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- Correlations between biomechanical variables and sprint time of 30mPublication . Gil, Maria Helena Gonçalves; Marques, MC; Neiva, Henrique; Mendes, Pedro; Sousa, António; Alves, Ana Ruivo; Branquinho, Luís; Faíl, Luís Brandão; Pinto, Diogo; Marques, Diogo; Graça, Cláudia; Marinho, DanielIntroduction: Sprinting contributes to successful performance in the wide range of sporting activities. It’s known that sprinting speed is defined with the frequency and the length of strides (Čoh, Tomažin & Rausavljević, 2007). According Bezodias et al. (2008) the frequency of stride (FS) was a more important contributor to the velocity increase in sprint performance, however for Mackala (2007) the length of stride (LS) was a more significant variable. The aim of this study is to determine if different types of heating can interfere with the frequency and length variability of the stride. Methods: 22 young men participated in this study (age: 19.32±1.43 years; height: 176±67cm; weight: 68.48±9.91kg). The study followed a randomized protocol and the subjects were submitted to three warm-up protocols: without warm-up, typical warm-up and warm-up with post-activation potentiation (PAP). Results: The results reveal a strong correlations between the sprint time of 30m and the frequency of stride and length of stride. Discussion: Regardless of the type of warm-up, we can observe that the frequency and length stride are relevant factors that contribute to sprint time performance. The results corroborated with other studies indicating that maximum speed results from an optimal ratio between stride frequency and stride length. Conclusion: The frequency and length of stride were shown to be two influential factors in the sprint time of 30m. We suggest that future studies include exercises on warm-up that stimulate the frequency and amplitude of stride, in order to verify which of the variables has the greatest impact on sprint performance.
- The effect of warm-up on sprinting kinematicsPublication . Morouço, Pedro; Gil, Maria Helena; Neiva, Henrique; Marques, MC; Sousa, António; Marinho, DanielThe purpose of this study was to verify the effects of warm-up on kinematic variables during short distance repeated sprints. Twenty-two college students randomly performed 2 x 30-m running time-trials after warm-up or with no warm-up, in different days. Performance (time-trial) and biomechanical (step length and step frequency) were assessed during both repeated trials. Performance was 0.5% faster after warm-up in the first 30-m time-trial (p = 0.03, d = 0.44), but without differences on step length and frequency. The second sprint was not different between conditions, but it was better than the first sprint in the no warm-up condition. This condition also led to higher changes between the first and second sprint. Thus, the warm-up is suggested to improve maximal running performances and maintaining kinematics more similar throughout the sprints.
- Effects of Low-Moderate Load High-Velocity Resistance Training on Physical Performance of Under-20 Futsal PlayersPublication . Marques, Diogo; Travassos, Bruno; Sousa, António; Gil, Maria Helena; Ribeiro, João; Marques, MCResistance training (RT) is an effective methodology to improve physical performance of athletes. However, up to now, no studies have addressed the RT benefits in under-20 futsal players. The purpose of this study was to evaluate the effects of six weeks of RT with high-velocity movements, low-to-moderate loads, and low volume on physical performance of under-20 futsal players. A total of 21 players were divided into two groups: A control group (CG, n = 10) and a RT group (RTG, n = 11). The RTG performed two weekly training sessions constituted by leg-press, jumps, and sprints, along with three futsal training sessions, while the CG only performed the futsal training. Before and after the intervention, the sprint time in 0⁻10 m (T10), 10⁻20 m (T10⁻20), and 0⁻20 m (T20), the countermovement jump (CMJ) height, the T-Test time, the kicking ball speed (KBS), and the maximum dynamic strength in the leg-press, were assessed. In post-test, significant improvements in CMJ, T-Test, KBS, and leg-press were found for the RTG, whilst a significant decrease in T10⁻20 was evidenced in the CG. The present results suggested that RT based on high velocity movements, low-to-moderate loads, and low volume produce positive effects on physical performance of under-20 futsal players.