Introduction: Muscular strength is an essential capacity for soccer players; however, the profile of this capacity has not yet been clearly established in young players. Objective: To compare muscular strength performance in the countermovement jump (CMJ) task and the presence of lower limb asymmetry among soccer athletes of the under 15 (U15), under 17 (U17) and under 20 (U20) categories, and between two teams of different competitive levels. Methods: One hundred and fifty one young soccer players of three different categories (U15, U17 and U20) from two teams in the Brazilian first and second divisions performed six vertical jumps in a system of two force plates. Ground reaction force (GRF) was used to calculate jump height and to obtain the variables Peak force (FMAX), Impulse (I) and Peak power (PMAX) with regard to body mass and the respective asymmetry values. Results: No differences were found in the performance and asymmetry variable between the categories (Jump height: p=0.23; FMAX: p=0.15; I: p=0.11; PMAX: p=0.32; FMAX asymmetry: p=0.21; I asymmetry: p=0.58; PMAX asymmetry: p=0.58). The first division club had higher muscle strength and asymmetry values than the second division club (Jump height: p<0.01; I: p<0.01; PMAX: p<0.01; FMAX asymmetry: p<0.01; I asymmetry: p<0.01; PMAX asymmetry: p<0.01), except for FMAX (p=0.63). No variable had an interaction effect (club x category). Conclusion: As categories progress, jump height, relative I, PMAX and FMAX values and their respective asymmetries are stable. The asymmetry and strength performance of the first division club were higher than that of the second division club, except for FMAX, indicating that the competitive level may influence strength performance and the development of asymmetry. Level of Evidence II; Diagnostic study – Investigating a diagnostic test.

This study aimed to measure the reliability of a test for measuring the strength and strength imbalance of the hip abductors and adductors, using isokinetic equipment adapted for isometric testing. Thirteen healthy, physically active male individuals took part in the research. Two unilateral isometric tests were undertaken using a load cell attached to an adapted abductor bench machine: a hip abduction test and hip adduction test. Tests consisted of two maximum voluntary isometric contractions made for six seconds with a break of one minute between each. The following dynamic variables were measured: maximum force, mean force, rate of force development for each limb (right and left), and the existence of asymmetries between the limbs. For statistical analysis, the t-test, intraclass correlation coefficient (ICC), and standard error of measurement (SEM) were applied. Results: The methodology utilized for the evaluation of the hip abductors and adductors did not show reliability in most of the parameters researched, with the ICC neither sufficient or low, and the retest performance higher than the test (p < 0.05). The applied test was not reliable for assessing strength and strength imbalances of hip abductors and adductors in most of the parameters investigated. These results indicate that the hip joints, more precisely, the abductor and adductor muscles, are complex structures to be assessed. They need to be previously familiarized with the proposed exercise, as their performance does not occur habitually. It is recommended to develop new tests in order to measure hip abduction and adduction strength adding a prior familiarization procedure.

Among traditional cardiovascular diseases (CVD) risk factors, obesity has become a major research target due to its epidemic prevalence¹ 1 GBD 2017 Risk Factor Collaborators. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2018;392(10159):1923-94. http://dx.doi.org/10.1016/S0140-6736(18)32225-6. PMid:30496105. http://dx.doi.org/10.1016/S0140-6736(18)... . Another independent risk factor for CVD is psychological stress² 2 Huang CJ, Webb HE, Zourdos MC, Acevedo EO. Cardiovascular reactivity, stress, and physical activity. Front Physiol. 2013;4:314. http://dx.doi.org/10.3389/fphys.2013.00314. PMid:24223557. http://dx.doi.org/10.3389/fphys.2013.003... . Acute mental stress tasks have been used as a laboratory models to examine cardiovascular response to psychological stress³ 3 Carroll D, Ginty AT, Der G, Hunt K, Benzeval M, Phillips AC. Increased blood pressure reactions to acute mental stress are associated with 16-year cardiovascular disease mortality. Psychophysiology. 2012;49(10):1444-8. http://dx.doi.org/10.1111/j.1469-8986.2012.01463.x. PMid:22958235. http://dx.doi.org/10.1111/j.1469-8986.20... 4 Steptoe A, Kivimaki M, Lowe G, Rumley A, Hamer M. Blood pressure and fibrinogen responses to mental stress as predictors of incident hypertension over an 8-year period. Ann Behav Med. 2016;50(6):898-906. http://dx.doi.org/10.1007/s12160-016-9817-5. PMid:27401000. http://dx.doi.org/10.1007/s12160-016-981... -⁵ 5 Carroll D, Phillips AC, Der G, Hunt K, Benzeval M. Blood pressure reactions to acute mental stress and future blood pressure status: data from the 12-year follow-up of the West of Scotland Study. Psychosom Med. 2011;73(9):737-42. http://dx.doi.org/10.1097/PSY.0b013e3182359808. PMid:22021460. http://dx.doi.org/10.1097/PSY.0b013e3182... . Evidence has suggested that the association between systolic blood pressure (SBP) reactivity to mental stress and increased risk for future cardiovascular events is independent of baseline BP values⁶ 6 Chida Y, Steptoe A. Greater cardiovascular responses to laboratory mental stress are associated with poor subsequent cardiovascular risk status: a meta-analysis of prospective evidence. Hypertension. 2010;55(4):1026-32. http://dx.doi.org/10.1161/HYPERTENSIONAHA.109.146621. PMid:20194301. http://dx.doi.org/10.1161/HYPERTENSIONAH... .

In combat sports, precise technique evaluation is crucial for performance optimization; however, traditional systems for evaluating kick performance are frequently unreasonably complicated and costly. This study offers a useful and accessible substitute by introducing a contact mat-based tool that measures the roundhouse kick’s execution time during both the attack and recovery phases and by demonstrating its reliability. The experimental sessions involved 16 male Shotokan karate athletes (age: 25.6 ± 7.1 years; height: 1.74 ± 0.05 m; body mass: 71.5 ± 8.7 kg; body fat percentage: 14.7 ± 6.7%; training experience: 11.0 ± 4.9 years). The protocol included four sessions, starting with a familiarization phase followed by three testing sessions (test, retest, and retest two), during which a standardized warm-up was performed along with the roundhouse kick test. The intraclass coefficient correlation (ICC) used indicated high reliability for the at-tack (ICC = 0.85, 95% CI [0.64, 0.94]), recovery (ICC = 0.89, 95% CI [0.75, 0.96]), and total time (ICC = 0.90, 95% CI [0.76, 0.96]). The Friedman test revealed no significant difference between testing sessions (p > 0.31), demonstrating high reliability and no significant differences between sessions. This study confirms the system as a simple and reliability tool for measuring roundhouse-kick timing in combat sports.

Purpose: This study aimed to compare internal load (IL) and external load (EL) variables between blocks of a game-based Rugby Sevens training session.Methods: A descriptive cross-sectional study design was employed. Twenty-eight professional athletes from the first division of the Brazilian national championship were monitored during a game-based training session, which consisted of varying durations of ball-in-play blocks. The training session comprised 4 blocks of 1 min, 2 blocks of 2 min, and 1 block of 3 min of ball-in-play, with 1-min intervals between blocks of the same duration and 2-min intervals between blocks of different durations.Results: A reduction in EL was reported during longer bouts of ball-in-play. Specifically, a reduction was observed when comparing block 5 to block 1 (p = 0.021) and when comparing block 7 with blocks 1, 2, 3, 4, and 6 for distance per min. For accelerations and decelerations, blocks 5, 6, and 7 showed lower values than block 1 (p = 0.001 and p = 0.005, respectively). Block 4 showed an increase in rate of perceived exertion (RPE) values compared to blocks 1 (p = 0.010) and 2 (p = 0.004). Increased RPE values were also found in block 5 compared to block 1 (p = 0.001), as well as compared to blocks 2 (p = 0.001) and 3 (p = 0.002). RPE in block 7 was higher than in blocks 1, 2, 3, and 4 (p = 0.001).Conclusions: In summary, higher RPE values were reported across blocks, and IL appeared to be more volume-dependent.

Karate athletes strategically use lower-limb techniques in combat, with the roundhouse kick (mawashi geri) being highly effective in kumite. To quickly improve the technical performance before training or competitions, conditioning activities (CAs) are often utilized. Recently, Whole-Body Vibration (WBV) has emerged as a potential conditioning activity (CA). This study aimed to analyze the acute effects of WBV as a CA on the performance of the mawashi geri. The sample included sixteen male karate athletes. The study had a familiarization and two experimental sessions: one with WBV and the other without (NWBV), conducted randomly and counterbalanced, each preceded and followed by a mawashi geri assessment on a force platform. During the CA intervention, the participants performed four sets of isometric half-squats on a vibration platform at a frequency of 26 Hz and an amplitude of 4 mm in the WBV condition, while the platform was off in the NWBV condition. A significant reduction in the mawashi geri attack phase time was observed under the WBV condition [pre: 0.31 ± 0.03 s; post: 0.30 ± 0.03 s] compared to the NWBV condition [pre: 0.31 ± 0.04 s; post: 0.32 ± 0.03 s] (p = 0.02). However, no differences were noted regarding the impact force or other kinetic variables between the conditions. Therefore, WBV did not increase the performance of the kinetic and kinematic variables of the mawashi geri in karate athletes, but it is possible that there is a positive effect on attack time, suggesting that further studies with different vibration protocol configurations would be beneficial.