ECSS Paris 2023: CP-AP28
INTRODUCTION: Strategies aiming to acutely enhance neuromuscular performance before competition are of increasing interest in elite football. Recent studies suggest that low volume power or strength training may induce a delayed positive effect on neuromuscular performance 24 to 48 hours later. However, there is limited evidence of the effectiveness of such protocols in an elite football setting. The aim of this study was to investigate the effects of a French-Contrast training session combined with football training on lower limp strength and power measures 24 hours later, in elite academy football players METHODS: Fifteen elite academy players of an elite U-16 football team completed two conditions in a randomized crossover design with: (1) a French-contrast priming session, followed by MD-1 football training (PRIME), and (2) MD-1 football training only (CONTROL). The French-contrast series included two rounds the following four exercises: maximal isometric squat exercise for 3 s (knee angle: 150o), six Pogo-jumps with +20% body weight, eight unloaded Pogo-jumps, five assisted jumps, A 3 min rest separated the two rounds. Neuromuscular performance was assessed before and 24 h after each session. Countermovement jump (CMJ), reactive strength index (RSI), maximal voluntary isometric half-squat force (MVIC), and rate of force development (RFD) were assessed and analyzed using repeated-measures ANOVA. Effect sizes for pairwise comparisons were obtained as Cohen’s d. RESULTS: Significant main effects were found in RSI for both time and condition (p = 0.016 and p < 0.001) with no significant time x condition interaction (p = 0.269). At baseline, RSI was 1.59 ± 0.29 and 1.65 ± 0.27 m/s in PRIME and CONTROL. Twenty-four hours later, the respective RSI values were 1.74 ± 0.32 and 1.90 ± 0.30 (d=0.44 between conditions). CMJ at baseline was similar in PRIME and CONTROL (34.9 ± 3.8 and 34.9 ± 3.7 cm) and remained unchanged 24 h later (34.9 ± 4.0 and 36.1 ± 3.8 cm), with no main effects or interaction. Cohens’ d for changes in CMJ were 0.02 and 0.31 in PRIME and CONTROL. MVIC showed no significant main effects or interaction (p = 0.81, 0.124 and 0.42, respectively), Baseline MVIC in PRIME and CONTROL was 2614 ± 270 and 2564 ± 331 N, while values 24 hours later were 2697 ± 315 and 2720 ± 362 N, respectively (d=0.27 and 0.43, respectively). The effect sizes for changes in RFD were very low in CONTROL and moderate in PRIME (0.47 and 0.62 for RFD 0-250 and 0-300 ms). CONCLUSION: The combination of resistance-based priming with football training did not lead to statistically significant improvements the neuromuscular variables measured 24 h later, with the exception of RSI, where a main effect of condition was found. However, this preliminary study indicates that there may be small but meaningful improvements in explosive strength 24 hours after the combination of French-contrast and football training, as suggested by effect sizes.
Read CV Nikos BalisECSS Paris 2023: CP-AP28
INTRODUCTION: In football, the optimisation of training, recovery and performance requires a comprehensive understanding of the acute responses to training load [1]. This study aimed to characterise the acute neuromuscular, metabolic and perceptual responses to an in-season training session in high-level youth football players. METHODS: Thirteen Italian Serie A youth academy players (age: 18.2 ± 0.6 years; height: 183.0 ± 6.3 cm; body mass: 75.1 ± 6.9 kg) were assessed before (pre) and after (post) a typical training session using neuromuscular performance tests (countermovement jump, CMJ, and isometric posterior chain test, IPC), metabolic markers (capillary blood samples) and perceptual measures (muscle soreness and fatigue using visual analogue scales). From the capillary blood samples, serum fractions were assessed via untargeted proton nuclear magnetic resonance metabolomics. Training loads (global navigation satellite system, heart rate, HR, and session rating of perceived exertion methods, sRPE) and energy intake (remote food photographic method) were quantified. Differences between pre- and post-training in neuromuscular and perceptual measures were analysed using paired t-tests and Hedge’s g (g) effect size. Metabolites were analysed using multivariate and univariate analyses to identify differences in the serum metabolome between pre- and post-training. RESULTS: The training session consisted of a 60-minute duration with moderate training loads (total distance: 5009 ± 440 m; high-speed running distance: 310 ± 49 m; accelerations: 53 ± 17 events; time > 85% HRmax: 8 ± 7 min; sRPE: 3.3 ± 0.7 au). The training demands induced significant reductions in CMJ eccentric peak force, concentric peak force and force at zero velocity at post-training (p < 0.05; g: small to moderate), whilst no significant changes were observed in other CMJ measures (p > 0.005, g: trivial to small). Similarly, no significant changes were observed in IPC peak force and torque (p > 0.005, g: trivial), perceptual fatigue (p = 0.947, g: trivial) and muscle soreness (p = 0.281, g: small). Of the 54 identified metabolites, 21 showed significant changes post-training (p < 0.05), with increased concentrations of lactate, alanine, isoleucine, tyrosine and 3-hydroxisobutyrate, and decreased abundances in 16 other metabolites related to amino acid and lipid metabolism. CONCLUSION: This study suggests that, although a moderate‑load training session elicited minimal perceptual fatigue and only small neuromuscular impairments, it provoked marked alterations in the serum metabolome, underscoring the need to monitor both neuromuscular and physiological load–response pathways to better inform training and recovery interventions in high-level youth academy football players. References: [1] Vanrenterghem et al. (2017), Sports Medicine
Read CV Alberto FranceschiECSS Paris 2023: CP-AP28
INTRODUCTION: The interference effect is a well-known concern among practitioners due to its potential negative impact on athletic performance. Although concurrent training does not appear to impair muscle hypertrophy, its effects on strength and power adaptations remain debated. Given that concurrent training is an integral component of the in-season weekly schedule in team sports, the purpose of this study was to compare an optimally structured concurrent training approach with a strength-only approach on key muscle power performance metrics in elite youth soccer players during the in-season period. METHODS: Forty-eight elite youth soccer players were allocated to concurrent training (CG, n=16), strength-only training (SG, n=16) or control groups (CONTR, n=16). The SG performed an in-season individualized strength training program once per week for six weeks. Load and exercise selection was based on players individual force–velocity profiles, aiming to reduce force–velocity imbalance and enhance muscle power performance. The CG followed the same strength program but additionally performed either a high-intensity interval session (2 × 5 min with 15 s running and 15 s passive recovery at 10% of anaerobic speed reserve) or sprint interval training (six all-out sprints over 30–50 m) immediately after strength training. The CONTR continued their regular strength, power and endurance training programs. GPS data were collected only in experimental groups. RESULTS: Following the intervention, both experimental groups demonstrated similar improvements in neuromuscular performance, whereas CONTR showed non-significant changes. Countermovement jump height increased by 9.2% in the CG and 6.9% in the SG (both p < 0.001). Isometric force during the squat exercise (knee angle: 125º – 135°) at 100 ms increased significantly in both the CG and SG (20% and 23%, p < 0.001), while no changes were observed in the CONTR. Also, sprint performance over 10 m improved by 1.9% in the CG (p < 0.01) and SG by 1.5% (p = 0.03) with no changes in CONTR. Aerobic fitness improved only in the CG, as shown by the reduction of heart rate responses during the submaximal Yo-Yo Intermittent Recovery Level 1 test (−10.2%; p < 0.001), compared with the SG (−2.7%; p < 0.02). Total weekly training distance was similar in both experimental groups (p > 0.05); however, the CG covered 17.4% greater high-speed running distance compared with the SG (p < 0.01). CONCLUSION: Concurrent training does not induce an interference effect on muscle power–related performance and acceleration in elite youth soccer players. The inclusion of low-volume, high-intensity endurance training improves aerobic performance, as reflected by heart rate responses during the submaximal YYIR1 test, without compromising neuromuscular development when strength training was individualized based on force–velocity imbalance.
Read CV Ilias-Iason PsarrasECSS Paris 2023: CP-AP28