An Electromyographic Study of Vastus Medialis Oblique and Vastus Lateralis Activity While Ascending and Descending Steps

Abstract

P atellofemoral pain is a common problem which affects a large number of athletic and nonathletic people. Symptoms frequently associated with patellofem* ral problems are generalized anterior knee pain, patellofemoral joint crepitus, peripatellar swelling, and buckling or locking of the knee (30). The symptoms are often exacerbated by prolonged sitting with a bent knee, rising from a seated position, ascending and descending stairs and sloped surfaces, and kneeling (7,8).The etiology of this problem could be related to nontraumatic factors, such a 5 osseous abnormalities, muscle imbalances, laxity o r tightness of the ligaments or joint capsule, or direct traumatic injury to the joint. The focus of the present study was on nontraumatic patellofemoral joint dysfunction, specifically muscle imbalances.The biomechanics of the patellofemoral joint are controlled by its static and dynamic components. The static components include the configuration of the articular surfaces, the medial and lateral retinaculum, and the patellofemoral and patellotibial ligaments. The primary dynamic components are the four parts of the quadriceps femoris complex with accessory input from the iliotibial band (lo), the adductor magnus and Ionof patellofemoral pain are I) neurogus (3,13), the pes anserine group, muscular imbalances of the vastus and biceps femoris ( 18,29). medialis oblique (VMO) and the vasSome of the theories for the etitus lateralis (VL), 2) tightness of the ology of nontraumatic gradual onset lateral knee retinaculum, hamstrings, Imbalances in the firing pattern and contraction intensity of the vastus medialis oblique (VMO) and the vastus lateralis (VL) have been considered important factors contributing to patellofemoral joint dysfunction. Vastus medialis oblique and vastus lateralis electromyographic (EMG) activity were measured for 15 individuals without patellofemoral pain (asymptomatic group) and 13 subjects with patellofemoral pain (symptomatic group) while ascending and descending steps. The peak V M O M ratios of EMG activity and the difference in peak VMO and VL onset times were measured. Two-way mixed-model analyses of variance (ANOVA) were used to determine the main effects of group (asymptomatic and symptomatic), phase (concentric phase ascending and two eccentric phases descending stairs), and the interaction between group and phase. The ANOVAs indicated no difference between groups for the peak V M O M EMG ratio or for the onset timing between peak VMO and VL muscle activity. Combining groups, the peak V M O M EMG ratio was less for the eccentric weight acceptance phase of descent compared with

Vastus Lateralis Fascicle Length Changes During Stair Ascent and Descent

“…However, only the stance phase of the gait cycle was analyzed during stair ascent and descent, because it is during stance phase that the vastus lateralis is most active in response to supporting body weight. 4,26 A clinical B-mode ultrasound imaging unit (Acuson 128XP; Siemens Medical Solutions USA, Inc, Malvern, PA) was used to obtain images of the VL muscle fascicles to determine fascicle length and pennation angle (5 MHz, 8-cm transducer). Real-time video output (30 Hz) from the ultrasound unit was transferred directly into a personal computer.…”

“…18 In addition, crucial for negotiating stairs. 4,26 Adequate knee extensor muscle function during stair climbing is a function of both neuromuscular and mechanical factors. While the neuromuscular factors have Experimental descriptive laboratory study.…”

Human patellar articular proportions: recent and Pleistocene patterns

“…More importantly, the average fibre orientation to the femoral diaphyseal axis for vastus lateralis obliquus is " 35m, whereas the fibre orientation for vastus medialis obliquus is " 47m (Farahmand et al 1998). This indicates that vastus medialis obliquus, in combination with electromyographic levels 20-100 % higher than those of vastus lateralis during normal locomotion (Reynolds et al 1983 ;Sheehy et al 1998), is in a position to both actively resist the lateral pull on the patella of portions of vastus lateralis and to act synergistically with the remainder of quadriceps femoris for patellar stability during locomotion (Reynolds et al 1983 ;Goh et al 1995 ;Farahmand et al 1998).…”

Cutaneous stimulation from patella tape causes a differential increase in vasti muscle activity in people with patellofemoral pain

“…For instance, studies measuring reflex latencies to a tap to the patella tendon only provide information on the latency of the stretch reflex [22] and do not provide information on how the activity of these muscles is controlled during functional activities. Other factors that influence the results include methods for detection of EMG onset (using computer algorithms or visual detection) and whether the onset of vasti EMG activity is expressed relative to each other or relative to mechanical events [33,36].…”