Fascicle Length Change of the Human Tibialis Anterior and Vastus Lateralis During Walking

Abstract

Amuscle's ability to produce force during a specific movement is determined by the type of muscle action (concentric, eccentric, or isometric). For example, based on the forcevelocity relationship of muscle, the muscle force decreases with increasing speed of movement during a concentric action, and the force increases during an eccentric action. Superimposing the force-velocity relationship on the length-tension relationship, the force will be optimal at a certain muscle (sarcomere) length during isometric and slow concentric actions. 22The use of kinematics and electromyography (EMG) to determine the type of muscle action assumes that the change in length of the muscle-tendon complex will reflect the change in length of the muscle t Study deSign: A single-group descriptive experimental design.t ObjectiveS: To determine the fascicle length change in the tibialis anterior (TA) and the vastus lateralis (VL) muscles during walking.t bAckgrOund: The length of the muscle fibers during isometric actions and during dynamic functional activities is affected by the compliance of the tendon and aponeurosis. The TA and VL muscles have important functions both in stance and swing phases of gait. Therefore, it is important to understand the dynamics of the muscle length change as it relates to the type of muscle actions in walking.t MethOdS And MeASureS: Nine healthy subjects performed treadmill walking while fascicle length, muscle activity (electromyographic signal), and joint angle (knee and ankle) were recorded. Fascicle length was measured using real-time ultrasound imaging. Fascicle length and joint angle during the gait cycle were analyzed using a repeated-measures analysis of variance.t reSultS: During the initial portion of stance, when the TA and VL muscles were active, the ankle plantar flexed and the knee joint flexed, suggesting muscle-tendon complex lengthening, but the fascicle length of both muscles remained constant (TA, P = .93; VL, P = .22). The TA muscle was again active during the initial portion of swing phase, while the ankle dorsiflexed, and the fascicle length decreased (P,.05). The VL muscle became active again at the end of swing as the knee extended, and the fascicle length decreased (P,.05).t cOncluSiOnS: The lack of change in fascicle length during the initial portions of stance phase suggests a nearly isometric muscle action of the TA and VL. There is a possible interaction occurring between the fascicle and tendon in the TA and VL such that the tendon lengthens to allow joint motion and potentially to store elastic energy.

Vastus Lateralis Fascicle Length Changes During Stair Ascent and Descent

“…In the weight acceptance phase of level walking the knee flexes about 12° and the fascicles lengthen minimally (0.25 cm). 3 This is in contrast to the significant shortening of the fascicles during the weight acceptance phase of stair ascent, in which the fascicles shortened 0.6 cm while the knee joint had essentially no movement. The difference in fascicle behavior between level walking and stair ascent may be a combination of the difference in knee joint angle change and the difference in the knee extension moment.…”

“…7 Whereas the VL tends to lengthen in the weight acceptance phase of gait and significantly lengthens during the knee flexion portion of the countermovement jump. 3,9,10 A similar discrepancy is evident when comparing the medial gastrocnemius and the VL during stair ascent and descent. The medial gastrocnemius fascicles remain at nearly constant length during stair ascent and shorten during weight acceptance in stair descent, compared to the VL fascicle shortening during ascent and lengthening during descent that occurs in the present study.…”

“…9 When walking on level ground, a less-intense activity, the VL fascicles did not lengthen significantly during knee flexion just after initial contact with the ground, suggesting that the tendon lengthens to allow knee flexion; however, the amount of knee flexion (12°) during this portion of gait was relatively small. 3 Despite VL fascicle lengthening during movements such as the drop jump, the fact that the tendon also lengthens suggests that the amount of fascicle lengthening may be limited.…”

“…The reliability of this method has been previously established with an ICC 3,1 of 0.90 and a coefficient of variation of 3.5%. 3 Foot switches were used to identify foot contact with the step. Four foot switches (Noraxon USA, Inc, Scottsdale, AZ) were placed on the plantar surface of the foot in the following positions: lateral aspect of the heel, the fifth metatarsal head, first metatarsal head, and the distal phalanx of the first digit.…”

“…2 Physical Therapist, Cleveland Clinic, Sports Health and Orthopaedic Rehabilitation, Cleveland, OH. 3 Physical Therapist, Ohio University Therapy Associates, Athens, OH. 4 Physical Therapist, Physiotherapy Associates, West Chester, OH.…”