Journal of Strength and Conditioning Research最新文献

{"title":"Biomechanical Insights Into Rotary Inertial Devices vs. Traditional Resistance Training in Half-Squats: A Comparative Analysis of Force, Velocity, and Displacement.","authors":"Carlos Galiano, Francisco Javier Nuñez, Stuart McErlain-Naylor, Pablo Floria","doi":"10.1519/JSC.0000000000005073","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005073","url":null,"abstract":"<p><strong>Abstract: </strong>Galiano, C, Nuñez, FJ, McErlain-Naylor, S, and Floria, P. Biomechanical insights into rotary inertial devices vs. traditional resistance training in half-squats: a comparative analysis of force, velocity, and displacement. J Strength Cond Res XX(X): 000-000, 2024-Although rotary inertial devices (RIDs) have been used in resistance training for many years, there is still limited knowledge of the specific biomechanics that distinguish them from traditional resistance training (TRT) methods. The aim of this study is to compare the serial data of force, velocity, and displacement over time in half-squats performed with both devices when the intensity is based on the concentric mean propulsive velocity (MPV). A total of 20 experienced subjects completed 3 sets of 6 half-squats using both RID and TRT. To ensure a similar load intensity, the concentric phase was matched according to the MPV. Measurements of vertical ground reaction force (vGRF), velocity, and displacement were taken for each repetition of the half-squat. The results showed that TRT exhibited a higher vGRF than RID during 0-57% of the concentric phase but a lower vGRF during 74-93% (p < 0.001). Eccentric vGRF was also higher for TRT throughout much of the eccentric phase (0-13%, 38-54%, and 68-100%, p < 0.001). Rotary inertial device demonstrated faster vertical velocity than TRT during 31-52% of the concentric phase and 1-40% of the eccentric phase (p < 0.001). However, during the latter part of the concentric phase (72-99%), TRT exhibited faster vertical velocity compared with RID. In addition, TRT resulted in a higher vertical position than RID at the end (67-100%) of the concentric phase (p = 0.036). Coaches should be aware of these biomechanical differences when prescribing resistance training with RID or TRT, as even with similar loads, distinct patterns in vGRF and velocity over time can lead to different effects on the athlete.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Can the Variance in DP World Tour Golfers' Drive Distance be Predicted From Kinetic Variables During a Countermovement Jump and Isometric Mid-Thigh Pull?","authors":"Tara N Bage, Chris Bishop, Daniel Coughlan, Jack E T Wells","doi":"10.1519/JSC.0000000000005079","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005079","url":null,"abstract":"<p><strong>Abstract: </strong>Bage, TN, Bishop, C, Coughlan, D, and Wells, JET. Can the variance in DP World Tour Golfers' drive distance be predicted from kinetic variables during a countermovement jump and isometric mid-thigh pull? J Strength Cond Res XX(X): 000-000, 2024-In recent years, a growing body of research has investigated the relationships clubhead velocity has with kinetic variables during a countermovement jump (CMJ) and isometric mid-thigh pull (IMTP). However, to date, no research has investigated the relationships these kinetic variables have with real-world drive distance (DD) in elite DP World Tour golfers. The purpose of this investigation was to assess if CMJ positive impulse (PI), CMJ net impulse (NI), IMTP peak force (PF), force at 200 milliseconds, force at 250 milliseconds, and force at 300 milliseconds could predict the variance in elite DP World Tour golfers DD during a real-world tournament season. Twenty-five DP World Tour golfers performed CMJs and IMTPs on force plates in a real-world setting, with DD assessed using DP World Tour statistics. Hierarchical multiple regression analysis was used to assess if kinetic variables significantly predicted the variance in DP World Tour Golfers' DD. Statistical significance for this investigation was set at p ≤ 0.05 with effect size determined using the f2 statistic. The results of the investigation note that model 2 (CMJ PI and CMJ NI) was the best fit, significantly predicting (R2 = 0.279, p ≤ 0.05) the variance in DP World Tour Golfers' DD, which represented a large effect size (f2 = 0.39). These findings support the use of CMJ PI and CMJ NI when physically profiling elite golfers. In addition, strength and conditioning practitioners should consider utilizing modalities aimed at increasing CMJ impulse when working with golfers.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of 6-Week Vibration vs. Nonvibration Foam Rolling on Performance-Related Physical Fitness Parameters in Young Male Soccer Players: A Randomized Controlled Trial.","authors":"Erhan Secer, Derya Ozer Kaya","doi":"10.1519/JSC.0000000000005062","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005062","url":null,"abstract":"<p><strong>Abstract: </strong>Secer, E and Kaya, DO. Effects of 6-week vibration vs. nonvibration foam rolling on performance-related physical fitness parameters in young male soccer players: A randomized controlled trial. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to examine the effects of 6-week vibration foam rolling (VFR) and nonvibration foam rolling (FR) on performance-related physical fitness parameters in young male soccer players. Thirty-six, volunteer, young, male soccer players (mean age: 15.55 ± 0.55 years) were randomly assigned into 3 groups: a VFR group (n = 12), a FR group (n = 12), and a control group (CG) (n = 12). The players in VFR and FR groups performed VFR or FR interventions thrice per week for 6 weeks (3 × 30 seconds for each muscle or body side). Testing measures included reaction time, assessed with the reaction time measuring device; agility, assessed with the t test; sprint, assessed with the 20-m sprint test; and anaerobic power, assessed with the Wingate anaerobic power test. Dominant lower-extremity reaction time improved in the VFR group when compared with the FR group {-1.93 seconds (95% confidence interval [CI]: -3.07 seconds/-0.78 seconds)} and CG [-2.05 seconds (95% CI: -3.43 seconds/-0.67 seconds)]. Agility improved in the VFR and FR groups when compared with the CG [-0.90 seconds (95% CI: -1.26 seconds/-0.53 seconds), -0.53 seconds (95% CI: -0.95 seconds/-0.11 seconds), respectively]. Sprint improved in the VFR and FR groups when compared with the CG [-0.13 seconds (95% CI: -0.18 seconds/-0.07 seconds), -0.14 seconds (95% CI: -0.21 seconds/-0.06 seconds), respectively]. In conclusion, both 6-week VFR and FR increased agility and sprint performances. Vibration foam rolling is more effective than FR for improving lower-extremity reaction time. Vibration foam rolling and FR could be relevant options for strength and conditioning coaches to improve the physical performance of soccer players.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intensity of National Collegiate Athletics Association Division I Women's Soccer Regular Season Games.","authors":"Mario Norberto Sevilio De Oliveira Junior, Victor Geovani Soares de Sousa, Jefferson Fernando Coelho Rodrigues Junior, Nilo César Ramos, Jason Cholewa","doi":"10.1519/JSC.0000000000005053","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005053","url":null,"abstract":"<p><strong>Abstract: </strong>Sevilio De Oliveira Junior, MN, Soares de Sousa, VG, Coelho Rodrigues, JF, Ramos, NC, and Cholewa, J. Intensity of National Collegiate Athletics Association Division I women's soccer regular season games. J Strength Cond Res XX(X): 000-000, 2024-This study assessed the intensity of National Collegiate Athletics Association Division I women's soccer regular season games. Thirteen regular season games of one team (18 subjects) were analyzed. Data were collected on average intensity, accumulated time per heart rate (HR) zone, and HR behavior throughout each game. The HR zones adopted were as follows: Z1 = 50-59%, Z2 = 60-69%, Z3 = 70-79%, Z = 80-89%, and Z5 = 90-100% of maximum HR (HRmax). One-way analysis of variance (ANOVA) with repeated measures was performed for comparisons between games, by time range, and by HR zone. Two-way ANOVA with repeated measures compared average intensity of each game and high- and low-intensity zones between the first and second half (p ≤ 0.05). Average intensity of games was 89.08 ± 1.42% of HRmax, with minimum values of 67.12 ± 2.71% and maximum of 97.66 ± 0.98%, corresponding to 176 ± 2.13, 132.88 ± 5.50, and 193.66 ± 1.40 b·min-1, respectively. There was no significant difference in intensity between games (p = 0.09). Players spent more time in high-intensity zones Z5 and Z4. The average time in Z5 was 33 minutes 03 seconds ± 2 minutes 45 seconds and in Z4 was 18 minutes 24 seconds ± 2 minutes 34 seconds (p = 0.252). No significant differences were found in intensity comparisons between first and second half (p = 0.32) and 15-minute periods (p = 0.25). The intensity of games was high and constant throughout the 90 minutes in all games. Heart rate monitoring and planned substitutions during matches and training that focus on intermittent high-intensity activities and recovery, such as cold-water immersion may optimize match performance and prevent injuries.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative Analysis of Elbow Flexor Morphology, Physiology, and Performance Between Arm Wrestlers and Strength-Trained Athletes.","authors":"Francesco Coletta, Leonardo Cesanelli, Sigitas Kamandulis, Daniele Conte","doi":"10.1519/JSC.0000000000005071","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005071","url":null,"abstract":"<p><strong>Abstract: </strong>Coletta, F, Cesanelli, L, Kamandulis, S, and Conte, D. Comparative analysis of elbow flexor morphology, physiology, and performance between arm wrestlers and strength-trained athletes. J Strength Cond Res XX(X): 000-000, 2024-This study aims to compare the morphological, performance, and physiological characteristics of the elbow flexors between arm wrestlers and strength-trained athletes. Nine national and international level arm wrestlers (age = 30.5 ± 7.7 years, body mass = 89.4 ± 7.5 kg, stature = 183 ± 7.3 cm, strength training experience = 12.7 ± 8.6 years, arm wrestling training experience = 4.8 ± 2 years) and 9 strength-trained athletes (age = 28.6 ± 4.6 years, body mass = 88.2 ± 15.4 kg, stature = 179.4 ± 5.8 cm, strength training experience = 11.3 ± 8 years) voluntarily participated in the study. Arm and forearm circumferences of the dominant upper limb were measured to assess the anthropometric characteristics. Moreover, morphological evaluations of the biceps brachii muscle and distal tendon thickness were conducted using ultrasound. Peak torque (PT) and rate of force development (RFD) were assessed using 2 elbow flexion maximally voluntary isometric contraction tests (test-1: 3 × 3 seconds; test-2: 3 × 20 seconds). During test-2, biceps brachii oxygenation levels were measured using near-infrared spectroscopy. Arm wrestlers exhibited greater forearm hypertrophy compared with strength-trained athletes (p = 0.005; effect size [ES] = 1.54; large), whereas no differences (p > 0.05) were found in arm circumference and biceps brachii muscle and tendon thickness (normalized by muscle thickness). In addition, arm wrestlers showed higher PT in both tests (p < 0.05; ES = moderate-to-large) and higher RFD only in test-1 (p < 0.005). Finally, a greater reduction in muscle oxygenation levels (p = 0.025; ES = 0.277; moderate) was found compared with strength-trained athletes. This study provides insights of the arm wrestlers' physiological and performance characteristics allowing coaches to design appropriate training sessions in this unique sport.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Countermovement Jump Inefficiency Is Mostly Independent of Quadriceps Weakness in Athletes Returning to Sport After Anterior Cruciate Ligament Reconstruction.","authors":"Karl F Orishimo, Takumi Fukunaga, Ian J Kremenic, Smita Rao, Richard Magill, Wen K Ling, Malachy P McHugh, Stephen J Nicholas","doi":"10.1519/JSC.0000000000005066","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005066","url":null,"abstract":"<p><strong>Abstract: </strong>Orishimo, KF, Fukunaga, T, Kremenic, IJ, Rao, S, Magill, R, Ling, WK, McHugh, MP, and Nicholas, SJ. Countermovement jump inefficiency is mostly independent of quadriceps weakness in athletes returning to sport after anterior cruciate ligament reconstruction. J Strength Cond Res XX(X): 000-000, 2024-After anterior cruciate ligament reconstruction (ACLR), comparing ground reaction force (GRF) metrics during countermovement jumps (CMJs) and isokinetic quadriceps strength testing may aid in return-to-sport decision-making. The purpose of this study was to compare asymmetries in GRF metrics during bilateral and unilateral CMJs and asymmetries in quadriceps strength between patients after ACLR and healthy athletes. Twenty-two patients who had undergone ACLR and 12 healthy athletes performed isokinetic tests of quadriceps strength and maximal-effort bilateral and unilateral CMJs on force plates. Countermovement jumps force and isokinetic measurements were compared using repeated-measures analysis of variance. Associations between asymmetries in CMJ metrics and isokinetics were assessed using correlation analysis. In the patients, significant asymmetries in knee extension strength were found (24.5% at 60 °·s-1, 13% at 180 °·s-1). In addition, asymmetries were found in 4 of 6 GRF metrics during bilateral CMJs and in 10 of 15 metrics during unilateral CMJs. The control group showed no significant asymmetries in quadriceps strength or CMJ GRF metrics. Asymmetry in knee extension strength was not correlated with any bilateral CMJ asymmetries and only 2 unilateral CMJ asymmetries. Asymmetry in knee extension power was correlated with 3 bilateral CMJ asymmetries and 3 unilateral CMJ asymmetries. A comparison of GRF profiles revealed functional deficits on the involved side of the patients during both CMJs, indicating difficulty with stretch-shortening cycle function. Asymmetries were partially explained by deficits in quadriceps power but mostly independent of quadriceps weakness. Return-to-sport assessments after ACLR should include the assessment of the biomechanical efficiency of lower extremity stretch-shortening cycle function.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hamstring Muscle Stiffness During Isometric Contractions Until Task Failure in Footballers With and Without Injury History.","authors":"Antonio Martínez-Serrano, Régis Radaelli, Tomás Trindade de Freitas, Pedro Emilio Alcaraz, Sandro Remo Freitas","doi":"10.1519/JSC.0000000000005061","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005061","url":null,"abstract":"<p><strong>Abstract: </strong>Martínez-Serrano, A, Radaelli, R, Trindade de Freitas, T, Alcaraz, PE, and Freitas, SR. Hamstring muscle stiffness during isometric contractions until task failure in footballers with and without injury history. J Strength Cond Res XX(X): 000-000, 2024-Despite various proposed prevention strategies, the incidence of hamstring injuries in modern soccer is still elevated. Recent research has focused on exploring how muscle tissue stiffness behaves under fatigue conditions as a potential risk factor. This study aimed to examine the active stiffness of biceps femoris long head (BFlh) and semitendinosus (ST) muscles using ultrasound-based shear wave elastography (SWE) during a knee flexors' submaximal contraction until exhaustion in highly trained national-level male footballers, comparing previously injured and noninjured limbs. A case-control study was performed including 94 highly trained male footballers. Using SWE, the passive and active stiffness of the BFlh and ST were assessed at rest and during a knee flexors' submaximal isometric contraction at 40% of maximal voluntary isometric contraction (MVIC) until exhaustion. Differences in stiffness patterns between previously injured and noninjured limbs were analyzed, along with passive muscle stiffness, knee flexors' MVIC, and endurance capacity. No statistically significant differences in the active stiffness of BFlh and ST between previously injured and noninjured limbs throughout the contraction task were found (p > 0.05; 0-100% contraction time). Similarly, there were no statistically significant differences in BFlh (mean difference [mean diff.] = 0.2 kPa; p > 0.05) and ST (mean diff. = 0.9 kPa; p > 0.05) passive stiffness, knee flexors' MVIC (mean diff. = -8.5 Nm; p > 0.05), or time to exhaustion (mean diff. = 6.95 seconds; p > 0.05). Load-sharing between the BFlh and ST did not change significantly throughout the contraction (p > 0.05; 0-100% contraction time). These results suggest that players with a history of hamstring injuries may retain similar mechanical properties and coordination strategies as noninjured players.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Psychophysiologic Stress and Salivary Cortisol and Alpha-Amylase Awakening Responses to Cross-Country Running Competitions in National-Level Female Athletes.","authors":"Mustafa Aydemir, Yücel Makaracı, Bahattin Avcı, Yeşim Civil Ürkmez, Harry P Cintineo","doi":"10.1519/JSC.0000000000005055","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005055","url":null,"abstract":"<p><strong>Abstract: </strong>Aydemir, M, Makaracı, Y, Avcı, B, Ürkmez, YC, and Cintineo, HP. The psychophysiologic stress and salivary cortisol and alpha-amylase awakening responses to cross-country running competitions in national-level female athletes. J Strength Cond Res XX(X): 000-000, 2024-Cross-country running, characterized by diverse terrains and environmental conditions, primarily emphasizes individual performance, though team-oriented strategies are also used. This study aimed to examine psychophysiologic stress, anxiety, and race performance of elite female athletes during national cross-country running competitions. Twelve elite-level female cross-country runners were recruited to undergo psychophysiologic state using salivary cortisol and alpha-amylase levels (pre- and postrace) across 2 consecutive rounds of varying difficulty and significance (round 1 and final round). In addition, cortisol and alpha-amylase awakening responses (CAR and AAAR), and state anxiety (State and Trait Anxiety Inventory-I) were assessed on both precompetition and competition days during each round. The findings revealed significant increases in precompetition day AAAR, pre- and postrace cortisol, and postrace alpha-amylase levels in the final round compared with those in round 1 (p < 0.05). Mean race time was also faster in the final round than in round 1 (p < 0.05). Pre- and postrace cortisol levels were correlated with race time in round 1 (r = 0.554; r = 0.594), but not in the final round (p > 0.05). Increased cortisol emerged as a potential indicator of race difficulty and predictors of success in cross-country running. Coaches and athletes may benefit from monitoring cortisol levels to optimize performance during competitions with fluctuating conditions. Further research using saliva analysis as a noninvasive tool for assessing psychophysiologic parameters surrounding competition is warranted in larger samples across various endurance sports, though the data presented here provide a unique view of these responses.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physical and Match Characteristics of English Elite Academy Soccer Players: Differences Between Age Groups.","authors":"Brent Dickinson, Paul A Jones, Paul Comfort","doi":"10.1519/JSC.0000000000005065","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005065","url":null,"abstract":"<p><strong>Abstract: </strong>Dickinson, B, Jones, P, and Comfort, P. Physical and match characteristics of English elite academy soccer players: differences between age groups. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to evaluate physical and match characteristics of elite academy soccer players and determine differences between age groups. Sixty elite academy soccer players, including u15 (Subject: N = 15; age: 14.64 ± 0.25 years; mass: 59.88 ± 9.12 kg; height: 171.0 ± 6.7 cm), u16 (Subject: N = 15; age: 15.42 ± 0.36 years; mass: 65.11 ± 8.70 kg; height: 175.0 ± 7.2 cm), u18 (Subject: N = 15; age: 17.00 ± 1.00 years; mass: 72.85 ± 7.43 kg; height: 179.0 ± 6.4 cm), and u23 (Subject: N = 15; age: 19.60 ± 0.85 years; mass: 77.47 ± 7.03 kg; height: 181.0 ± 7.7 cm) participated in the study. Significant differences were seen in anthropometrics and maturation (p ≤ 0.031), absolute eccentric hamstring strength (p ≤ 0.033), absolute isometric mid-thigh pull performances ([IMTPs] p ≤ 0.026), jump height and reactive strength index from the 10-5 reactive jump tests (p ≤ 0.015), most countermovement jump variables (p ≤ 0.040), and the 30-15IFT (p ≤ 0.012), with better performances in older age groups. Absolute and relative (i.e., divided by time) match characteristics were significantly greater (p ≤ 0.038) in older age groups compared with younger age groups. Results indicate that older, more mature players demonstrate better performance in eccentric hamstring strength and IMTP peak force, based on absolute measures; however, the differences were negated when ratio scaled (i.e., divided by body mass). Strength training practices need to be improved to ensure that strength increases exceed those expected with increases in mass associated with maturation.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding the Context in Which Australian Footballers Sprint During Match-Play.","authors":"Ruby Guppy, Minh Huynh, Charlie Davids, Matthew C Varley","doi":"10.1519/JSC.0000000000005047","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005047","url":null,"abstract":"<p><strong>Abstract: </strong>Guppy, R, Huynh, M, Davids, C, and Varley, MC. Understanding the context in which Australian footballers sprint during match-play. J Strength Cond Res XX(X): 000-000, 2024-The aim of this study was to identify and describe the context in which Australian footballers perform sprint efforts during match-play. A secondary aim was to identify if different contextual factors influenced sprint occurrence within each position. A total of 4,224 sprint efforts (≥7.0 m·s-1) were analyzed from 37 elite Australian football players during the 2019 competitive season (21 matches). Players performed a median of 9 sprints per game (range: 0 to 29), with the median sprint distance being 13.4 m (range: 3.5-94.3 m), a median duration of 1.7 seconds (range: 0.5-12.7 seconds), and a median maximal speed per sprint of 7.54 m·s-1 (range: 7.02-9.61 m·s-1). Sprint efforts were coded for the following contextual factors: phase of play, player possession, player action, and the start and end field location. Of all sprint efforts, 39.7 and 36.9% occurred during the defensive and offensive phases, respectively. Most sprints (90.6%) were performed without the player having possession of the ball. Forwards performed the greatest proportion of sprints to create space (25.4%), backs to man an opponent (23.1%), midfielders to follow play (17.4%), and rucks to be first to the ball with pressure (22.2%). The context in which Australian football players perform sprints during matches will differ based on their position. This information can be used to design specific sprint training drills. Practitioners can use the methods outlined in this study to analyze the contextual factors within their own club and adjust training programs accordingly.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}