Acute Effect of Blood Flow Restriction on Electrical Activity of Arm Muscles during Exhausting Karate Zoki in Young Men
Oral Presentation XML
1Master in Sports Biomechanics/ Faculty of Physical Education and Sport Sciences, Islamic Azad University, Central Tehran Branch
2Assistant Professor, Faculty of Physical Education and Sport Sciences, Kharazmi University
3Assistant Professor/ Faculty of Physical Education and Sport Sciences, Islamic Azad University, Central Tehran Branch, Tehran, Iran
Introduction: Athletes employ resistance training to enhance sport specific muscular development and subsequent performance. Traditional guidelines state that for substantial increases in muscle size and strength, resistance training should be performed using at least 70% of 1RM. However, increasing evidence supports the use of low-load resistance exercise combined with moderate Blood Flow Restriction (BFR) to facilitate hypertrophic and strength gains (2, 3). The purpose of this research was to investigate acute effect of BFR on electrical activity of arm muscles in karate Zoki in young men.
Methodology: Twenty young male karatekas voluntarily participated in this research (Age: 20.1± 3.47 Yr, weight: 60.62±5.32 Kg, Height: 164.69±37.74 Cm). Electrodes were placed on Biceps and lateral head of Triceps of both hands based on SENIAM protocol. Myomotion accelerometer sensors also were placed on both hands, wrists, and arms to define extension and flexion phases during Zoki throw fist. Preferred and Non-preferred arm were considered as intervention and control respectively, and researcher made cuff with 140% of participants systolic pressure was placed on the highest part of intervention arm. Participants started to Zoki throw fist with sub-maximal effort and continued throwing fist until exhaustion. Electrical activity of muscles during Zoki throw fist was captured at frequency of 1500 Hz with Myomuscle system (Noraxon, USA). Electromyographic data were high pass and low pass filtered by 18 Hz and 500 Hz cut off frequency respectively. Biceps and Triceps Integrated Electromyography (IEMG) and their coactivation were calculated for both arms.
Results: The results of independent sample t-test showed significant increase of biceps and triceps IEMG and significant decrease of coactivation at intervention arm than control (P ≤ 0.05).
Discussion: Regarding results, it can be concluded that BFR increases arm muscles activation during fatiguing Zoki throw fist at low loads, which indirectly it is a sign for activation of type II motor units. However, BFR decreased agonist and antagonist coactivation, that consequently can increase the risk for injury during elbow extension in throw fist. This decrease in coactivation could be attributed to muscle spindle activation disorder and decrease of its irritability. The results suggest that although BFR has positive effects on muscle activation during low loads, however, it may reduce coactivation of agonist and antagonist muscles that is dangerous in dynamic movements and hence, the use of this training in dynamic movements should be addressed from biomechanical perspectives.