https://hdl.handle.net/20.500.12412/2476 2026-05-06T04:45:07Z https://hdl.handle.net/20.500.12412/7238 Eccentric-concentric Ratio: A Key Factor for Defining Strength Training in Soccer Nuñez, Francisco Javier; de Hoyo, Moisés; Muñoz-López, Alejandro; Sañudo, Borja; Otero-Esquina, Carlos; Sánchez, Hugo; Gonzalo-Skok, Oliver The aims of this study were to analyse the effect of chronic strength training over concentric power (CON), eccentric power (ECC), ECC/CON ratio, and 20 m linear sprint performance in elite young soccer players. Twenty young elite Spanish soccer players were assigned to an experimental group (CPG) which performed a front-step exercise using a conical pulley, 2–3 sets of 6 repetitions each leg, during 9 weeks (CPG, n = 10) in addition to its usual strength training, or to a control group (CG, n = 10). The improvements in the ECC mean power (36 %, ES = 1.61), and ECC / CON ratio (17 %, ES = 1.77) were substantially greater in the CPG than in the CG while the CON mean power (16 %, ES = 0.83) was substantially greater in the CG than in the CPG. The sprinting time for 10 m (2.8 %, ES = 0.78) and the 10 m flying time between 10–20 m (1.72 %, ES = 0.41) were substantially enhanced in CPG and CG respectively. To be efficient when defining a functional strength training and performance increments using an inertial device, the mean power output need to be measured during the CON and ECC phases and an analysis of the ECC / CON ratio should be included. 2019-08-21T00:00:00Z https://hdl.handle.net/20.500.12412/7228 Reliability, responsiveness, & construct validity of the V-cut test in football players Gonzalo-Skok, Oliver The present study aimed to assess the reliability, responsiveness, and age-related and competitive level differences of a 25-m change of direction (COD) maneuver (V-cut test) in football players. Two-hundred and eighty-nine male football players performed the V-cut test. Thirty-four players underwent the test on two occasions, separated by 5-7 days, to assess test-retest reliability. Eighty-six young players performed the V-cut test three times, separated by 12 weeks, to analyze responsiveness. Finally, 89 young players of different ages (U-15 to U-20) and 80 adult players of different competitive levels performed the V-cut test several times throughout the season to examine between-group differences. Reliability scores showed a high intraclass correlation coefficient ((ICC)=0.94) and a low coefficient of variation ((CV)=0.8%). The responsiveness was dependent on the maturity status, showing a positive response in those players who were pre- (short-term p < 0.05) or post-PHV (short- and long-term p < 0.05), though PHV did not exceed minimal detectable change. Age-related (Effect size [ES]:0.93-5.68) and competitive-level differences (ES: 0.57-1.96) analysis reported better V-cut test performance as age and competitive-level increased in football players. The V-cut test is reliable for assessing COD ability and can be used to monitor COD ability depending on maturity, allowing it to differentiate between players of different ages and levels. 2026-04-17T00:00:00Z https://hdl.handle.net/20.500.12412/7191 Contextual factors affect match sprinting demands and effective playing time in Spanish professional football Galiano, Carlos; Gómez-Piqueras, Pedro; Piernas, Alberto; Gonzalo-Skok, Oliver Sprinting demands are a key factor in football. While effective playing time seems to affect them, there is a lack of information related to contextual factors. The present study aimed to compare effective playing time according to the level of the opponent and competition division, and to compare sprinting distance and the number of sprints, accounting for effective playing time, in relation to contextual variables such as match location, match final outcome, and match difficulty across the First and Second Spanish Divisions. All matches from the 2021/22 season in the First (n = 380) and the Second (n = 462) Spanish Divisions were analysed. Two variables were used to determine the physical performance: the total distance covered at speeds above 24 km/h and the number of efforts made at speeds above 24 km/h relative to effective playing time (m · min−1 and sprints · min−1). Difficulty-4 matches (teams qualified 1st to 5th) exhibited higher effective playing time than all other difficulty levels in both the First (p < 0.001; ES > 0.71) and the Second Division (p < 0.004; ES > 0.30). The sprint demands showed a significant effect of difficulty (p < 0.001), with lower sprint activity recorded in level-4 matches, a significant effect of match outcome (p < 0.001), with winning teams performing a greater sprint activity and a significant effect of location (p < 0.001), with teams performing a greater sprint activity in home matches. Effective playing time and sprinting demands show variation according to when top-tier teams (1st to 5th) are involved. Finally, winning and playing at home may be related to slightly superior sprinting demands. 2026-04-13T00:00:00Z https://hdl.handle.net/20.500.12412/7113 Assessing the Reliability and Validity of Agility Testing in Team Sports: A Systematic Review Morral-Yepes, Mónica; Moras, Gerard; Bishop, Chris; Gonzalo-Skok, Oliver The aims of this systematic review were to (a) examine the reliability of the reactive agility tests and (b) analyze the discriminatory validity of the agility tests. A literature search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We explored PubMed, SPORTDiscus, and Cochrane Plus databases looking for articles about agility in team sports. After filtering for article relevance, only 42 studies met the inclusion criteria; 37 of which assessed the reliability of agility tests and 22 assessing their validity. Reliability showed a high intraclass correlation coefficient (ICC) in almost all studies (range 0.79-0.99) with the exception of 2 studies. In addition, other studies also assessed the reliability of decision time (ICC = 0.95), movement time (ICC = 0.92), and decision accuracy (ICC = 0.74-0.93), all of which exhibited acceptable reliability. Furthermore, these data show high discriminatory validity, with higher performance level players being faster than lower performance level players (mean = 6.4%, range = 2.1-25.3%), with a faster decision time (mean = 23.2%, range = 10.2-48.0%) with the exception of 1 study, and better decision accuracy (mean = 9.3%, range = 2.5-21.0%). Thus, it can be concluded that reactive agility tests show good reliability and discriminatory validity. However, most agility tests occur in simple contexts whereby only 2 possible responses are possible. Therefore, future research should consider creating more specific and complex environments that challenge the cognitive process of high-level athletes. 2022-07-01T00:00:00Z