Sprint Speed Research Articles

Hamstrings mechanical properties profiling in football players of different competitive levels and positions after a repeated sprint protocol.

Purpose: This study compares the average speed, knee flexor peak torque and shear modulus of the hamstrings after a repeated sprint task, in football players of different competitive levels and playing positions. Methods: Fifty-four football field players without hamstring strain injury history participated, 15 being categorized as professional (2nd league) and 39 as semi-professional (17 in 3rd and 22 in 4th league). Muscle shear modulus was assessed using ultrasound-based shear wave elastography at rest and at 20% of maximal voluntary isometric effort before and immediately after the repeated sprint protocol. Results: No significant differences were seen in average sprint speed between competitive levels (p = 0.07; η2p = 0.28) and positions (p = 0.052; η2p = 0.29). Moreover, the sprint fatigue index showed no significant differences between competitive levels (p = 0.14; η2p = 0.08) and playing positions (p = 0.89; η2p = 0.05). No significant differences were observed in hamstring shear modulus changes between competitive levels (p = 0.94; η2p = 0.03) and positions (p = 0.92; η2p = 0.03). Peak torque changes also showed non-significant association with competitive levels (p = 0.46; η2p = 0.03) and positions (p = 0.60; η2p = 0.02). Conclusion: The results of this study suggest that the average sprint speed performance parameter and mechanical parameters are not able to distinguish football players of different competitive levels and positions.

Fatigue effects on the knee flexors neuromuscular parameters during repeated sprinting.

To identify at which point fatigue on neuromuscular parameters occurs in the knee flexors during a repeated sprint protocol. Physical active males without previous hamstring strain injury were recruited. Neuromuscular parameters such as peak torque (PT) and rate of torque development (RTD) were assessed after every two sprints in a 5 × (2 x 30m) repeated sprint protocol. Twenty physical active males participated in the study. A significant effect of sprint number was found (p < 0.001; η2p = 0.643) with a decreased sprint speed by 6.9% from fastest to slowest sprint. No significant differences were observed in the time between finishing the sprint and performing the first MVIC (46.3 ± 4.7s; p = 0.423), nor in the time between finishing a set and starting the next set (121.2 ± 7.6s; p = 0.503). Regarding neuromuscular parameters, the only significant difference found was in PT between before and after two sprints (117.95 ± 5.61N⋅m vs. 110.64 ± 5.71N⋅m; p = 0.048, d = 0.289) and on RTD 0-50ms before and after ten sprints (465.78 ± 223.76N⋅m/s vs. 382.30 ± 189.56N⋅m/s; p = 0.008; η2p = 0.149). A recovery time of 46s between sprints and testing neuromuscular parameters (due to experimental design) seems sufficient to restore the neuromuscular system. Therefore, it can be suggested that time recovery is the principal factor in detecting fatigue on neuromuscular parameters.

The effect of core stability training on ball-kicking velocity, sprint speed, and agility in adolescent male football players.

This study was conducted to investigate the effect of core stability training program on ball-kicking velocity, running speed, and agility in adolescent male football players. To this end, 36 male football players aged 12-14 were divided into the training group and control group. Before implementing the core stability training program, participants' ball-kicking velocity, sprint speed, and agility performance were measured with a Bushnell velocity radar gun, 20 m sprint test, and 505 agility test, respectively, in both training group and control group. After the measurements, the training group followed core stability training program three days a week, for eight weeks in addition to the routine training program, while the control group followed the routine training program only. Ball-kicking velocity, sprint speed, and agility performance were re-measured in both groups after the completion of the core stability training program. Significant improvements were detected in all parameters, i.e., ball-kicking velocity, sprint speed, and agility performance in the training group (p<0.05). On the other hand, in the control group, no significant change was detected in the ball-kicking velocity and sprint speed (p>0.05), whereas a significant improvement was observed in agility performance (p<0.05). Inter-group comparisons revealed statistically significant differences between the groups in ball-kicking velocity and sprint speed in favor of the training group (p<0.05), while no significant difference was found between the groups in agility performance (p>0.05). In conclusion, this study's findings suggest that core stability exercises can be incorporated into the routine training program of adolescent male football players.

Effects of Training With Different Hang-Power-Clean Intensities on the Maximum Dynamic Strength, Vertical Jump, and Sprint Performance of Female Handball Players.

To compare the effects of 7weeks of training with different hang-power-clean (HPC) intensities on the maximum dynamic strength, vertical jump, and sprint performance of female handball players. Professional handball athletes with at least 1year of HPC experience volunteered to participate. The athletes were balanced by position and randomly assigned to a group with HPC at 90% (HPC90%) or 50% (HPC50%) of HPC 1-repetition maximum (1RM). The training volume was equalized between groups. Pretraining and posttraining assessments included 1RM HPC, jump height in the squat jump (SJ) and countermovement jump(CMJ), and sprint speeds at 5, 20, and 30m. From pretraining to posttraining, both groups significantly increased (P ≤ .05) 1RM HPC, although a small effect size was observed in favor of HPC90%. HPC90% and HPC50% did not induce significant changes (P > .05) in the SJ and CMJ height, although for the SJ, a small effect size was observed in favor of HPC90%. Both groups induced a significant improvement (P ≤ .05) in 5-, 20-, and 30-m sprint speeds, although for all speeds, small to moderate effect sizes were observed in favor of HPC90%. Both training groups induced significant improvements in 1RM HPC and sprint speeds, whereas no significant changes were observed in vertical jumps. In addition, based mainly on the effect sizes, the HPC90% group was more effective for increasing 1RM HPC, SJ, and sprint speeds than the HPC50% group.

Computer vision-based instantaneous speed tracking system for measuring the subtask speed in the 100-meter sprinter: Development and concurrent validity study

The 100-m sprint is one of the track events, and the pace of the runner can be measured using a variety of tools, such as a hand stopwatch, timing gate, laser device, radar device, photocell timing, etc. The data measured is the mean travel time. Nonetheless, monitoring an individual sprinter's instantaneous speed tracking is essential for assisting staff trainers in developing an appropriate training schedule for the individual sprinter. The purpose of this study was to construct a computer vision-based system for assessing the sprinting speed of the 100-m subtasks and also to investigate the concurrent validity of video analysis software among athletes. Five athletes participated in the research to determine its validity. Over the course of two trials, the sprinting pace of each participant's subtasks (a 100-m split to 10 m for each subtask) was measured. The application of the computer vision-based system to video analysis software was validated using the Pearson correlation coefficient. The agreement between the two measurement systems was quantified using Bland-Altman plots. The results revealed a significant relationship between the two systems and all 100-m subtask sprinting speeds (r = 0.961–1.000, p 0.0001). The Bland-Altman analyses indicated that the mean differences in 100-m subtask speeds were consistently close to zero, falling within the 95 % limits of agreement. The scatter plot distribution showed symmetry. The computer vision-based system proved to be a valid tool, suggesting its potential value in measuring and monitoring the 100-m subtask sprinting speed of athletes.

Effect of Combined Feedback and Verbal Encouragement on Anaerobic Performance, Technical and Physiological Aspects During Small-Sided Basketball Games for Students’ Girls

Objective: The aim of this research is to determine the effect of combined feedback and verbal encouragement on anaerobic performance, technical and physiological aspects during small-sided Basketball games for adolescent schoolgirls. Material and Methods: Sixty schoolgirls were divided into 3 groups of 20 girls: control group (G1) (mean ± standard deviation (M±SD); age:15.45 ± 0.41years), verbal encouragement group (G2) (M±SD; age:15.65 ± 0.61years) and combined feedback and verbal encouragement group (G3) (M±SD; age:15.55 ± 0.51 years). Muscle power (countermovement jump (CMJ); 5-Jump-Test (5JT)), agility (Illinois-test), sprint speed (10 and 30 m)]; technical skill and heart rate (HR) responses during 3 vs. 3 small sided basketball game (SSBG) were measured. Additionally, HR was continuously recorded and video analysis was used to quantify technical actions during SSBG. Results: The results showed greater improvements in muscle power of CMJ and 5JT for G3 compared to G2 (P&lt;0.001, ES=1.21, moderate, p&lt;0.001, ES= 4.74, large, respectively) and for G3 compared to G1 (P&lt;0.001, ES= 1.72 large; p=0.001, ES =6.86 large respectively). The time in the 10 m, 30 m sprints and agility decreased more profoundly for G3 compared to G2 (p&lt;0.001, ES=4.93, large; p&lt;0.001, ES=3.27, large, p&lt;0.001, ES=1.14, large, respectively).For technical skill, the ball contacts, successful balls, number of shots and successful shots were higher in G2compared with G1 (p&lt;0.001, ES=1.48 moderate; p&lt;0.001, ES=3.83, large; p&lt;0.001, ES=1.99, large; p=0.001, ES=2.41, large respectively), higher in G3 compared with G2 (p&lt;0.001,ES=-0.89, large, p=0.001, ES=-1.48 moderate; p=0.001, ES= 3.97, large; p&lt;0.001, ES=4.93, large, respectively). Furthermore, average heart rate was higher in G3 compared with G2 and G1 (p&lt;0.001, ES = 1.06, large; p&lt;0.001, ES=4.64, large, respectively). Conclusion: These findings indicate that the combination of feedback and verbal encouragement are more effective for achieving better results in physical fitness and technical skill than verbal encouragement group and control group.

Application of arbitrary and individualized load quantification strategies over the weekly microcycle in professional soccer players.

The aims of this study were to: (a) determine the differences in external load quantification between arbitrary and individual speed thresholds over the weekly microcycle in professional soccer players, and (b) analyse the association between internal load and different external load quantification strategies (ELQSs). Ten professional outfield players were monitored during training sessions and official matches using 10 Hz GPS devices over a 6-week in-season period. The absolute and relative ("R" before the distance category) distances covered were calculated for the following external load variables: medium-intensity running distance (MIR), high-intensity running (HIR), sprint distance (SD), and very high-intensity running (VHIR). Individualized thresholds were determined based on maximal sprinting speed (MSS) and the last speed achieved during the 30-15 Intermittent Fitness Test (VIFT) of each player. In terms of match-day workload, significant differences (p < 0.05) were observed between arbitrary and individualized strategies (i.e., MSS and VIFT) for the distance covered in MIR, HIR, SD, VHIR, RHIR, RSD, and RVHIR. The MSS strategy compared to arbitrary thresholds revealed significant differences (p < 0.05) for distance covered in HIR, RHIR, and VHIR during all training sessions. The present results showed that arbitrary thresholds lead to underestimation of external load absolute and relative metrics compared to the MSS strategy throughout the microcycle. The VIFT strategy mainly revealed differences in external load quantification regarding MD compared to arbitrary thresholds. Individualized speed threshold strategies did not achieve better associations with internal load measures in comparison with arbitrary thresholds in professional soccer players.

'Setting the Benchmark' Part 1: The Contextualised Physical Demands of Positional Roles in the FIFA World Cup Qatar 2022.

This study aimed to contextualise and benchmark the positional role demands during the FIFA World Cup Qatar 2022. With FIFA's official approval, all sixty-four games were analysed during the competition (n=722) using a multi-camera computerised tracking system. During a typical FIFA World Cup Qatar 2022 match, defensive and central midfielders covered 8-19% more total distance than other positional roles (P<0.01; Effect Size [ES]: 0.8-2.5). The distances covered at higher intensities (≥20 and ≥25 km · h-1) were 16-92% and 36-138% higher for wide midfielders and wide forwards compared to central defenders, defensive and central midfielders as well as centre forwards (P<0.01; ES: 0.7-2.2 and ES: 0.6-1.4). Defensive and central midfielders covered a greater proportion of their distance at higher intensities (≥20 and ≥25 km · h-1) out-of-possession (71-83%; P<0.01; ES: 1.4-3.0), whilst attacking midfielders, wide and centre forwards more in-possession (55-68%; P<0.01; ES: 1.6-3.3). Nine out of the top ten sprint speeds attained at the tournament were from wide positional roles (35.3-35.7 km · h-1). All positional roles demonstrated a second half reduction in total distance covered compared to the first half (P<0.01; ES: 0.8-1.3). A decline between halves for the distances covered at higher intensities (≥20 and ≥25 km · h-1) were more evident in attacking midfielders, wide defenders and midfielders than for other positional roles (P<0.01; ES: 0.3-0.7). Defensive midfielders and centre forwards were found to have the highest coefficient of variation (CV: 30.9-35.9% and 67.7-67.8%) for the distances covered at higher intensities (≥20 and ≥25 km · h-1) compared to other positional roles. The current findings provide valuable contextual information about the contemporary positional demands of international football. This could be useful in the development and prescription of specific training regimes for national teams.

Does "Live High-Train Low and High" Hypoxic Training Alter Stride Mechanical Pattern During Repeated Sprints in Elite Team-Sport Players?

We examined changes in stride temporal parameters and spring-mass model characteristics during repeated sprints following a 3-week period of "live high-train low and high" (LHTLH)altitude training in team-sport players. While residing under normobaric hypoxia (≥14h/d; inspired oxygen fraction [FiO2] 14.5%-14.2%) for 14days, elite field hockey players performed, in addition to their regular field hockey practice in normoxia, 6 sessions (4 × 5 × 5-s maximal sprints; 25-s passive recovery; 5-min rest) under either normobaric hypoxia (LHTLH; FiO2 ∼14.5%, n = 11) or normoxia (live high-train low; FiO2 20.9%, n = 12). A control group (live low-train low; FiO2 ∼20.9%, n = 9) residing in normoxia without additional repeated-sprint training was included. Before (Pre)and a few days (Post-1) and 3weeks (Post-2) after the intervention, stride mechanics were assessed during an overground repeated-sprint test (8 × 20m, 20-s recovery). Two-way repeated-measures analysis of variance (time [Pre, Post-1, and Post-2] × condition [LHTLH, live high-train low, and live low-train low]) were conducted. Peak sprinting speed increased in LHTLH from Pre to Post-1 (+2.2% [2.0%]; P = .002) and Post-2 (+2.0% [2.4%]; P = .025), with no significant changes in live high-train low and live low-train low. There was no main effect of time (all P ≥ .062), condition (all P ≥ .771), or a significant time × condition interaction (all P ≥ .230) for any stride temporal variable (contact time, flight time, stride frequency, and stride length) or spring-mass model characteristics (vertical and leg stiffness). Peak sprinting speed improved in elite field hockey players following LHTLH altitude training, while stride mechanical adjustments to repeated overground sprints remained unchanged for at least 3weeks postintervention.

Effects of Vitamin D Supplementation in Elite Athletes: A Systematic Review.

Deficiency in vitamin D has been shown to increase the risk of injury. To synthesize current placebo-controlled randomized trials investigating the effect of vitamin D supplementation in elite athletes on (1) aerobic capacity; (2) anaerobic measures, such as strength, speed, and anaerobic power; (3) serum biomarkers of inflammation; and (4) bone health. Systematic review; Level of evidence, 1. A literature search was conducted on November 30, 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included were randomized, placebo-controlled studies of longer than 2 weeks on subjects with active participation in organized sport. Excluded were nonrandomized controlled trial study designs, vitamin D administration routes other than oral, studies that did not use vitamin D supplementation as the sole intervention, and studies with nonathletic or military populations. Out of 2331 initial studies, 14 studies (482 athletes) were included. Of the 3 studies that assessed aerobic capacity, 2 demonstrated significantly greater improvements in maximal oxygen uptake and physical working capacity-170 (P < .05) in supplemented versus nonsupplemented athletes. Measurements of anaerobic power and strength were consistently increased in supplemented groups compared with nonsupplemented groups in 5 out of the 7 studies that assessed this. Of the 6 studies that assessed sprint speed, 4 found no significant difference between supplemented and nonsupplemented groups. Aside from 1 study that found significantly lower interleukin-6 levels in supplemented athletes, measures of other inflammatory cytokines were not affected consistently by supplementation. The 4 studies that assessed markers of bone health were conflicting regarding benefits of supplementation. One study found demonstrated improvements in bone mineral density in response to supplementation (P = .02) compared with control whereas another found no significant difference between supplemented and nonsupplemented groups. However, in 3 other studies, serum biomarkers of bone turnover such as bone-specific alkaline phosphatase, parathyroid hormone, and N-terminal telopeptide appeared to be higher in subjects with lower serum vitamin D levels (P < .05). Results of this systematic review indicated that the greatest benefit of vitamin D supplementation in elite athletes may be improving aerobic endurance, anaerobic power, and strength. More research is needed to determine the effect of vitamin D supplementation on bone health and injury risk in this population.

Current practices in physical fitness assessment and monitoring among coaches of individual and team sports: a survey in Portugal, Spain, and Romania.

The objective of this study was to characterize surveyed coaches and elucidate the practices of physical fitness assessment and monitoring for both male and female athletes across three countries. A total of 165 coaches participated by completing a comprehensive 32-question survey. Pre-season assessments are a priority for coaches, with a significant range from 60.5% to 87.7% in Romania, while Portuguese and Spanish coaches tend to prefer testing during the competition (26.3% and 16.9%, respectively). Portuguese and Spanish coaches predominantly favor aerobic tests (50% and 46.8% respectively), whereas Romanian coaches exhibit a preference for sprint (56.9%) and skill tests (52.3%). Notably, change of direction tests are less commonly employed, ranging from 10.5% to 21% across the countries. In terms of exercise intensity determination, Portuguese coaches predominantly employ maximal heart rate (31.6%), while Spanish coaches often rely on the 220-age formula or perceived exertion (27.4%). For strength assessment, Portuguese coaches lean towards direct (34.2%) or estimated (31.6%) maximal repetition methods. When it comes to maximal speed sprint, Portuguese and Romanian coaches show preference (50% and 43.1% respectively), while Spanish coaches exhibit a relative lack of emphasis on individualized speed measures (37.1%). Perceptual scales are the preferred method for recovery monitoring, with adoption rates of 57.9% in Portugal, 53.2% in Spain, and 44.6% in Romania. In summary, this study underscores the distinct assessment and monitoring practices employed by coaches in Portugal, Spain, and Romania. These findings are in alignment with established literature standards, highlighting the diversity of approaches used in different countries.

Effects of Ostarine and Endurance Training on Some Functional, Hematological, and Biochemical Parameters in Male Rats

Background: Non-steroidal Selective Androgen Receptor Modulators (SARMs) are currently a group of drug candidates with anabolic effects, tissue selectivity, and the potential to improve the therapeutic process in a number of socially significant diseases. There is insufficient data on their effects during exercise and on their adverse side effects. Objectives: Our objective was to examine the role of selective androgen receptor modulators for the physical working capacity of the body, hematological and biochemical parameters, and to evaluate any side effects of SARMs. We studied the effects of ostarine (S-22, MK-2866, GTx-024, Enobosarm) alone or in combination with submaximal training in sexually mature male Wistar rats. Methods: The rats used were divided into a treadmill-trained group and a sedentary group. Half of each group received either ostarine or vehicle for 8 weeks (n = 10 each). We performed functional tests and blood analysis at the end of the experiment to analyze clinical chemistry and hematological indicators. Results: Ostarine did not affect maximal sprint speed, VO2max, and running economy, while submaximal training increased these parameters. Ostarine increased total plasma cholesterol and energy expenditure and decreased plasma glucose concentration. Neither treatment changed the oxygen-carrying capacity of the blood, the respiratory quotient, the concentration of triglycerides and LDL-cholesterol, or creatine kinase. Combined treatment neutralized the negative effect of ostarine on plasma total cholesterol levels. Conclusions: Ostarine did not affect the examined hematological and physical working capacity parameters, but it changed some clinical chemistry indicators. Training improved the physical working capacity but did not affect the clinical chemistry and hematological parameters. Further research is needed to clarify other aspects of the influence of non-steroidal SARMs on the physical working capacity and possible side effects during long-term use, as their administration, along with physical activity, is becoming popular among healthy adult bodybuilders in gyms.

Does Sled Training with a Load of 10 Kilograms Have an Effect on the Speed of College Student Soccer Players?

Study purpose. Running speed is an ability soccer players need to build attack and defence. There needs to be more research in football that applies sleds using specific loads to improve the running ability of college student soccer players. This study aims to analyze the effect of sled training with a load of 10 kilograms on the running speed of college student soccer players. Materials and methods. This study uses a quantitative approach with a quasi-experimental design research type, with the research design used being a one-group pretest-posttest design. The sample used in this research was 14 students taken from a population of 95 individuals using random sampling techniques. The study sample used had characteristics of age 18 ± 0.75 years, height 169.42 ± 5.84 cm, weight 58.5 ± 4.21 kg, and BMI 20.44 ± 2.00. Treatment was carried out for six weeks with a frequency of three times a week. The 20-meter sprint speed test was used as an instrument for collecting speed data. The data analysis technique uses a paired samples t-test at a significance level (α) 0.05. The prerequisite test used is the Shapiro-Wilk test. Results. The research showed increased players’ running speed obtained from the pretest results of 4.48 ± 0.291 and the post-test results of 4.15 ± 0.266 from the 20-meter sprint test. Conclusions. Based on the results of the paired sample t-test, it can be concluded that there is a significant increase in the running speed of college student soccer players using 10 kg sleds.

Comparison of kinematics and kinetics between unassisted and assisted maximum speed sprinting

ABSTRACT Producing comparable/greater ground reaction forces (GRFs) at faster running speeds is beneficial for sprint performance, and assisted sprint training is used to induce faster running speed conditions. This study aimed to demonstrate the characteristics of assisted sprinting at the maximal speed phase and investigate acute differences to control sprinting. Fifteen sprinters completed control and assisted (5 kg) sprints over force platforms. Assisted sprinting increased running speed (9.3% mean difference), while propulsive mean force (−4.3%) and impulse (−12.4%) decreased, suggesting that running speed improvements were caused primarily by assisted pulling force rather than improvements in anteroposterior force production of athletes. In addition, vertical mean force increased (4.2%), probably due to braking mean force (34.2%) and impulse (32.5%) increases. Magnitude of control trial maximum speed was achieved earlier (during acceleration) in assisted trials, and net anteroposterior (includes both braking and propulsive components) mean force (67.2%) and impulse (67.9%) increased at this matched speed, suggesting that assisted sprints could be used to practice producing greater GRFs at comparable speeds. Running speed improvement by pulling force was associated with contact time decreases (r = -.565), suggesting that shortening contact time may be important for effective assisted sprinting.

Effects of plyometric training on measures of physical fitness in racket sport athletes: a systematic review and meta-analysis.

Over the past decade, the popularity of racket sports has surged. Plyometric training (PT) has been the focus of extensive research because of the proven benefits it provides to athletes. However, there is a lack of systematic reviews and meta-analyses specifically evaluating the impact of PT on physical fitness metrics in racket sport athletes. This study aimed to conduct a comprehensive review and analysis of evidence derived from randomized controlled trials (RCTs) to evaluate the effects of PT on measures of physical fitness among racket sports athletes. The electronic databases PubMed, Web of Science, SCOPUS, and SPORTDiscus were systematically searched up to June 2023 without placing any restrictions on the publication dates. The PICOS method was adopted to establish the inclusion criteria: (a) healthy athletes who participate in racket sports; (b) a PT program; (c) a control group; (d) assessment of physical fitness components pre- and post-PT; and (e) RCTs. The records' methodological quality was assessed utilizing the Physiotherapy Evidence Database (PEDro) scale. The certainty in the evidence related to each outcome was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) assessment. A random-effects model was used to calculate effect sizes (ES; Hedges' g) between experimental and control groups. There were 14 eligible studies of moderate-to-high-quality, involving 746 athletes in total. The results revealed small-to-moderate effects (p < 0.05) of PT on muscle power (ES = 0.46), muscle strength (ES = 0.50), sprint speed (ES = 0.45), change of direction ability (ES = 0.76), and reaction time (ES = 0.67), while no clear evidence was found on balance and flexibility. The training-induced changes in muscle power showed no significant difference (p > 0.05) between youth (ES = 0.72) and adults (ES = 0.40). There were also similar muscle power improvements (ES = 0.36-0.54 vs 0.38-0.56, all p > 0.05) for a length of ≤7 weeks with ≤14 total PT sessions vs >7 weeks with >14 total PT sessions, and ≤2 weekly sessions vs >2 sessions. No adverse effects were reported in the included studies regarding the PT intervention. The certainty of evidence varied from very low to moderate. Conclusions: Our findings demonstrated that PT has positive effects on important indices of physical fitness among athletes participating in racket sports. Future studies are required to clarify the optimal doses and examine interactions among training variables to further promote the physical fitness of this specific population.

Effects of Two Different Low-Volume Resistance Training Programs Applied During the Off-Season Period on the Speed-Power Performance of Elite Youth Soccer Players.

Loturco, I, Nunes, RFH, Lampert, RR, Silva, RLP, Hespanhol, JE, Novack, LF, Conde, JHS, Pereira, LA, and McGuigan, MR. Effects of two different low-volume resistance training programs applied during the off-season period on the speed-power performance of elite youth soccer players. . J Strength Cond Res 38(3): 571-576, 2024-The aim of this study was to analyze the changes in the speed-power performance of elite youth soccer players submitted to 2 different low-volume resistance training programs during the off-season period. Twenty under-17 players were randomly allocated to "traditional nonballistic" or "ballistic training" groups. Countermovement jump (CMJ), 20-m sprinting speed, and half-squat (HS) power tests were performed after the final match of the season (pretesting session) and at the beginning of the subsequent season (post-testing session), after 4 weeks of detraining. Between-group differences were assessed using a 2-way ANOVA with repeated measures followed by the Tukey's post hoc test. Performance variations were individually analyzed with the use of the "true changes" calculation. At post-tests, CMJ height and HS power remained unchanged ( p > 0.05) but similar and significant improvements in sprint speed were observed in both groups ( p < 0.05). However, notably, a larger number of players in the ballistic group exhibited "true changes" in HS power (i.e., 55 vs. 33%, compared with the traditional group, respectively). In conclusion, either low-volume ballistic or traditional resistance training schemes were able to increase sprint speed and maintain power output during a short interseason break in youth soccer players. Despite this apparent similarity, at the individual level, ballistic movements were more efficient at improving lower-body power. Practitioners can use the strategies described here to improve the sprint and power performance of soccer players during short periods of soccer-specific training cessation.

A Systematic Review and Meta-Analysis of Wearable Satellite System Technology for Linear Sprint Profiling: Technological Innovations and Practical Applications.

Cormier, P, Meylan, C, Agar-Newman, D, Geneau, D, Epp-Stobbe, A, Lenetsky, S, and Klimstra, M. A systematic review and meta-analysis of wearable satellite system technology for linear sprint profiling: technological innovations and practical applications. J Strength Cond Res 38(2): 405-418, 2024-An emerging and promising practice is the use of global navigation satellite system (GNSS) technology to profile team-sports athletes in training and competition. Therefore, the purpose of this narrative systematic review with meta-analysis was to evaluate the literature regarding satellite system sensor usage for sprint modeling and to consolidate the findings to evaluate its validity and reliability. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, an electronic search of the databases, PubMed and SPORTDiscus (EBSCO), was conducted. Concurrent validity and reliability studies were considered, and 16 studies were retained for the review from the initial 1,485 studies identified. The effects on outcomes were expressed as standardized mean differences (SMDs, Cohen's d ) for each outcome (i.e., maximal sprint speed [MSS], the acceleration constant [τ], maximal theoretical velocity [ V0 ], relative force [ F0 ], and relative power [P max ]). Effect magnitudes represented the SMD between GNSS-derived and criterion-derived (i.e., radar and laser) and resulted in the following estimates: small for MSS ( d = 0.22, 95% CI 0.01 to 0.42), τ ( d = -0.18, 95% CI -0.60 to 0.23), V0 ( d = 0.14, 95% CI -0.08 to 0.36), relative F0 ( d = 0.15, 95% CI -0.25 to 0.55), and relative P max ( d = 0.21, 95% CI -0.16 to 0.58). No publication bias was identified in meta-analyzed studies and moderator analysis revealed that several factors (sampling rate and sensor manufacturer) influenced the results. Heterogeneity between studies was considered moderate to high. This highlighted the differences between studies in sensor technology differences (i.e., sampling rate, sensor fusion, and satellite network acquisition), processing techniques, criterion technology used, sprint protocols, outcome reporting, and athlete characteristics. These findings may be useful in guiding improvements in sprint modeling using GNSS technology and enable more direct comparisons in future research. Implementation of all-out linear sprint efforts with GNSS technology can be integrated into sport-specific sessions for sprint modeling when robust and consistent data processing protocols are performed, which has important implications for fatigue monitoring, program design, systematic testing, and rehabilitation in individual and team sports.

Validity of Inertial Measurement Units to Measure Lower-Limb Kinematics and Pelvic Orientation at Submaximal and Maximal Effort Running Speeds

Inertial measurement units (IMUs) have been validated for measuring sagittal plane lower-limb kinematics during moderate-speed running, but their accuracy at maximal speeds remains less understood. This study aimed to assess IMU measurement accuracy during high-speed running and maximal effort sprinting on a curved non-motorized treadmill using discrete (Bland–Altman analysis) and continuous (root mean square error [RMSE], normalised RMSE, Pearson correlation, and statistical parametric mapping analysis [SPM]) metrics. The hip, knee, and ankle flexions and the pelvic orientation (tilt, obliquity, and rotation) were captured concurrently from both IMU and optical motion capture systems, as 20 participants ran steadily at 70%, 80%, 90%, and 100% of their maximal effort sprinting speed (5.36 ± 0.55, 6.02 ± 0.60, 6.66 ± 0.71, and 7.09 ± 0.73 m/s, respectively). Bland–Altman analysis indicated a systematic bias within ±1° for the peak pelvic tilt, rotation, and lower-limb kinematics and −3.3° to −4.1° for the pelvic obliquity. The SPM analysis demonstrated a good agreement in the hip and knee flexion angles for most phases of the stride cycle, albeit with significant differences noted around the ipsilateral toe-off. The RMSE ranged from 4.3° (pelvic obliquity at 70% speed) to 7.8° (hip flexion at 100% speed). Correlation coefficients ranged from 0.44 (pelvic tilt at 90%) to 0.99 (hip and knee flexions at all speeds). Running speed minimally but significantly affected the RMSE for the hip and ankle flexions. The present IMU system is effective for measuring lower-limb kinematics during sprinting, but the pelvic orientation estimation was less accurate.

Effects of different plyometric training frequencies on physical performance in youth male volleyball players: a randomized trial

This study aimed to analyze the effect of plyometric training (PT) at different frequencies on jump performance, running sprint speed, and service speed in youth male volleyball players. The participants were randomly assigned to one PT session per week (Experimental Group 1, EG1, n = 15), two PT sessions per week (Experimental Group 2, EG2, n = 14), and a control group (CG, n = 13). The total weekly jumping ranged between 98 and 196 jumps (equalized between, EG1 and, EG2). The assessments performed were squat jump (SJ), countermovement jump (CMJ), CMJ-arms, drop jump (DJ), 5-m sprint, 10-m sprint, and service speed. The intragroup comparisons showed that, EG1 significantly (p &amp;lt; 0.001) improved SJ (Δ = 12.74%; d = 1.30), CMJ (Δ = 11.94%; d = 1.71), CMJ-arms (Δ = 12.02%; d = 1.47), DJ (Δ = 10.93%; d = 1.30), 5-m sprint (Δ = −4.61%; d = 0.29), 10-m sprint (Δ = −3.95%; d = 0.40) and service speed (Δ = 8.17%; d = 1.53). Similarly, EG2 significantly (p˂ 0.001) improved SJ (Δ = 11.52%; d = 1.25), CMJ (Δ = 11.29%; d = 1.38), CMJ-arms (Δ = 11.42%; d = 1.26), DJ (Δ = 13.90%; d = 2.17), 5-m sprint (Δ = −3.85%; d = 0.25), 10-m sprint (Δ = −2.73%; d = 0.25) and service speed (Δ = 6.77%; d = 1.44). The CG significantly (p &amp;lt; 0.05) improved SJ (Δ = 2.68; d = 0.28), CMJ-arms (Δ = 2.30; d = 0.35), 5-m sprint (Δ = −1.27; d = 0.10) and service speed (Δ = 1.42; d = 0.30). Intergroup comparisons revealed significantly greater improvements in all variables (p &amp;lt; 0.001) in, EG1 and, EG2 concerning to CG. However, no significant differences were found between, EG1 and, EG2. A moderate weekly PT volume, distributed in one or two sessions per week, seems equally effective.

Speed Training Practices of Brazilian Olympic Sprint and Jump Coaches: Toward a Deeper Understanding of Their Choices and Insights (Part II).

This is the second article in a three-article collection regarding the plyometric, speed, and resistance training practices of Brazilian Olympic sprint and jump coaches. Here, we list and describe six out of the ten speed training methods most commonly employed by these experts to enhance the sprinting capabilities of their athletes. Maximum speed sprinting, form running, resisted sprinting, overspeed running, uphill and downhill running, and sport-specific movement methods are critically examined with reference to their potential application in different sport contexts. In an era when sprint speed is of critical importance across numerous sports, practitioners can employ the methods outlined here to design efficient training programs for their athletes.