کمال رنجبر

Purpose: High-intensity interval training (HIIT) is an effective training method for improving the aerobic and anaerobic power of athletes; however, the role of activity volume in high-intensity interval training efficiency is still unclear. Therefore, in the present study, the effects of low- and high-volume HIIT on aerobic power, anaerobic power, and lactate response in young soccer players were compared. Method: In this study, 24 professional soccer players aged 20 to 22 who had no history of illness or taking supplements were chosen and randomly assigned to two groups of high-volume and low-volume HIIT. High-intensity interval training was completed for eight weeks. Training sessions included 5 min of warm-up, the main training phase, and cooling down. The training phase in the first week included 8 repetitions of 15 s of running with maximum power and 15 s of rest. Every week, the number of repetitions was increased by two. High-volume interval training was conducted for six sessions per week while low-volume interval training was performed for three sessions per week. After the training intervention, aerobic power was measured using the one-mile running test, and anaerobic power was evaluated using the Running-Based Anaerobic Sprint Test (RAST). Moreover, the level of blood lactate resulting from the RAST test was also measured using a lactometer. To statistical analyses repeated measure ANOVA was used. Results: Blood lactate levels were reduced by 12% (p=0.001) in the high-volume interval group and by 10% (p=0.001) in the low-volume interval group in response to exercise. In addition, statistical analysis revealed that the blood lactate levels in response to exercise after 8 weeks of training were similar in both groups. On the other hand, despite the rise in aerobic and anaerobic power in both groups, there was no significant difference in aerobic and anaerobic power between the high-volume and low-volume groups after eight weeks of interval training. Conclusions: Overall, the findings of the present research indicated that high-intensity interval training will reduce lactate and increase aerobic and anaerobic capacity, regardless of the training volume.

Background and purpose: Caffeine is a widely used and available physiological stimulant that is effective in sports performance. The purpose of this study was to investigate the effect of caffeine consumption and exercise on fatigue and cardiovascular responses in active men.Materials and methods: The statistical population of this research was made up of all male students of physical education in the age range of 19 to 27 years with at least three activity sessions per week. 15 of them were selected as subjects and they performed the exercise protocol in two stages (the first stage by eating placebo and the second stage by eating coffee). Subjects consumed 5 mg/kg of coffee in the first session under placebo conditions, and in the second session, subjects consumed 5 mg/kg of coffee one hour before the test. Blood samples were collected before taking placebo or caffeine and after the test. Findings: The results of the correlated t-test showed that the consumption of caffeine supplements significantly increased the time to reach fatigue and the index of oxygen consumption after exercise. In general, it can be said that active men can use 6 mg/kg of caffeine supplement one hour before sports activity to improve the time to reach fatigue.