A navegação consulta e descarregamento dos títulos inseridos nas Bibliotecas Digitais UC Digitalis, UC Pombalina e UC Impactum, pressupõem a aceitação plena e sem reservas dos Termos e Condições de Uso destas Bibliotecas Digitais, disponíveis em https://digitalis.uc.pt/pt-pt/termos. Conforme exposto nos referidos Termos e Condições de Uso, o descarregamento de títulos de acesso restrito requer uma licença válida de autorização devendo o utilizador aceder ao(s) documento(s) a partir de um endereço de IP da instituição detentora da supramencionada licença. Ao utilizador é apenas permitido o descarregamento para uso pessoal, pelo que o emprego do(s) título(s) descarregado(s) para outro fim, designadamente comercial, carece de autorização do respetivo autor ou editor da obra. Na medida em que todas as obras da UC Digitalis se encontram protegidas pelo Código do Direito de Autor e Direitos Conexos e demais legislação aplicável, toda a cópia, parcial ou total, deste documento, nos casos em que é legalmente admitida, deverá conter ou fazer-se acompanhar por este aviso.

The study aimed to identify how the manipulation of knowledge regarding a training task duration constrains the pacing and tactical behaviour of soccer players when playing small-sided games (SSG). Twenty professional and experienced soccer players participated in a cross-sectional field study using three conditions: not informed on the duration of the SSG, which ended after 20 min (Unknown Condition); briefed about playing the SSG for 10 min, but after they completed the 10-min game, they were requested to complete another 10 min (Partial Condition) and informed before that they would play for 20 min (Known Condition). A global positioning system was used to measure the total distance covered and distances of different exercise training zones (walking to sprinting) and to access the dynamic players positioning through the distance from each player to all the teammates and opponents. Additionally, approximate entropy was measured to identify the regularity pattern of each gathered individual variable. The results indicate that the first 10 min of each scenario presented a higher physical impact independently of the initial information. During this time, the tactical behaviour also revealed higher variability. An increase in the distance of the teammates during the second period of 10-min for the Known scenario was also found, which may result from a lower pacing strategy. This study showed that the prior knowledge of the task duration led to different physical and tactical behaviours of the players. Furthermore, the relationship between the physical impact and the regularity of team game patterns should be well analysed by the coach, because the physical impact may be harmful to the development of the collective organization of the team.

Purpose: To verify the effects of using different grip widths in bench press performance in Paralympic powerlifting athletes. Methods: Twelve experienced Paralympic powerlifting male athletes (25.40 [3.30] y, 70.30 [12.15] kg) participated in the study. Maximal dynamic strength and maximal isometric strength (MIS) were determined. Then, mean propulsive velocity (MPV) using 25%, 50%, and 100% of maximal dynamic strength load and time to achieve 30%, 50%, and 100% of MIS were assessed with 4 different grip widths, specifically the biacromial distance (BAD: 42.83 [12.84] cm), 1.3 BAD (55.68 [16.70] cm), 1.5 BAD (63.20 [18.96] cm), and 81 cm. Electromyographic analysis was performed during MIS assessment in the pectoralis major sternal portion, anterior deltoid, triceps brachii long head, and pectoralis major clavicular portion. Results: Large differences were found between MPV performed with different grip widths using 25% of maximal dynamic strength load (P = .02, ). The 1.5 BAD grip tended to show greater force generation and MPV. Moreover, the time needed to achieve 30%, 50%, and 100% of MIS differed between grip widths (P = .03, ), with the lowest values obtained in the 1.5 BAD. Despite the nonstatistical differences that were found, grip widths caused moderate effects on muscle myoelectric activation, showing greater values for pectoralis major clavicular portion and pectoralis major sternal portion, for the 1.3 BAD and 1.5 BAD, respectively. The 1.5 BAD the grip width tended to show greater MPV values and faster contractile responses. Conclusions: These results highlighted the importance of choosing the specific grip width for improvement of performance in Paralympic powerlifting athletes, by increasing velocity of movement and force production in a shorter time, with greater activation of primary muscles.

Abstract:The proprieties of a skeletal muscle were examined using the method Tensiomyography (TMG) in team sports high-level athletes who contracted a skeletal muscle injury, lesion confirmed by a magnetic resonance image (MRI). The analysis by the TMG is performed during the rehabilitation process, a non-invasive method, allowing the recording of chances in muscle following parameters: Td (time of reaction); Tc (time of contraction); Dm (maximum displacement); Tr (time of relaxation) and Ts (time of during contraction). Therefore, the aim of the study is to analyze the muscular reaction to the process of rehabilitation training.

Purpose:The purpose of this study was to determine whether two throwing programs, based upon velocity or resistance with the same workload, would enhance soccer overhead throwing velocity.Methods:Sports science students (n = 64, age 21.1 ± 2.1 y, mass 71.1 ± 11 kg, height 1.75 ± 0.09 m; mean ± SD) divided into two groups matched on performance, participated in the study. The resistance-training group trained overhead throwing with a 5-kg medicine ball for two sets of 8 reps per session, whereas a velocity training group threw four sets of 16 reps with a regular soccer ball. These training programs were matched on workload. Throwing performance with a soccer ball and a 5-kg medicine ball were tested before and after a training period of 6 wk with two sessions per week.Results:Both groups significantly increased the throwing velocity with the soccer ball (resistance-training group: 3.2% [1.0–5.5%)]; P = .003 and velocity-training group: 5.1% [2.6–7.7%]; P < .001), whereas no substantial changes were found for throwing with the 5-kg medicine ball after the training period. No substantial differences between the groups were found, which indicates that both forms of training increased the throwing velocity.Conclusions:It is concluded that both velocity and resistance throwing training programs after a short period of training with the same workload can increase throwing velocity and that workload is of importance in designing training programs and comparing them with each other.

The current study aims to verify the effects of three specific warm-ups on squat and bench press resistance training. Forty resistance-trained males (19–30 years) performed 3 × 6 repetitions with 80% of maximal dynamic strength (designated as training load) after one of the following warm-ups (48 h between): (i) 2 × 6 repetitions with 40% and 80% of the training load (WU), (ii) 6 × 80% of training load (WU80), or (iii) 6 × 40% of the training load (WU40). Mean propulsive velocity (MPV), velocity loss (VL), peak velocity (PV), time to achieve PV, power, work, heart rates, and ratings of perceived exertion were analyzed. In squat exercises, higher MPV were found in WU80 compared with WU40 (2nd set: 0.69 ± 0.09 vs. 0.67 ± 0.06 m.s−1, p = 0.02, ES = 0.80; 3rd set: 0.68 ± 0.09 vs. 0.66 ± 0.07 m.s−1, p = 0.05, ES = 0.51). In bench press exercises, time to PV was lower in WU compared with WU40 (1st set: 574.77 ± 233.46 vs. 694.50 ± 211.71 m.s−1, p < 0.01, ES = 0.69; 2nd set: 533.19 ± 272.22 vs. 662.31 ± 257.51 m.s−1, p = 0.04, ES = 0.43) and total work was higher (4749.90 ± 1312.99 vs. 4631.80 ± 1355.01 j, p = 0.01, ES = 0.54). The results showed that force outputs were mainly optimized by WU80 in squat training and by WU in bench press training. Moreover, warming-up with few repetitions and low loads is not enough to optimize squat and bench press performances.

Backpacks for transporting school loads are heavily utilized by children, and their mechanical advantages have been allowing children to transport heavy loads. These heavy loads may increase ground reaction forces (GRFs), which can have a negative effect on joints and bone health. The aim of this study was to investigate the effect of backpacks on the GRFs generated by children during walking, running, and jumping. Twenty-one children from the fifth (G-5, n = 9) and ninth (G-9, n = 12) grades walked, ran, and jumped over a force plate. When walking, the G-5 had GRF increments in the first (17.3%; p < 0.001) and second (15.4%; p < 0.001) peak magnitude, and in the total integral of the vertical force (20%; p < 0.001), compared to the control condition (i.e., no backpack), and the G-9 had increments of 10.4%, 9%, and 9% (p < 0.001), respectively. The G-9 did not prolong their total stance time (p > 0.05), unlike the G-5 (p = 0.001). When running, total stance time increased 15% (p < 0.001) and 8.5% (p < 0.001) proportionally to the relative load carried, in the G-5 and G-9, respectively. Peak GRF did not increase in any group when running or landing from a jump over an obstacle. It was found that GRF was affected by the backpack load when walking and running. However, when landing from a jump with the backpack, schoolchildren smoothed the landing by prolonging the reception time and thus avoiding GRF peak magnitudes.

No abstract