Electromyographic analysis of exercises proposed for differential activation of medial and lateral quadriceps femoris muscle components (original) (raw)

Physical Therapy

The purpose of this study was to determine whether active exercises combining hip adduction with knee extension activate medial components of the quadriceps femoris muscle (QF) more than does knee extension alone. Twelve healthy adults (6 men, 6 women), aged 20 to 36 years (mean = 24.8, SD = 5.8), participated in the study. The subjects performed quadriceps femoris setting (QS), straight leg raising (SLR), straight leg raising with the hip laterally rotated (SLR/LR), and straight leg raising combined with isometric hip adduction (SLR/ADD). Electromyographic (EMG) activity was recorded from the oblique (VMO) and longitudinal (VML) portions of the vastus medialis, vastus lateralis (VL), and rectus femoris muscles. Comparison of normalized mean EMG magnitudes revealed that the single-joint QF components (VMO, VML, and VL) demonstrated significantly greater activity during QS than during any of the three SLR variations and that SLR/LR and SLR/ADD did not elicit greater relative activity...

Quadriceps Electromyographic Activity in Closed and Open Kinetic-Chain Exercises with Hip-Adductor Co-Contraction in Sedentary Women

International Journal of Environmental Research and Public Health

Background: Different closed and open kinetic-chain exercises with hip-adductor co-contraction have different effects on quadriceps activity. The aim of this study was to investigate the difference in quadriceps activity during the squat (SQ) and knee extension (KE) and straight leg raise (SLR) exercises with and without hip adduction in sedentary women. Methods: Twenty-eight sedentary women aged 44.5 ± 8.5 years were recruited. They performed three exercises with and without hip adduction. Surface electromyography (sEMG) activity was measured on the rectus femoris (RF), vastus medialis oblique (VMO) and vastus lateralis (VL) muscles. The levels of sEMG activities of the three muscles were compared among the six exercises using a repeated-measures ANOVA. Results: The findings showed that RF activity was lowest during the SQ alone and highest during the SLR exercise (p < 0.05 to 0.001). The VMO activity was significantly greater in the SQH than in the five types of exercises (p &l...

Effects of Knee Extension Joint Angle on Quadriceps Femoris Muscle Activation and Exerted Torque in Maximal Voluntary Isometric Contraction

Biology

This study investigated the effects of knee joint angle on muscle activation, exerted torque, and whether the knee angle affects the muscle activation–torque ratio. Nine healthy adult male participants participated in the study. They performed maximal voluntary isometric contraction (MVIC) at six (80°, 90°, 100°, 110°, 120°, and 130°) different knee joint angles (i.e., angles between the thigh and shin bones). Their maximal torque was assessed utilizing an isokinetic chair, while their muscle activation (root mean square [RMS]) was assessed using an eight-channel single differential surface EMG sensor. For the purposes of the torque–knee angle relationship and muscle activation–knee angle relationship, the torque and RMS were normalized relative to the maximal value obtained by each participant. To evaluate the muscle activation–torque ratio in function of knee angle, RMS was normalized relative to the corresponding torque obtained at each knee angle. Repeated measure analysis of va...

Comparison of generalised and directed co-contraction of knee joint muscles during four different movements to strengthen the quadriceps

2017

Background: The determinant role of different movements to strengthen the quadriceps on rate of knee joint co-contraction, hamstring to quadriceps muscle activity ratio and vastus medialis to vastus lateralis muscle activity ratio provides useful information for therapists, coaches and athletes about the role of each movement in the rehabilitation of patients with anterior cruciate ligament injury, osteoarthritis and patellofemoral pain syndrome. The aim of this study was to compare the rate of the generalised and directed co-contraction of knee joint muscles during free weights squat, smith machine squat, smith machine squat with one leg and the dead lift movements. Methods: 14 healthy power lifters (age: 26±7 years) were participated in this study.A portable EMG system with six pairs of bipolar surface electrodes was used to record the activity of the gastrocnemious medialis, long head of biceps femoris, semitendinosus, vastus lateralis, rectus femoris, and vastus medialis muscles...

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