The relationship between muscle length, integrated electromyographic activity, and torque of the biceps femoris muscle was investigated while the line of action of the muscle at the knee was held constant. Muscle length was changed by varying the hip joint angle. Sixteen subjects produced 1) maximal isometric contractions, 2) contractions with constant submaximal torque, and 3) contractions wit...

The physiological cross-sectional area (PCSA) of knee extensors (KE) and flexors (KF) was determined using magnetic resonance imaging (MRI) in humans. Twenty two healthy male volunteers were assigned to the subjects and MRI was taken to obtained 41•`52 consecutive axial images (slice thickness ;10 mm, interslice gap ; 0 mm) from right-leg thigh. From these images, anatomical cross-sectional are...

To safely land after a jump or hop, muscles must be actively stretched to dissipate mechanical energy. Muscles that dissipate energy can be damaged if stretched to long lengths. The likelihood of damage may be mitigated by the nervous system, if anticipatory activation of muscles prior to impact alters the muscle's operating length. Anticipatory motor recruitment is well established in landing ...

The feline anterior sartorius is a long strap-like muscle composed of short muscle fibers. Nerve branches that enter this muscle contain the axons of motor units whose constituent muscle fibers are distributed asymmetrically within the muscle. In the present study, twitch and tetanic isometric contractions were evoked by stimulating individual nerve branches while muscle force was recorded and ...

mercury and selenium concentrations were analyzed in the muscle and liver of milk shark (a dominant shark species in the persian gulf) from the coast of bandar abbas. a research project was designed to compare the level of accumulation hg and its interaction with se in milk shark. hg concentration for each sample was determined by an advanced mercury analyzer (leco, ama 254) and se was assayed ...

The region over which skeletal muscles operate on their force-length (F-L) relationship is fundamental to the mechanics, control and economy of movement. Yet surprisingly little experimental data exist on normalized length operating ranges of muscle during human gait, or how they are modulated when mechanical demands (such as force output) change. Here we explored the soleus muscle (SOL) operat...

Muscle fascicle lengths change as a function of muscle length and muscle force. The effect of these two factors may be balanced to maintain the same fascicle length at different joint angles during in vivo muscle function. The aim of this study was to determine the relationship between knee flexion angles, knee extensor torques and fascicle lengths of the Vastus Lateralis muscle. We found that ...

BACKGROUND during limb lengthening, muscles are thought to increase the number of sarcomeres. However, this adaptation may differ among muscles with diverse architecture. PURPOSE this study wish to clarify the differences in muscle adaptation in a rabbit model of tibial lengthening. METHODS twelve rabbits underwent tibial lengthening (0.7 mm/day for 4 weeks), with the contralateral limb ser...

Muscle fiber length is nearly uniform within a muscle but widely different among different muscles. We show that Abelson tyrosine-protein kinase 2 (Abl2) has a key role in regulating myofiber length, as a loss of Abl2 leads to excessively long myofibers in the diaphragm, intercostal and levator auris muscles but not limb muscles. Increased myofiber length is caused by enhanced myoblast prolifer...