Higher torque and muscle fibre conduction velocity of the Biceps Brachii in karate practitioners during isokinetic contractions

Purpose: Although upper limb techniques are largely utilized during karate combat competitions scarce information regarding their NM control is available. This study aims at investigating the effect of karate practice on the NM control of Biceps and Triceps Brachii during isokinetic contractions to enhance current knowledge on neuromuscular control adaptations and training methodologies in combat sports.Methods: Torque and surface electromyograms (sEMG) of Biceps Brachii Caput Longum (BB) and Triceps Brachii Lateral Head (TB) were recorded in eight karate practitioners (KA) and eight age-matched sedentary individuals (CO) during isokinetic elbow flexion-extensions (0-240 degrees/s(-1)). BB and TB sEMG amplitude (Root Mean Square - RMS) and frequency (Median Frequency - MDF) were computed during agonist and antagonist activity. Moreover, muscle fibre conduction velocity (MFCV) of the BB was computed.Results: During the isokinetic contractions, KA group demonstrated higher peak torque and higher MFCV in the BB with respect to CO. KA and CO presented comparable activation of agonist and antagonist muscles and comparable frequency content in both BB and TB.Conclusions: The greater torque observed in KA should be interpreted in the light of a different motor unit recruitment strategy as suggested by the higher MFCV. Karate and combat sport practitioners should consider including in their training programmes methodologies emphassing neural rather than morphological adaptations.