Acute effects of different intervals between repeated sprints on performance responses in amateur futsal athletes / Efeitos agudos de diferentes intervalos entre sprint repetidos sobre as respostas de desempenho em atletas amadores de futsal

ABSTRACT Objective: Verify the influence of different break times between sprints on the performance of amateur futsal athletes. Methods: 10 individuals, men, amateur futsal athletes (Age: 21.5 ± 1.6; Weight: 72.4 ± 6.88; Height: 1.72 ± 0.05; BMI: 24.3 ± 1.2; Fat%: 13.7 ± 3.3, VO2peak: 49.1 ± 10.5) participated in the study. Individuals were randomly selected to perform sessions with sprints (10 sets 20 m) with different pause times of 15 (S15), 30 (S30) and 60 (S60) seconds. For performance analysis, the speed (km / h) applied to each sprint was used and monitored by a device with a photocell (CEFISE Biotecnologia Esportiva®). Results: There was an interaction between speed and interval time (p = 0.000). For condition S15, a greater reduction in performance was observed (p ≤ 0.05), while for S30 and S60, no significant reduction in performance was observed (p > 0.05). The data for the area under the curve showed a significant difference (p = 0.000), where the interval of 60 s (S60) was longer compared to the values of 30 (S30) (p = 0.000) and 15 s (S15) (p = 0.000). However, there were no significant differences between the 30 and 15 s data (p = 0.248). Conclusion: A shorter time (15 s) interval between repeated sprints can significantly affect performance compared to longer breaks (30 and 60 s), but all the conditions tested here can be positive for the improvement of performance, mainly in sports that demand fast and efficient motor actions such as futsal.

RESUMO Objetivo: Verificar a influência dos diferentes tempos de intervalo entre os sprints no desempenho dos atletas de futsal amadores. Métodos: 10 indivíduos, homens, atletas de futsal amadores (Idade: 21,5 ± 1,6; Peso: 72,4 ± 6,88; Altura: 1,72 ± 0,05; IMC: 24,3 ± 1,2; Gordura%: 13,7 ± 3,3, VO2peak: 49,1 ± 10,5) participou no estudo. Os indivíduos foram selecionados aleatoriamente para realizar sessões com sprints (10 conjuntos 20 m) com diferentes tempos de pausa de 15 (S15), 30 (S30) e 60 (S60) segundos. Para análise do desempenho, a velocidade (km/h) aplicada a cada sprint foi utilizada e monitorizada por um dispositivo com uma fotocélula (CEFISE Biotecnologia Esportiva®). Resultados: Houve uma interação entre velocidade e tempo de intervalo (p = 0,000). Para a condição S15, observou-se uma maior redução no desempenho (p ≤ 0,05), enquanto para S30 e S60, não se observou qualquer redução significativa no desempenho (p > 0,05). Os dados para a área sob a curva mostraram uma diferença significativa (p = 0,000), onde o intervalo de 60 s (S60) foi mais longo em comparação com os valores de 30 (S30) (p = 0,000) e 15 s (S15) (p = 0,000). No entanto, não houve diferenças significativas entre os dados de 30 e 15 s (p = 0,248). Conclusão: Um intervalo de tempo mais curto (15 s) entre sprints repetidos pode afetar significativamente o desempenho em comparação com os intervalos mais longos (30 e 60 s), mas todas as condições aqui testadas podem ser positivas para a melhoria do desempenho, principalmente nos desportos que exigem ações motoras rápidas e eficientes, tais como o futsal.

The Effect of Repeated-sprint Training on The Speed-endurance of Basketball Players in Hypoxia Environment / 中国运动医学杂志

Objective To observe the effect of a repeated-sprint training on the speed-endurance of basketball players in a hypoxia environment.Methods Sixteen basketball players were divided into a hypoxiagroup and a normoxia group which had 8 persons each group.The 2 groups separatelyhad a repeated-sprint training with anaerobic power bicycles in a simulatedhypoxic environment at the altitude of 3000 meters and a normoxia environment for 4 weeks(twice a week).Before and after the training,the two groups of subjects had a shuttle run testing and a Wingateanaerobic powertestingin a normoxia environment.Then their blood were collected and measured the blood lactate level at the point-intime of after the shuttle run,3 min later,5 min later,7 min later,and 9 min later.Recorded the result of the shuttle run,the relative average power of the Wingateanaerobic powertesting,and carried on a statistic analysis of the data.Results Comparing with the performance of the shuttle run before the training,the performance of the 2 groups was improved obviously after the four-week-long training (P＜0.05).But there was no significant difference between the 2 groups(P＞0.05).The rate of blood lacticacid clearance in the hypoxia group was higher than that in the normoxia group,and there was a significant difference at 7 min (P＜0.01).The relative average power of the hypoxia group had a significant improvement(P＜0.05),while the normoxia group had no significant change(P＞0.05).There was no significant difference of the relative average power between the two groups.Conclusion Repeatedsprint training can improve basketball players' speed-endurance.Repeated-sprint training in a hypoxic environment can effectively improve basketball players' ability of reducing blood lactate in their body,and the improvement of this aerobic ability can help athletes to have a better performance in competitions.

The Effect of Sprint and Heavy Resistance Training on Muscle Strength, Endurance and Muscle Fiber Type

OBJECTIVE: The purpose of this study is to compare muscle strength, endurance and the change of myosin heavy chain isoform after sprint training(ST) and heavy resistance training(HRT). METHOD: Fourteen young athletes were enrolled and were randomly assigned into each training group. Before and after training for 8 weeks, the strength and the endurance were evaluated using isokinetic exercise system(Cybex 6000). The specimens of muscle biopsy were obtained from vastus lateralis muscle and were analysed for muscle fiber type using one dimensional electrophoresis. RESULTS: Peak torque, total work and mean power were increased significantly in both groups, but endurance ratio increased only in the sprint training group(P0.05). CONCLUSION: This study shows that it is possible to increase muscle strength and to achieve fiber type transformation with the sprint training and the high resistance training.

Effects of intermittent-sprint training on histochemical properties of muscle fibres and dominant motor neurons in rats / 体力科学

The present study was undertaken in order to investigate effects of short-term, high intensity training on the total number and histochemical properties of fast tibialis anterior, slow soleus muscle fibres and their dominant motor neurons in male rats.<BR>The animals were subjected to 4 meters of sprint-running by the operant conditioning, 12 times a day interposed with 5 minutes rest periods for 14 weeks.<BR>This training had no effect on the total number and enzyme activities of muscle fibres and dominant neurons. However, hypertrophy of FOG and FG fibres in tibialis anterior muscle was caused by the training.<BR>The conclusion, therefore, is that short-term but high intensity training causes selec. tive hypertrophy of fast twitch muscle fibres, but does not have an influence on the histochemical properties of motor units because the training is far a short period of time.

STUDY ON OPTIMAL STARTING PERIOD OF POWER SPRINT TRAINING DURING GROWTH IN RATS / 体力科学

The purpose of this study was to investigate the optimal starting period of muscle power training during growth. Thirty-three Wistar strain male rats were used and classified into four groups, control group, 3T group started a training at 3 weeks after birth (weaning period), 8T group started a training at 8 weeks after birth (puberty period) and 13T group started a training at 13 weeks after birth (beginning of mature period) . Each training group was subjected to a power sprint training till 23 weeks after birth (mature period) .<BR>The results were summarlized as follows;<BR>1) Hypertrophy and increase of contractile properties in muscle were not seen in each training group.<BR>2) Muscle glycogen contents increased significantly in 3T group (p<0.05) and in 8T, 13T group (p<0.01) .<BR>3) Muscle fiber area increased significantly in 8T group only.<BR>4) Phosphofructokinase activity in muscle increased significantly in 8T group only.<BR>These results suggest that 8 weeks after birth, the puberty period may be the most effective starting period of power sprint training during growth in rats.