THE EFFECTS OF ISOMETRIC EXERCISE ON VASTUS MEDIALIS AND RECTUS FEMORIS MUSCLES USING EMG ANALYSIS.

1431 This study aimed to reveal the effects of isometric strength training on isometric strength and integrated EMG (IEMG) activities of vastus medialis(VM) and rectus femoris (RF) muscles at various knee angles (30-60-90-120°) and tibial positions (internal-external rotations and neutral). Ten healthy male subjects (Age: 20.4 ± 1.5) were trained at 90 ° knee angle and neutral position for 8 weeks. Maximal isometric contractions were performed by each subject using a fitness machine. Isometric training regime consisted of 3 sets/day for 3 days/week. Each set consisted of 6, 9, and 12 second contractions with 90-120 second rest intervals. IEMG activities were measured at wall stance position using surface electrodes. Post-training IEMG activities were significantly lower than pre-training values at every angle and position studied (p<0.05). Training was associated with increase in isometric strength at all knee angles (p<0.05). Compared to 30 and 60 degrees, this increase was higher in 90 and 120 degree knee flexion(p<0.05). IEMG activities in VM were higher than in of RF at 90 and 120 degrees knee flexion in each tibial position. It can be concluded that 90 degree knee flexion at a neutral tibial position may be used to perform isometric quadriceps exercise to improve or maintain isometric strength.