at what level a basketball player is prepared to perform. Therefore, the main aim of this research was to determine if the speed, agility and power of under-16-year-old (U16) basketball players is related to their playing positions. Methods. The study included (n = 40) young basketball (aged 14.99 ± 0.84 years) players. The variables included height, body mass, body mass index (BMI), fat-free mass (FFM), the percentage of body fat (BF%), the counter movement jump (CMJ), counter movement jump with free arms (CMJ free arms), squat jump (SJ), 5m, 10m, 15m and 20m sprints, T-test, Illinois test and 505 test. Results. The results showed that centers are taller and heavier than other positions, while the speed, agility and power of forwards are greater than other positions. Conclusions. At the youth basketball level there are differences in anthropometric and physical fitness testing results between positions. This supports the fact that athletes may be more likely to be selected for a given position based on how their anthropometric and athletic abilities pair with the demands of a given position. Keywords: body composition; physical testing; playing position; performance.

Relationship between body mass index and physical fitness index in Chinese college students: Results from a cross-sectional survey.

To explore the cross-sectional relationship between the body mass index (BMI) and physical fitness index (PFI) of Chinese college students. In total, 30 497 (male 16 197, 55.5%) Chinese college students aged 19-22 were tested for height, weight and five physical fitness indicators (50-m sprint, sit and reach, standing long jump, 1000/800-m run, pull-up/bent-leg sit-up). Stratified according to age and gender, according to BMI percentile, divided into BMI < 10th Percentile (A), 10th ≤ BMI < 25th Percentile (B), 25th ≤ BMI < 75th Percentile (C), 75th ≤ BMI < 90th Percentile (D), BMI ≥ 90th Percentile (E), a total of 5 groups, and the PFI composed of 5 indicators of physical fitness was calculated according to age and gender. The comparison of PFI between different BMI groups was carried out using the effect size, and the non-linear relationship between BMI-Z and PFI was analyzed. The relationship between BMI-Z and PFI of male and female college students in China showed an inverted "U"-shaped curve. With comparable BMI, PFI change was greater in males than in females. The relationship between BMI and PFI of Chinese college students is nonlinear. The physical fitness level of college students who are underweight or overweight and those with obesity is lower than that of normal-weight students.

The Association of Body Mass Index and Fat Mass with Health-Related Physical Fitness among Chinese Schoolchildren: A Study Using a Predictive Model.

Body fat mass (FM) has advantages over body mass index (BMI) in terms of accuracy of fitness assessment and health monitoring. However, the relationship between FM and fitness in Chinese children has not yet been well studied. This study aimed to investigate the relationship between health-related physical fitness, BMI, and FM, which was estimated using a predictive model among elementary schoolchildren in China. This cross-sectional study included 2677 participants (boys, 53.6%; girls, 46.4%) who underwent anthropometric measurements (height, weight, BMI, and FM) and five health-related fitness tests: 50-m sprint (speed), sit and reach (flexibility), timed rope-skipping (coordination), timed sit-ups (muscular endurance), and 50-m × 8 shuttle run (endurance). In boys, BMI showed a positive correlation with speed (p &lt; 0.001) and endurance (p &lt; 0.006) tests and a negative correlation with flexibility (p &lt; 0.004) and coordination (p &lt; 0.001) tests. In girls, a positive correlation between speed (p &lt; 0.001) and endurance (p &lt; 0.036) tests was observed. Both BMI and FM (estimated using the predictive model) were strongly associated with the health-related physical fitness of elementary schoolchildren. Our findings indicate that health-related physical fitness was similarly affected by FM and BMI. As FM can be quantified, it could therefore be used to develop strategies and intervention programs for the prevention and management of obesity in children.

Impact of Antarctic krill oil supplementation on skeletal muscle injury recovery after resistance exercise.

Antarctic krill oil (KO) is a natural source of n-3 polyunsaturated fatty acids (n-3 PUFAs), and is rich in phospholipids, Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA), astaxanthin, flavonoids, vitamins, trace elements, and other bioactive substances. KO has been confirmed to have anti-inflammatory and immunomodulatory effects. n-3 PUFAs also have been purported to improve the recovery of muscular performance. Moreover, the phospholipids present in KO can enhance n-3 PUFA bioavailability because of its higher absorption rate in plasma compared to fish oil. Astaxanthin, found in Antarctic KO, is a red carotenoid and powerful antioxidant that inhibits oxidative stress after intense exercise. Hence, we examined the effect of KO supplementation on the recovery of exercise by measuring muscular performance, oxidant/antioxidant and anti-inflammatory activity, and the markers of muscle damage following a rigorous bout of resistance exercise. 30 college-aged resistance-trained males (20.4 ± 0.92years, 74.09 ± 7.23kg, 180.13 ± 4.72cm) were randomly supplemented with 3g/d KO or placebo (PL) for 3days and continued to consume after resistance exercise for 3days until the experiment finished. Before supplementation, pre-exercise performance assessments of knee isokinetic strength, 20m sprint, hexagon test, and blood serum creatine kinase (CK), lactate dehydrogenase (LDH), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), reactive oxygen species (ROS), malondialdehyde (MDA), interleukin-2 (IL-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were completed. Then after 3days of supplementation, participants completed a bout of muscle-damaging exercise, and subsequently, they performed and repeated the exercise performance assessments and blood-related indicators tests immediately (0h), as well as at 6, 24, 48, and 72h post-muscle-damaging exercise. Compared to the PL group, the serum CK of KO group was significantly lower at 24h and 48h post-exercise; the hexagon test time of the KO group was significantly lower than that of the PL group at 6h and 24h post-exercise; the KO group's isokinetic muscle strength showed different degrees of recovery than that of the PL group at 24h and 48h, and even over-recovery at 72h post-exercise; the SOD level of the KO group was significantly higher than that of the PL group at 0, 6, and 24h after exercise; the T-AOC level of the KO group was significantly higher than that of the PL group at 0, 6, and 72h after exercise; the MDA level of the KO group was significantly lower than that of the PL group at 6h; and there was no significant difference in serum IL-2, IL-6, and TNF-α between the two groups. Our results demonstrated that 3g/d KO supplementation and continued supplementation after exercise can alleviate exercise-induced muscle damage (EIMD) and promote post-exercise recovery.

Correlation between Clark angle and Performances in Icelandic Female Basketball Players

Basketball is a highly anaerobic game, that consists of high-intensity efforts followed by lower-intensity efforts. Postural deformities can be a limiting factor in achieving maximal performances in basketball. Flat feet are one of the most common deformities and they can lead to discomfort and pain. In this research we made an attempt to link the degree of feet flatness with sports performances in elite Icelandic female basketball players. A sample of 15 basketball players was tested on a podoscope to establish the degree of feet flatness and all participants performed drop jump, countermovement jump, 20m sprint and agility t-test. No significant correlation was observed, which means that feet flatness was not a limiting factor. However, we state that only strong and healthy feet might lead to excellent performance.

Longitudinal association of childhood physical activity and physical fitness with physical activity in adolescence: insights from the IDEFICS/I.Family study.

This study aimed to examine associations of early childhood physical fitness and physical activity (PA) with PA during later childhood/early adolescence while accounting for gender differences. We selected data of N= 4329 children from the IDEFICS/I. Family cohort (age 2.4-11.7 years) with data on baseline fitness and accelerometer measurements. At baseline, physical fitness tests were conducted including Flamingo balance, Backsaver sit and reach, Handgrip strength, Standing Long Jump, 40-m sprint and 20-m Shuttle run (to estimate cardio-respiratory fitness levels). PA was measured with Actigraph accelerometers over 3 days at baseline (ActiTrainer or GT1M) and 7 days at follow-up (GT3X). Evenson cutpoints were used to determine moderate-to-vigorous PA (MVPA) time, and children with ≥60mins/day of average MVPA were deemed as having met WHO guidelines at baseline and follow-up. Linear and logistic regressions were performed to examine longitudinal associations between meeting WHO guidelines, MVPA, and physical fitness tests at baseline with meeting WHO guidelines and MVPA at follow-up. Models were conducted on the entire sample, the sex-stratified sample, and stratified by sex and pubertal status at follow-up. Results showed that meeting WHO guidelines for MVPA at baseline was positively associated with MVPA (Standardized Beta (B) = 0.13, 95%CI:(5.6;11.1)) and meeting WHO guidelines at follow-up for the entire sample (OR = 2.1, 95%CI:(1.5; 3.14), and stratified by males (OR = 2.5, 95%CI:(1.5; 4.1)) and females (OR = 1.8, 95%CI:(1.0; 3.2)). This was also found for both male pre/early pubertal and pubertal groups but only in the female pre/early pubertal group, and not the female pubertal group (MVPA: B = .00, 95%CI:(- 6.1; 5.6), WHO: OR = 0.61, 95%CI:(0.23;1.6)). Models indicated that Standing Long jump, 40-m sprint, Shuttle run and Flamingo balance at baseline were associated with MVPA and meeting the guidelines at follow-up. Meeting WHO guidelines and certain fitness tests at baseline were strongly associated with MVPA and meeting WHO guidelines at follow-up, but this association varied with sex and pubertal status. Consequently, these findings underline the importance of ensuring sufficient physical activity in terms of quality and quantity for children at the earliest stages of life. ISRCTN62310987.

Physical fitness assessment in wheelchair basketball: A mini-review.

Wheelchair basketball (WB) is a Paralympic sport ideated for people with motor disabilities, and the research on this topic still requires attention. It is fundamental to evaluate physical fitness characteristics with appropriate tests and standardized routines to plan and monitor the training. Considering that a standard operating procedure is a document that makes the test battery replicable, the objective of the present study was to review the literature on physical fitness assessment in WB players and to create a standard operating procedure. Studies were collected from different databases, and after a screening process, data were discussed narratively. Only 18 articles met the eligibility criteria. The test batteries presented similarities in different studies. The suggested standard operating procedure consists of 10-min warm-up followed by handgrip evaluation (only if the instrument is available), 20-m sprint test, maximal pass, modified push-up, back scratch test, and the Yo-Yo intermittent recovery test adapted test Version 1.

PHYSIOLOGICAL PROFILE OF SPEED, AGILITY AND JUMPING ABILITY OF ELITE U16 BASKETBALL PLAYERS

The purpose of the study was to record the physiological profile of the U16 elite men basketball players of national teams per playing position as well as to compare the differences of those physiological profiles between the playing positions. The study involved 17 young male basketball players (average weight 84 kg, average height 1.97 cm, average age 15.9 years). Players were classified according to their positions in Guards (G: n = 7), Forwards (F: n = 6), and Centers (C: n = 4). In order to determine the physiological profile of the elite players of the study, tests were performed which were divided into 3 characteristics: speed (5m-10m Sprint), agility (T-drill) and jumping ability / anaerobic power (CMJ, DJ, SJ). In the inductive analysis, the possible differences between the different positions of the players were examined through the one-way ANOVA tests. The main findings suggest that the physiological profile of speed, agility and jumping ability of the U16 male players of the Greek National Basketball Team is at a high level. Specifically, the Guards recorded an average of jump height 41.73 cm for the 3 trials (CMJ, SJ, DJ) and times 0.73 ± 0.03 (s), 1.87 ± 0.04 (s) for the 5m. and 10m. sprints and 8.39 ± 0.23 (s) for the T-drill test. Respectively, the Forwards of the research recorded average jump heights of 40.12 cm for the 3 trials (CMJ, SJ, DJ) and times 0.75 ± 0.07 (s), 1.93 ± 0.12 (s) for the 5m, and 10m sprints, and 8.48 ± 0.47 for the T-drill test. Finally, the Centers recorded an average of jump height 42.82 cm for the 3 trials (CMJ, SJ, DJ) and times 0.74 ± 0.05 (s), 1.89 ± 0.04 (s) for the 5m. and 10m. sprints and 8.48 ± 0.31 (s) for the T-drill test. The findings showed that there were no differences between the 3-position players in the 5m / 10m speed tests as well as in the T-drill agility test. On the other hand, in the jump tests, paradoxically, the elite U16 players from the Centers position had the best performance in general in the 3 jump tests and in particular in the CMJ and SJ and the Guards players had the best performance in the DJ. The Forwards position players had the worst performance in all 3 jump tests.

Association between BMI and health-related physical fitness: A cross-sectional study in Chinese high school students.

Existing studies reporting on the levels of physical fitness among high school students use relatively few fitness tests for indicators of physical fitness, thus, incomprehensively evaluating the levels of physical fitness. Therefore, this study investigated the relationship between body mass index (BMI) and physical fitness index (PFI) by investigating five physical fitness indicators and calculating PHI. Anthropometric measurements and indicators from five measures of physical fitness (50-m sprint, sit and reach, standing long jump, 800/1,000-m run, pull-up/bent-leg sit-up) were assessed. BMI was calculated to classify individuals into underweight, normal weight, overweight, and obese categories. Z-scores based on sex-specific mean and standard deviation were calculated, and the sum of Z-scores from the six fitness tests indicated the PFI. The findings were fitted to a linear regression model to elucidate the potential relationship between BMI and PFI. In total, 176,655 high school students (male: 88,243, female: 88,412, age: 17.1 ± 1.05 years, height: 168.87 ± 11.1 cm, weight: 62.54 ± 15.15 kg) in Jinan, China, completed the physical fitness tests between 2020 and 2021. The one-way ANOVA models showed that PFI in the normal category was significantly higher as compared to all the other BMI categories within both male and female groups (p < 0.001), and PFI in the obese category was significantly lower as compared to all the other BMI categories for both male and female groups (p < 0.001). The association between PFI and BMI showed an inverted U-shape relationship. This study demonstrated that BMI affects the PFI in both males and females. As compared to the obese and overweight categories based on BMI, significantly higher scores of PFI were observed for males and females.

A systematic review of velocity and accelerometer thresholds in soccer

Background: Velocity and acceleration have been highlighted as the most critical variables in soccer. However, there is a consensus gap in defining different levels of effort. Aim: The purpose of this systematic review is to identify if it is a consensus in those articles that proposed a threshold to establish (i) movement intensity at different velocities using tracking systems and (ii) accelerations using inertial measurement units, classifying the justification methods. Method: A systematic review of Cochrane Library, EBSCO, PubMed, Scielo, Scopus, SPORTDiscus, and Web of Science databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: Of the 1983 studies initially identified, 39 were thoroughly reviewed, and their outcome measures were extracted and analyzed. Conclusion: The 40-m maximal linear sprint and physical fitness tests are the most commonly used methods to generate speed and acceleration thresholds in soccer. However, there is substantial heterogeneity in locomotor test procedures and workload zones established from these performance data. Studies diverged when considering the use of individualized thresholds. The low sampling rate (≤ 10 Hz) in the publications calculating acceleration and deceleration demands should also be interpreted cautiously. The present study collected evidence to help professionals process and interpret external load data. More interventional work is needed to confirm the value of fitness-based individualizations.

Sprint and upper limbs power field tests for the screening of low bone mineral density in children.

Background: The possibility of carrying out screening, with acceptable accuracy, of a child's bone mass status based on a physical fitness test can advance the concept of health-related physical fitness. In addition, the relevance of the applicability of this type of screening in educational environments is mainly due to the difficulty of direct assessments of bone health indicators. This study aimed to propose cut-off points for physical fitness tests based on children's bone health indicators. Methods: This is a two-phase cross-sectional study. Phase-1: 160 children (6-11years-old) performed the 20-m sprint test (20-mST) and the 2kg medicine ball throw test (2kgMBTT). Areal bone mineral density (aBMD) and content was assessed by DXA. The area under the ROC curve greater than 70% was considered valid. Phase-2: It was carried out a secondary analysis in a sample with 8,750 Brazilians (6-11years-old). The percentile values (identified in phase-1) were used to identify the values of the cut-off points in the unit of measurement of the tests. The validation of the cut-off points found was by odds ratio values and p ≤ 0.05. Results: Phase 1: The areas under the ROC curve were 0.710, 0.712 (boys and girls-20-mST), 0.703, and 0.806 (boys and girls-2kgMBTT) with total spine and pelvis aBMD as the outcome. Phase 2: From percentile values, we find valid cut-off points in the Brazilian sample (OR > 3.00; p < 0.001) for boys and girls. Values ranged between 5.22s-4.00s to 20-mST and between 125.0cm-160.0cm to 2kgMBTT. Conclusion. The 20-mST and the 2kgMBTT presented sufficient accuracy for the screening of children aged between 6 and 11years with greater chances of having low aBMD in the total spine and pelvis, with valid cut-off points.

Effect of Resisted Sled Sprints in Sprint Start and Acceleration Performance: Preliminary Results

The purpose of the study was to examine the effect of resisted sled sprints (RSS) on the biomechanical parameters of the first steps of short&#x0D; acceleration sprints. Five track and field athletes performed 10-m sprints using the semi-standing (SSS) and the 3-point (TPS) starting techniques. The RSS condition was conducted with a load of 9.7% ± 0.3 of body mass. Results of the 2 (start technique) × 2 (loading) × 3 (steps) revealed significant (p .05) were evident for flight time and sled pulling force. In conclusion, regardless of the starting technique, RSS should be controlled the avoidance of the excessive loading that was observed at the sprint start.

The Three-Level Model of Factors Contributing to High-Intensity Intermittent Performance in Male Soccer Players.

High-intensity intermittent performance in soccer is widely assessed using the yo-yo intermittent recovery level 2 test (YYIR2). This test is usually associated with aerobic-anaerobic performance. However, less is known about the direct or indirect contributions of abilities, including the anaerobic component. This study aims to propose a three-level model of factors contributing to YYIR2 performance, based on the investigation of relationships with aerobic endurance, repeated-sprint ability (RSA), and the linear and change-of-direction speed and power variables. Eighteen soccer players performed the YYIR2, with a 20-m shuttle run test (20mSR), an RSA test with change-of-direction, 5-m and 20-m sprints, and a 505 test, countermovement jump, squat jump, and drop jump. The results showed a significant relationship between the YYIR2 distance and the 20mSR distance (r = 0.721, p = 0.001), as well as with the RSA test mean time (r = -0.594, p = 0.009). In the second level, the 20mSR distance performance was not associated with any of the speed and power variables. However, the RSA test mean time correlated with the 5-m sprint (r = 0.587, p = 0.010), 20-m sprint (r = 0.702, p = 0.001), and 505 test (r = 0.585 p = 0.011) performance. In the third level, the 20-m sprint time was related to the squat jump (r = -0.577 p = 0.012) and countermovement jump (r = -0.768 p &lt; 0.001) heights. In addition to aerobic endurance, this study highlights the importance of the anaerobic component in YYIR2 performance. More specifically, aerobic endurance (52%) and RSA (36%) are the main determinants of YYIR2 performance. Subsequently, the RSA performance is determined by the linear (34-49%) and change-of-direction speed (35%), while the explosive power of lower limbs contributes to sprinting performance (33-59%). Coaches should focus on the development of these abilities to improve the high-intensity intermittent performance of soccer players.