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Browsing Artigos em revistas indexadas by Subject "Adolescent"
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- Behavioural variability and motor performance: Effect of practice specialization in front crawl swimmingPublication . Seifert, L.; De Jesus, K.; Komar, J.; Ribeiro, J.; Abraldes, J.A.; Figueiredo, P.; Vilas-Boas, J.P.; Fernandes, R.J.The aim was to examine behavioural variability within and between individuals, especially in a swimming task, to explore how swimmers with various specialty (competitive short distance swimming vs. triathlon) adapt to repetitive events of sub-maximal intensity, controlled in speed but of various distances. Five swimmers and five triathletes randomly performed three variants (with steps of 200, 300 and 400m distances) of a front crawl incremental step test until exhaustion. Multi-camera system was used to collect and analyse eight kinematical and swimming efficiency parameters. Analysis of variance showed significant differences between swimmers and triathletes, with significant individual effect. Cluster analysis put these parameters together to investigate whether each individual used the same pattern(s) and one or several patterns to achieve the task goal. Results exhibited ten patterns for the whole population, with only two behavioural patterns shared between swimmers and triathletes. Swimmers tended to use higher hand velocity and index of coordination than triathletes. Mono-stability occurred in swimmers whatever the task constraint showing high stability, while triathletes revealed bi-stability because they switched to another pattern at mid-distance of the task. Finally, our analysis helped to explain and understand effect of specialty and more broadly individual adaptation to task constraint.
- Biomechanical analyses of synchronised swimming standard and contra-standard scullingPublication . Gomes, Lara Elena; Diogo, Vera; Castro, Flávio Antônio de Souza; Vilas-Boas, João Paulo; Fernandes, Ricardo J.; Figueiredo, PedroSynchronised swimming involves a variety of sculling movements essential for body support and propulsion but its study is scarce. We aimed to biomechanically compare standard and contra-standard sculling techniques, and to observe the relationship between measures. Six synchronised swimmers performed two, 30 s maximal intensity, fully tethered standard and contra-standard sculling motions. Kinetic and kinematic data were obtained using a load-cell and underwater cameras, respectively. Force decreased along both techniques' bouts, but no differences in-between techniques were noted for any kinetic variables. Standard sculling presented a higher cycle rate and a lower elbow mean angle than the contra-standard sculling (2.4 ± 0.3 vs. 2.0 ± 0.2 cycles/s and 134.1 ± 5.8 and 141.5 ± 4.7°, p < 0.05). In the standard sculling, by removing and maintaining the variation between participants (r w and r, respectively), the absolute mean force was directly related with cycle rate (r w = 0.60) and wrist angular velocity during flexion (r = 0.82), while in the contra-standard condition the force was inversely associated with wrist mean angle (r = -0.95) and directly with hand speed (r w = 0.76), and elbow angular velocity (r w ≈ 0.60). Therefore, technique learning and training require different attention by coaches and swimmers.
- Does Warm-Up Have a Beneficial Effect on 100-m Freestyle?Publication . Neiva, Henrique P.; Marques, Mario C.; Fernandes, Ricardo J.; Viana, João L.; Barbosa, Tiago M.; Marinho, Daniel A.To investigate the effect of warm-up on 100-m swimming performance.
- Effects of 10min vs. 20min passive rest after warm-up on 100m freestyle time-trial performance: A randomized crossover studyPublication . Neiva, Henrique P.; Marques, Mário C.; Barbosa, Tiago M.; Izquierdo, Mikel; Viana, João L.; Marinho, Daniel A.The aim of this study was to compare the effect of 10min vs. 20min passive rest post warm-up on performance in a 100m freestyle time-trial.
- Effects of different re-warm up activities in football players' performancePublication . Abade, Eduardo; Sampaio, Jaime; Gonçalves, Bruno; Baptista, Jorge; Alves, Alberto; Viana, JoãoWarm up routines are commonly used to optimize football performance and prevent injuries. Yet, official pre-match protocols may require players to passively rest for approximately 10 to 15 minutes between the warm up and the beginning of the match. Therefore, the aim of this study was to explore the effect of different re-warm up activities on the physical performance of football players. Twenty-Two Portuguese elite under-19 football players participated in the study conducted during the competitive season. Different re-warm up protocols were performed 6 minutes after the same standardized warm up in 4 consecutive days in a crossover controlled approach: without, eccentric, plyometric and repeated changes of direction. Vertical jump and Sprint performances were tested immediately after warm up and 12 minutes after warm up. Results showed that repeated changes of direction and plyometrics presented beneficial effects to jump and sprint. Different practical implications may be taken from the eccentric protocol since a vertical jump impairment was observed, suggesting a possibly harmful effect. The absence of re-warm up activities may be detrimental to players' physical performance. However, the inclusion of re-warm up prior to match is a complex issue, since the manipulation of volume, intensity and recovery may positively or negatively affect the subsequent performance. In fact, this exploratory study shows that eccentric exercise may be harmful for physical performance when performed prior a football match. However, plyometric and repeated changes of direction exercises seem to be simple, quick and efficient activities to attenuate losses in vertical jump and sprint capacity after warm up. Coaches should aim to develop individual optimal exercise modes in order to optimize physical performance after re warm activities.
- Exploring the Effects of Playing Formations on Tactical Behavior and External Workload During Football Small-Sided GamesPublication . Baptista, Jorge; Travassos, Bruno; Gonçalves, Bruno; Mourão, Paulo; Viana, João L.; Sampaio, JaimeBaptista, J, Travassos, B, Gonçalves, B, Mourão, P, Viana, JL, and Sampaio, J. Exploring the effects of playing formations on tactical behavior and external workload during football small-sided games. J Strength Cond Res 34(7): 2024-2030, 2020-This study aimed to identify the effects of playing formations on tactical behavior and external workload during football small-sided games. Twenty-three semiprofessional footballers integrated 3 different playing formations in a 7-a-side small-sided game, according to their specific player positions: team 4:3:0 (4 defenders and 3 midfielders); team 4:1:2 (4 defenders, 1 midfielder, and 2 forwards); and team 0:4:3 (4 midfielders and 3 forwards). Based on players' movement trajectories, the following individual and collective tactical variables were calculated: total distance covered and distance covered while walking, jogging, running, and sprinting, distance from each player to both own-team centroid and opponent-team centroid, individual area, team length, team width, and surface area. Approximate entropy was computed to identify the regularity of each variable. The team 4:3:0 promoted players' space exploration with moderate physical efforts. The team 4:1:2 promoted compactness and regularity of the team with increase in the physical efforts. The team 0:4:3 promoted team balance and adaptability on space coverage with increase in physical efforts. Concluding, different playing formations support different game dynamics, and variations on external load were directly linked with the variations on tactical behavior. The analysis of tactical behavior through quantification of variability of patterns of play and quantification of distance covered at different velocities were the most useful information for the analysis of the effects of practice task manipulations. Therefore, in a practical sense, strength and conditioning coaches should plan and monitor these tasks in interaction with the head coaches.
- Factors Related to Sports Participation in Brazil: An Analysis Based on the 2015 National Household SurveyPublication . Magno, Felipe; ten Caten, Carla Schwengber; Reppold Filho, Alberto Reinaldo; Callegaro, Aline Marian; Ferreira, Alan de Carvalho DiasThe academic interest in analyzing the correlates of sports participation in several countries has increased recently. Nevertheless, in developing countries, which do not monitor sportive data, this type of investigation is still scarce. This study aims to analyze socioeconomic, motivational, and supportive factors related to sports participation in Brazil. Data from the 2015 National Household Survey-Supplementary Questionnaire of Sports and Physical Activities are examined. In the survey, 71,142 individuals older than 15 years were interviewed (mean age 43.12 years; 53.83% women and 46.17% men). Logistic regression is used for analyzing the data. Results demonstrate a low participation in sports (23.38%). Sports participation declines with increasing age (2% less per year), increases with higher educational level (graduated 5.9 times more), and males prevail in the sporting context (2.3 times more). The main obstacle to women's participation is the lack of sports facilities, and for men the lack of time and health problems. Men practice sports mainly due to socialization, fun, and competition, and women due to medical recommendation. Soccer was the most practiced sport (28.1%), predominating among men. Public policies on sports promotion for fun and socialization may increase male participation, and investments in sports facilities may increase female participation.
- High-intensity Interval Training in Different Exercise Modes: Lessons from Time to ExhaustionPublication . Sousa, Ana; Fernandes, Ricardo; Boas, Joao; Figueiredo, PedroTo provide information for high-intensity interval training (HIIT) load, we compared the temporal variables of VO2 response at, and after, a time sustained at the exercise intensity corresponding to VO2max (Tlim) in different exercise modes. Forty-five trained male swimmers (11), rowers (13), runners (10) and cyclists (11) completed an incremental protocol to determine the velocity (vVO2max) or power (wVO2max) at VO2max and a square wave exercise from rest to 100% of vVO2max/wVO2max. The temporal variables of VO2 response were examined using a breath-by-breath gas analyzer. VO2 responses were not different between exercise modes, except for the percentage of VO2max at 50% of Tlim, which was ~6% higher in rowing compared to cycling (97.70±2.90 vs 92.40±5.69%, p=0.013). During the recovery period, both swimmers and rowers evidenced higher percentages of VO2max compared to cyclists at 30 s (65.1±10.4 and 65.7±5.6 vs 52.7±5.6%) and 60 s (41.7±10.8 and 38.4±5.4 vs 30.4±1.8%) time periods, all for p<0.01. Furthermore, swimmers presented higher time values to reach 50% VO2max compared to runners and cyclists (51.1±15.6 vs 38.1±6.7 and 33.8±4.7%; p<0.001). When training at 100% of VO2max intensity, fixed intervals for HIIT could be set freely. However, recovery periods based on time or intensity are exercise-mode dependent.
- Integrated Analysis of Young Swimmers’ Sprint PerformancePublication . Silva, Ana F.; Figueiredo, Pedro; Ribeiro, João; Alves, Francisco; Vilas-Boas, João Paulo; Seifert, Ludovic; Fernandes, Ricardo J.To analyze young swimmers' performance regarding sex and skill level, 23 boys and 26 girls (15.7 ± 0.8 and 14.5 ± 0.8 years old, respectively) were assessed for anthropometry, flexibility, strength, drag, coordination, and biomechanical variables. During a 50-m maximal front-crawl bout, seven aerial and six underwater Qualisys cameras assessed kinematics, and a load cell was used to measure drag (Tedea, United Kingdom) and tethered swimming force. A multivariate analysis of variance test (p < .05) enabled us to observe differences between skill levels in speed, stroke frequency, stroke index, and intracyclic velocity variations, but most relevant differences were noticed when comparing sexes, particularly for anthropometrics, shoulder flexibility, speed, stroke frequency, stroke length, drag, mechanical power, power per stroke, and maximal and mean force. Considering the included variables, only male swimmers' performance could be predicted through multiple linear regression, with stroke index, left shoulder flexion, and intracycle velocity variations showing great importance in achieving better results.
- Key determinants of time to 5 m in different ventral swimming start techniquesPublication . Peterson Silveira, Ricardo; Stergiou, Pro; Figueiredo, Pedro; Castro, Flávio de S.; Katz, Larry; Stefanyshyn, Darren J.The aim of this study was to determine the biomechanical parameters that explain ventral start performance in swimming. For this purpose, 13 elite swimmers performed different variants of the ventral start technique. Two-dimensional video analyses of the aerial and underwater phases were used to assess 16 kinematic parameters from the starting signal to 5 m, and an instrumented starting block was used to assess kinetic data. A Lasso regression was used to reduce the number of parameters, providing the main determinants to starting performance, revealing different combinations of key determinants, depending on the variant (r² ≥ 0.90), with flight distance being the most relevant to all variants (r ≤ -0.80; p < .001). Also, special attention should be given to the total horizontal impulse in the grab start (r = -0.79; p < .001) and to the back foot action in the track and kick starts (r ≤ 0.61; p < .001). In addition, we provide two equations that could be easily used to predict starting performance by assessing block time and flight time (r² = 0.66) or block time and flight distance (r² = 0.83). These data provide relevant contributions to the further understanding of the biomechanics of swimming starts as well as insights for performance analysis and targeted interventions to improve athlete performance.