Motor actions are governed by coordinated activation of mono- and biarticular muscles. This study considered differences in mono- and biarticular knee extensors between runners and cyclists in the context of adaptations to task-specific movement requirements. Two hypotheses were tested: 1) the length-at-use hypothesis, which is that muscle adapts to have it operate around optimal length; and 2)...

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...

The relation between shortening heat and sarcomere length was studied using fiber bundles from frog semitendinosus muscles as well as using whole muscles. The initial sarcomere length was varied between 2.0 and 3.66 micron. Shortening heat was estimated as the excess heat produced after a rapid isovelocity release in a 3 sec tetanus at 0 degrees C. The isometric control heat was measured in the...

We investigated the extent of mechanical interaction between rat flexor carpi ulnaris (FCU) and palmaris longus (PL) muscles following transfer of FCU to the distal tendons of extensor carpi radialis brevis and longus (ECRB/L) muscles. Five weeks after recovery from surgery, isometric forces exerted at the distal tendons of FCU and PL were quantified at various FCU lengths. PL was kept at a con...

The purpose of this research was to ascertain the relationship between architectures lower body muscles and lunges performance. Thirty recreationally active, untrained males (mean age: 17±1.25 years) were recruited participated in two testing sessions: anthropometrics muscle architecture, one-repetition maximum (RM) test. B-mode ultrasonography used assess thickness, pennation angle, fascicle l...

Tendon transfers commonly are used to restore arm and hand function after injury to the main motor nerves or after spinal cord injury. Surgeons traditionally use passive tension to determine the length at which a muscle should be attached during tendon transfer. The principles used to choose the length at which the transferred muscle should be attached still are relatively vague and have not be...

The female pelvic floor (PF) muscles provide support to the organs. During delivery, some of these have stretch up three times their original length allow passage baby, leading frequently damage and consequently later-life PF dysfunction (PFD). Three-dimensional (3D) ultrasound (US) imaging can be used image diagnose by assessing quantitative, geometric functional information through strain ima...

The purpose of the present study was to investigate muscle mechanical properties and mechanical interaction between muscles in the lower hindlimb of the spastic mutant rat. Length-force characteristics of gastrocnemius (GA), soleus (SO), and plantaris (PL) were assessed in anesthetized spastic and normally developed Han-Wistar rats. In addition, the extent of epimuscular myofascial force transm...

Skeletal muscles are length- and velocity-sensitive force producers, constructed of a vast array of sarcomeres. Muscles come in a variety of sizes and shapes to accomplish a wide variety of tasks. How does muscle design match task performance? In this review, we outline muscle's basic properties and strategies that are used to produce movement. Several examples are provided, primarily for human...

Skeletal muscles share many common, highly conserved features of organization at the molecular and myofilament levels, giving skeletal muscle fibers generally similar and characteristic mechanical and energetic properties; properties well described by classical studies of muscle mechanics and energetics. However, skeletal muscles can differ considerably in architectural design (fiber length, pi...