Objective: This study aimed to compare the maximum and rapid force production of Spanish football players and explore the differences between age group and level of competition. Methods: A cross-sectional study was developed to evaluate the peak force (PF), relative PF, and rate of force development over 250 ms (RFD₀₋₂₅₀) during the isometric midthigh pull between groups of football players based on age group (senior vs junior) and level of competition (national vs regional). Using a portable isometric rig, 111 football players performed 2 isometric midthigh-pull trials on a force plate. Two-way analysis of variance with Bonferroni post hoc correction was applied, and statistical significance was set at P ≤ .05. The PF, relative PF, and RFD₀₋₂₅₀ 0, 25, 50, 75, and 100 percentiles were also calculated and descriptively reported, separated by age group and level of competition. Results: The analysis of variance revealed a significant main effect of the level of competition for the PF (P < .001), relative PF (P = .003), and RFD₀₋₂₅₀ (P < .001). There was a significant main effect of age group for the PF (P < .001). There was a significant interaction effect of the age group × level of competition for relative PF (P = .014). National players were stronger than regional players on the PF and RFD₀₋₂₅₀ (P < .001). Senior players were stronger than junior players for the PF (P < .001). Conclusions: Maximum and rapid force production are crucial for Spanish football players as they progress in both level of competition and age group. Practitioners should encourage young football players to prioritize strength development to improve their athletic performance.

The aim of this study was to explore the reliability and feasibility of the isometric mid-thigh pull (IMTP) and dynamic strength index (DSI) in semi-professional handball players (seventeen male and eighteen female). A cross-sectional design was used to determine the test-retest reliability of several kinetic metrics registered with a force plates. The peak force, peak relative force, rate of force development (RFD _{0-250 ms}), and impulse _{0-250 ms} were selected from the IMTP test, whereas the peak propulsive force was chosen from the countermovement jump test to obtain the DSI. The intraclass correlation coefficient (ICC), coefficient of variation (CV), standard error of the measurement (SEM) and smallest detectable difference (SDD) were calculated. A paired sample t-test was also performed. No significant differences were found between the testing sessions for all variables, except for peak propulsive force for all players (p = 0.036) and DSI for female players (p = 0.037). Reliability for all kinetic metrics was good to excellent (ICC = 0.78-0.97), with low variability (CV ≤ 8.64%), being the SEM scores lower than SDD. In conclusion, the IMTP test and DSI are highly reliable and feasible tools for assessing neuromuscular performance in semi-professional handball players.

Rugby players need muscular strength and power to meet the demands of the sport; therefore, a proper assessment of the performance in rugby players should include both variables. The purpose of this study was to examine the strength and power characteristics (SPC) during the squat (SQ) and bench press (BP) in national amateur rugby players and to analyze gender- and position-related differences. A total of 47 players (30 males and 17 females; age: 25.56 ± 1.14 and 23.16 ± 1.38 years, respectively) participated in the study. The one repetition-maximum (1-RM) and SPC in SQ and BP were obtained using a Smith Machine. Then, subjects performed one set of five repetitions on the SQ and BP against six relative loads (30–40–50–60–70–80% 1-RM) using a linear transducer. Differences between genders were found in 1-RM for maximal power, kilograms lifted at maximal power, maximal power, maximal strength and maximal speed in BP (p < 0.00) and 1-RM, kilograms lifted at maximal power, maximal power, maximal strength and maximal speed in SQ (p < 0.00). Comparisons between variables in SQ and BP present a significant relationship (p < 0.01) in SQ and BP 1-RM with kilograms lifted at maximal power (r = 0.86 and r = 0.84), maximal strength (r = 0.53 and r = 0.92) and maximal power (r = 0.76 and r = 0.93). This study confirms the importance of the SPC assessment for training prescription in rugby amateur players.

Background/Objectives: This longitudinal randomized controlled study aimed to evaluate the effects of an integrative neuromuscular training (INT) intervention on strength and speed measures in Spanish students across different age groups. Methods: A total of 121 students, aged 11–12 (G1) and 15–16 (G2), were randomly assigned to four groups: two experimental groups, G1exp (n = 30) and G2exp (n = 31), and two control groups, G1con (n = 30) and G2 (n = 30). Experimental groups participated in two 20 min INT sessions per week for four weeks, focusing on physical literacy (agility, coordination, balance, and speed) and a resistance training program, integrated into the first part of physical education classes (PEC). Results: Experimental groups showed significant improvements (p < 0.001) in lower-body power (G1exp: t = −7.04; d = −1.30; G2exp: t = −5.19; d = −0.91), upper-body power (G1exp: t = −5.94; d = −1.10; G2exp: t = −3.52; d = −0.62), abdominal endurance strength (G1exp: t = −9.72; d = −1.80; G2exp: t = −4.75; d = −0.84) and sprinting (G1exp: t = 5.22; d = 0.96; G2exp: t = 5.90; d = 1.04). A comparison by age groups revealed significantly greater improvements in upper-body power in G1 vs. G2 (t:−2.83; p = 0.02). Conclusions: A four-week INT program implemented at the start of PE classes can improve strength and sprint performance in youth across all ages. We recommend incorporating INT into the first part of physical education sessions to contribute to meeting the physical activity, well-being and conditioning needs of young people.

Objective: This study examined the effects of a short-duration plyometric training program during physical education on neuromuscular ballistic performance in youth. Methods: Thirty-two students were assigned to a control group (CG; n = 16; age: 16.76 ± 0.72 years; height: 1.66 ± 0.09 m; body mass: 61.38 ± 6.07 kg) or an experimental group (EG; n = 16; age: 16.56 ± 0.62 years; height: 1.69 ± 0.09 m; body mass: 61.90 ± 7.83 kg). Both groups completed pre- and post-intervention Countermovement Jump (CMJ) tests using force plates. Over a four-week period, the EG completed eight sessions. Both the EG and the CG participated in 40 min sessions incorporating speed games, directional changes, and agility exercises. Paired t-tests and Cohen’s d were used for analysis. Results: The EG showed significant improvements in jump height (p = 0.006, ES = 0.83), jump momentum (p = 0.008, ES = 0.80), and take-off velocity (p = 0.003, ES = 0.93), with a decrease in peak propulsive power (p = 0.01, ES = 0.77). In contrast, the CG exhibited declines in multiple metrics, including jump height, jump momentum, and take-off velocity. Conclusions: These findings suggest that integrating plyometric training into physical education classes can effectively enhance neuromuscular performance in youth. Implementing structured training protocols within school programs may optimize strength, power, and movement efficiency, benefiting long-term athletic development.

Ischemic preconditioning (IPC) has shown positive effects in endurance-type sports among healthy young individuals; however, its effects in endurance-type exercises in older adults have not been explored. We aimed to examine the acute effects of a single session of IPC prior to an endurance-type exercise on cardiovascular- and physical-function-related parameters in sedentary older adults. A pilot study with a time-series design was carried out. Nine participants were enrolled consecutively in the following intervention groups: (i) SHAM (sham IPC + walking) and (ii) IPC (IPC + walking) groups. The main outcomes were resting systolic (SBP) and diastolic (DBP) blood pressure, heart rate (HR), peripheral oxygen saturation (SpO₂), maximum isometric voluntary contraction (MIVC), endurance performance, and perceived fatigue. After the intervention, the IPC group showed a significant reduction in SBP, whereas SpO₂ decreased in the SHAM group. The IPC group maintained quadriceps MIVC levels, whereas these levels dropped in the SHAM group. No changes in DBP, resting HR, endurance, or fatigue in any group were observed. These findings are of interest for the promotion of cardiovascular and physical health in older people.