Eletromyographic study of the Rectus femoris and Bíceps femoris (long head) muscles during bilateral isotonic contraction in a 450 leg press apparatus

Abstract

The aim of this study was to compare the bilateral electric activity of the rectus femoris (RF) and biceps femoris long head (BF) muscles during flexion and extension isotonic movements of the thigh and leg. Six men and six women accomplished all movements in 45° Leg Press apparatus with 30% and 60% of the maximum voluntary load (MVL). Electromyographic signs were captured using surface electrodes, recorded in a computerized electromyograph and analyzed in a system of data acquisition (Alc-EMG). The results demonstrated that the RF muscle showed greater electric activity than BF in both loads (30% and 60% MVL) and sides, regardless the sex. It can be concluded that in spite of the RF and BF muscles are in opposite ends of the hip and knee joints and are mentioned traditionally as antagonistic muscles, both muscles seem to act with synergism between themselves with predominance of the activation of the RF muscle on the BF muscle in both genders and studied loads in leg press 45o execution. In addition, the electrical activity of these muscles is directly proportional to the load, ndependently of the sex.

Keywords

• Kinesiologic EMG
• Leg Press
• Rectus femoris
• Biceps femoris.