RELATIONSHIP BETWEEN EXTERNAL LOAD AND DIFFERENCES IN COUNTERMOVEMENT JUMP IN AN OFFICIAL MATCH OF PROFESSIONAL FEMALE SOCCER PLAYERS.

The purpose of the present study was to correlate the external load of an official soccer match with the percent change in the countermovement jump variables in professional soccer players and to analyze the differences between moments (pre, immediately post and 24 hours post-match). The main findings were the correlations between the percentage of change in the CMJ variables and the external load very strong between JH1 with ACC4; JH2 with D23, HSR, ACC1 and DCC2; JT1 with ACC4; PP1 with ACC3; RFDB1 with ACC4; RPD1 and RPD2 with D7. On the other hand, differences were found in PF between pre and post, in PP between post and 24h, RFDB between pre and post. Through our results we conclude that the change in the vertical jump with countermovement is correlated with the external load performed during a match in professional players, so that the assessment of the mechanical variables of the jump on force platforms is a practical option to assess fatigue after a soccer match. An individual analysis is also necessary to know the intra-player differences because the group analysis is influenced by the external load

VERTICAL JUMP CHARACTERISTICS AND LOWER LIMBS MUSCULAR CONTRIBUTION IN CHILEAN VOLLEYBALL PLAYERS DURING THE COUNTER MOVEMENT JUMP (CMJ).

The purpose of this study was to determine and to compare characteristics of the lower limb extension musculature in Chilean indoor and beach volleyball players and the muscular contribution during the CMJ. The sample was composed by 13 subjects belonging to the Chilean elite beach and indoor volleyball. The subjects performed 3 CMJ jumps for average determination of the height of the jump, eccentric force development rate (TDFE), concentric force development rate (TDFC), power and lower limbs muscular contribution, evaluated using force platform and wireless electromyography (EMG). The results demonstrated a significant relationship between the height of the jump-TDFC and power-TDFC and Medial vasti muscle has obtained the most significant contribution during the CMJ in volleyball players

IT NECESSARY TO NORMALIZE JUMP TEST RESULTS TO ANTHROPOMETRIC PARAMETERS?

The purpose of the present study was to analyse the relationship of different normalization methods in the jump performance, obtained from a digital application (My Jump 2 ®). 189 young women made up the sample. Each of them had to perform three attempts of a bilateral countermovement jump (CMJ) in front of a mobile device. The jump height (JH) and power (P) were the main results, which were processed to normalize them. The JH was normalized to height (JH/H) and to leg length (JH/LL). P was normalized to body mass (RP), while force values were divided by the time of jump to get the Explosive Index of Strength (EIS). The results showed a good association and poor prediction between the variables JH and P, not so between JH and EIS, where no significant relationship was observed. However, a strong relationship was observed between JH / LL and RP (r = 0.801; r2 = 0.641; p KEYWORDS: Smartphone app, vertical jump, biomechanics

THE EFFECTS OF 21 DAYS HYPOXIA ON ELECTROMYOGRAPHIC ACTIVITY VARIATION IN ROWERS PRE AND POST-ALTITUDE.

The purpose of this study was to determine and to compare EMG characteristics of the vastus medial quadriceps in Chilean rowers in hypoxia. The sample was 11 Chilean elite rowers. The evaluation procedure consisted of every subject performing a maximal test of incremental ergospirometry intensity until fatigue. The EMG analysis was implemented when the sportsmen reached the VO2max intensity with wireless EMG. In the analysis, RMS EMG signals were utilized. The results showed a significant difference between EMG activity in normoxia pre-altitude and normoxia post-altitude after 21 days in hypoxia

Mechanical determinants of sprinting and change of direction in elite female field hockey players

Profile determination in field hockey is critical to determining athletes’ physical strengths and weaknesses, and is key in planning, programming, and monitoring training. This study pursued two primary objectives: (i) to provide descriptive data on sprinting, deceleration, and change of direction (COD) abilities and (ii) to elucidate the mechanical variables that influence sprint and COD performance in elite female field hockey players. Using radar and time-gate technology, we assessed performance and mechanical data from 30 m sprinting, deceleration, and COD tests for 26 elite female hockey players. A machine learning approach identified mechanical variables related to sprint and COD performance. Our findings offer a framework for athlete categorization and the design of performance-enhancing training strategies at the international level. Two pivotal mechanical variables—relative maximum horizontal force (F0) and maximum velocity (Vmax)—predominantly influence the times across all tested distances. However, the force–velocity profile (FVP) and horizontal deceleration do not influence the variance in the COD test outcomes. These insights can guide the design, adjustment, and monitoring of training programs, assisting coaches in decision making to optimize performance and mitigate injury risks for female hockey players

ISOKINETIC STRENGTH IN FEMALE SOCCER PLAYERS BY PLAYER POSITION

This study aimed to establish reference values and compare isokinetic performance in female soccer players according to player position. Eighty-seven female soccer players from the Chilean first-division soccer clubs were evaluated in isokinetic strength. The player position was grouped as goalkeeper (GK), central defender (CD), lateral defender (LD), midfielder (MF), and forward (FW). Concentric knee extension and flexion muscle strength measurements were conducted using a standardized test protocol with an angular velocity of 60º/sec. There were no differences in peak torque of knee extension and flexion between player positions in both the dominant leg (DL) and the nondominant leg (NDL). The H:Q ratio shows significant differences (p=0.0379) in the dominant leg between CD vs. MF (GK: 63.1±11.1; CD: 55.6±4.6; LD: 62.5±9.6; MF: 64.8±12.0; FW: 61.1±10.9). Our results can be used for practitioners working with female professional soccer players to assess and monitor strength according to player position to improve performance. Future studies should confirm whether these values can be used as risk factors, complementing other functional metrics (e.g., eccentric force) and different angular velocities

ELECTROMYOGRAPHIC INTER-LIMB ASYMMETRY IN BENCH PRESS EXERCISE IN ELITE PARALYMPICS WEIGHTLIFTERS

The purpose of this study was to describe inter-limb asymmetry in three muscle groups in a sample of Paralympic weightlifters during an 80% RM bench press. The sample was composed of 7 subjects belonging to the Chilean elite powerlifting. Surface electromyography was assessed in major pectoral, deltoid anterior and triceps brachii. The magnitude of the response was calculated through root mean square (RMS). Symmetry Index was calculated for an interlimb differences measure. Only the pectoralis major muscle showed significant differences between limbs (right 84.7 ± 41.3; left 66.1 ± 19.3 RMS) (p=0.05) and the SI median greatest value (19.74 ± 24.59%). Anterior deltoid showed high individual differences in two athletes with upper 80% SI values. More studies should assess asymmetry with the objective to decrease this injuries risk factor

CORRELATION BETWEEN JUMP HEIGHT AND BIOMECHANICAL VARIABLES IN CHILEAN ATHLETES OF TEAM SPORTS

I In elite team sports technical skills and explosiveness are essential to get the optimum performance, being the vertical jump one of the most important motor skills in competition, usually assessed by countermovement jump (CMJ). The main aim of our study is to determine the correlation between jump height and kinetic and kinematic variables using force platforms, and secondly to describe CMJ values of elite Chilean team sports athletes. The results obtained in our study showed a positive correlation between jump height and concentric mean power, concentric peak velocity, concentric peak power and total concentric impulse. These results are fundamental for an optimal analysis of athletes jumping tests, based on data from the specific study population and the use of those variables that are most related to their performance

Effects of weight divisions in time-motion of female high-level Brazilian Jiu-jitsu combat behaviors

Coaches and psychologists can use time-motion analysis to elaborate specific interventions for female BJJ athletes, increasing specific training context and reducing unnecessary psychological and physical demands and injuries. Therefore, the present study aimed to analyze high-level BJJ female athletes in the 2020 Pan-American Games by comparing the weight categories on the time-motion analysis. The time-motion analysis (i.e., approach, gripping, attack, defensive actions, transition, mounting, guard, side control, and submissions) of 422 high-level female BJJ combats was divided and compared by weight category as follows: Rooster (n = 8), Light Feather (n = 18), Feather (n = 122), Light (n = 84), Middle (n = 74), Medium Heavy (n = 44), Heavy (n = 36), Super Heavy (n = 36), using p ≤ 0.05. The main results indicated that the Super heavyweight category [3.1 (5.8;119.9) s] had a shorter gripping time than other weight categories, p ≤ 0.05. In contrast, roosters [7.2 (3.5;64.6) s] had longer gripping, transition [14.0 (4.8;29.6) s], and attack time [76.2 (27.7, 93.2)] than the light feather, middlers, and heavier weight categories, p ≤ 0.05. These findings should be considered for the psychological interventions and training prescription