Introduction Weight training is a useful tool in order to achieve muscular hypertrophy. However, the American College of Sports Medicine (ACSM) recommends intensities of 70% of one repetition maximum (1-RM). Those intensities may not be suitable for everyone because of the high mechanical stresses placed upon the joints [Loenneke, 2012]. Nowadays, it is common to combine low-intensity exercise (20–30% 1-RM) with blood flow restriction (BFR) because of the beneficial effects in increased muscular strength, hypertrophy, localised endurance and cardiorespiratory endurance [Pope, 2013]. Despite there is not many papers about the beneficial of this training, it is know that the tendon suffers some adaptation to physical loading [Heinemeier 2011]. Therefore, the purpose of this study was to investigate the effects of low-intensity (30% 1-RM) concentric exercise combined with BFR in the thickness of Achilles tendon.
Methods Twelve college-aged male participants aged 24 ± 4 years and three female aged 27 ± 3 (body mass 25 ± 4, height 178 ± 7 cm, weight 79,0 ± 13 kg) with a minimum of 1 year of strength training experience were recruited for this study. Prior to testing the concentric 1-RM for each leg was determined. For the exercise session, the exercise intensity was set at 30% 1-RM for each leg. The right leg of each subject was included in the occlusive group and the left leg in the control group. The subjects’ occluded legs were wrapped at a 30% of maximum pressure. Subjects performed three sets of 15 repetition of Leg-Press Calf Raise in a leg press machine. The control group (left leg) did the same protocol without BFR. The thickness of Achilles tendon was measure in each subject before the testing, immediately after exercise and 24 h after exercise by ultrasound (Mindray Z6).
Results To verify that there are no significant differences between pre and post-24 measures tendon. Wilcoxon test with a significance level of 5% was applied proving that there is no such difference.
Discussion The main finding of this research is that the occlusive training did not change the behaviour of the tendon. There is not significant differences between the control group and the occlusive group. Therefore, it is suggest that the occlusive condition does not produce any additional disturbance on tendon. In addition, this training could be useful for individuals with muscular diseases, or those who cannot lift sufficiently high loads to increase muscle size and strength.
References Heinemeier et al. J Musculoskelet Neuronal Interac. 2011;11:115–23
Loenneke et al. Med Hypotheses. 2012;78:523–7
Pope et al. J Strength Cond Res. 2013;27:2914–26
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