ECSS Paris 2023: OP-AP26
INTRODUCTION: In soccer, muscular strength is a determinant factor of performance. Stronger athletes may benefit from high-velocity-oriented strength training aimed at shifting the high-velocity region of the force–velocity curve, whereas weaker athletes may require a greater emphasis on maximal strength development to shift upward the entire force-velocity profile. The purpose of the study was to investigate the effects of strength-level-based organization of strength and power training on neuromuscular performance in youth soccer players. METHODS: Twenty-six male U16–U17 high-level youth soccer players completed baseline squat one-repetition maximum (1RM) testing and were divided into a stronger (SG, n=12) and a weaker group (WG, n=14). Over a 12-week in-season period, both groups performed one complex training session combining heavy resistance exercises with plyometric or ballistic exercises, whereas SG completed an additional power training session and WG an additional heavy strength session. Pre- and post-measurements included body composition, squat-1RM strength, leg extension isometric peak torque (IPT) and rate of torque development (RTD), countermovement jump (CMJ), drop jump (DJ), linear speed, repeated sprint ability (RSA), agility, shot velocity, and GPS-derived running metrics including top speed, maximal acceleration-deceleration, and aerobic capacity. A two-way repeated measures ANOVA (group x time) was used for the determination of pre- and post-differences. RESULTS: Both groups significantly improved the percentage of body fat (SG: -2.6%, p=0.01; WG: -2.4%, p=0.001) and lean mass (SG: 3.3%, p=0.005; WG: 4.35%, p=0.01). Squat 1RM strength relative to mass increased significantly in both groups (SG: 18.2%, p=0.001; WG: 27.19%, p=0.001). IPT relative to mass (SG: 10.3%, p=0.021; WG: 2.8%, p=0.03) and RTD increased for both groups (p<0.05). CMJ (SG: 5.7%, p=0.01; WG: 6%, p=0.05) and DJ reactive strength index increased in both groups (SG: 25.1%, p=0.004; WG: 26.2%, p=0.01). Linear sprint improved only in SG (30m: -1.3%, p=0.042), while RSA total time (SG: -2.7%, p=0.002; WG: -3.4%, p=0.01) and best time trial (SG: -2.4%, p=0.002; WG: -3.6%, p=0.01) improved for both groups. Shot velocity increased in both groups (SG: 8%, p=0.03; WG: 5.9%, p=0.01) while both groups increased top speed (SG: 3.2%, p=0.031; WG: 3.45%, p=0.014), maximal acceleration (SG: 7.3%, p=0.028; WG: 6.3%, p=0.01), and deceleration (SG: 7.7%, p=0.045; WG: 16.1%, p=0.003). Aerobic capacity significantly increased for both groups (SG: 1.6%, p=0.033; WG: 1.3%, p=0.047). CONCLUSION: Organizing the in-season strength and power training according to the athletes’ relative strength level is an effective strategy to enhance neuromuscular and physical performance in high-level youth soccer players. Strength and conditioning practitioners may consider allocating additional weekly training volume toward maximal strength development in weaker youth players and toward velocity-oriented power training in stronger players.
Read CV Andreas Kyriacou RossiECSS Paris 2023: OP-AP26
INTRODUCTION: Resistance training is considered safe for children and essential for youth athletes. However, valid tests for assessing strength levels in this population under field conditions remain limited. While the isometric mid-thigh pull or maximum number of pull-ups are promising tools for assessing knee-hip-extension and upper-body pulling strength, valid tests for assessing upper-body pushing strength are lacking. Embedded in a three-stage project, we introduce the upper-body isometric squeeze test (IST) as a novel and efficient field test to close this gap. METHODS: In a preceding investigation we established a high criterion validity between IST and bench press (BP) performance in strength training experienced adults (overall r=0.93, n=30; men r=0.88, n=15, 10.5 years strength training experience; women r=0.77, n=15, 9.1 years experience). To assess if this correlation remains stable in a younger cohort, we recruited 44 youth athletes with initial strength training experience (n=24 boys, 15.4±1.4 years old; n=20 girls, 14.4±1.6 years old) from regional performance development programmes in four different sports. Self-reported BP experience was 2.2±1.0 years in the boys and 1.7±0.8 years in the girls. After a standardised warm up, the participants completed a 1-to-5-repetition maximum BP protocol (RMP) and IST in a randomized order during one testing session. IST required a 3-second bilateral compression of a mobile dynamometer (DynaMo Plus, VALD, Brisbane, Australia) in front of the chest while lying in a supine position. BP performance was established using an estimated 1-repetiton-maximum (1RM) derived from the RMP. Criterion validity was assessed using Pearson correlation between BP 1RM and IST peak force. RESULTS: Mean BP 1RM was 74.7±18.5kg for the boys and 49.5±15.0kg for the girls, mean IST peak force was 458.0±102.5N and 322.2±69.2N respectively. Criterion validity for the whole cohort was high (r=0,79), for the boys moderate (r=0.64) and higher again for the girls (r=0.74). CONCLUSION: These findings indicate that IST can be considered as a valid proxy for maximal upper-body pushing strength. From our previous work we can conclude that general and/or strength-specific training experience might affect the criterion validation, suggesting to explore a more substantial familiarisation than we currently applied. By the same token, we are also still investigating why especially some boys (in contrast to the men in the previous study) struggled with the IST. However, the general ease of use of IST in its current form remains unmatched while still upholding a sufficient validity for a field test. Thus, we plan to investigate in a next step the reliability of IST in even younger youth athletes with limited to no (barbell-based) strength training experience.
Read CV Nikolai BöhlkeECSS Paris 2023: OP-AP26
INTRODUCTION: Driving distance and club head speed (CHS) are key determinants of elite golf performance, yet evaluations of controlled strength and power training interventions in elite-level golfers, particularly females, remain scarce. We examined the effects of 16 weeks of strength and power training on launch monitor-derived golf swing performance and mechanical muscle function in elite male and female golfers. METHODS: Twenty-nine elite-level golfers (15 female, 14 male) completed a 16-week strength and power training program (four sessions per week), while 11 golfers served as controls by continuing their habitual training routines. Pre- and post-intervention testing included launch monitor-derived driver and 6-iron performance (CHS, ball speed, carry distance, total distance) and a physical test battery comprising countermovement jump (CMJ), isometric mid-thigh pull (IMTP), isometric bench press (IBP), and maximal trunk rotation peak power. Training effects were evaluated using linear mixed models. Standardized effects were calculated as Hedges g with 95% confidence intervals (CI). RESULTS: Significant group-by-time interactions were observed for all driver performance outcomes in both male and female golfers. Driver CHS increased by ~4% in the intervention group in both females and males (p<0.001; females g = 2.23 [95% CI: 0.98, 3.47]; males g = 1.62 [95% CI: 0.53, 2.72]), with similar effects for ball speed and distance outcomes, and smaller but consistent improvements observed for 6-iron outcomes. Strength and power measures improved across multiple tests in the intervention group, while no changes were observed in controls. In males, the largest improvements were observed in IMTP peak force (+10.6%; p<0.001, g = 2.04 [95% CI: 0.88, 3.21]) and trunk rotation peak power (+16.6%; p<0.001, g = 1.90 [95% CI: 0.76, 3.04]), whereas females demonstrated particularly pronounced increases in IBP peak force (+6.6%; p<0.001, g = 1.95 [95% CI: 0.76, 3.15]). CONCLUSION: Sixteen weeks of strength and power training resulted in substantial improvements in golf swing performance and mechanical muscle function in elite male and female golfers. Swing performance improvements were comparable between sexes, despite sex-specific adaptations across measures of muscle strength and power were evident.
Read CV Per AagaardECSS Paris 2023: OP-AP26