Current study topics
Epimuscular myofascial force transmission
We have shown in contrast to the classical point of view that, transmission of muscular force does not occur via myotendinous junctions exclusively but a substantial part of muscle force is transmitted also via epimuscular myofascial pathways (i.e., via connections between neighboring muscular and non-muscular structures). The aim is to investigate the effects of epimuscular myofascial force transmission (see for detailed reviews Yucesoy Exerc Sport Sci Rev, 2010 and Yucesoy & Huijing J Electromygr Kinesiol, 2007) and its countless implications on e.g. orthopedic surgery, muscular diseases of genetic and overuse origin, motor control and mechanism of adaptation in muscle tissue. We use several different techniques including animal experiments, intra-operative human experiments, magnetic resonance imaging and finite element modeling.
Kinesio taping (KT) is extensively used among e.g., sportsmen for theraputic purposes. We aim at understanding the mechanism of KT effects by using advanced medical imaging analyses.
Cerebral palsy is a movement disorder caused by damage of the developing brain. Skeletal muscle spasticity is the central aspect of such disorders associated with exaggerated stretch reflexes caused by diminished inhibition. Increased resistance to stretch and muscle hypertonicity that commonly occur in the lower extremities cause children suffering from spastic cerebral palsy to walk with the hips and knees flexed and with equines deformity at the ankles.
We recently developed a methodology for testing muscular mechanics during orthopedic surgery. Findings obtained using such intra-operative testing have been very rarely reported, hence are quite unique. This kind of testing allows for quantifying spastic muscles’ potential for production of joint moment and joint movement. Testing of the spastic Gracilis muscle showed remarkably that it has no narrow operational joint range of force exertion and no supreme active resistance capacity to stretch at low length. Hence, the muscle shows no abnormal mechanics representative of joint movement disorder. Our current research is focused on identifying in what conditions such “normal” muscle function ceases.
Orthopedic remedial surgery
Aponeurotomy (transection of the intramuscular tendon sheet) is a surgical intervention performed frequently to correct restricted joint range of motion in e.g. spasticity. However, the mechanical mechanism of this operation is not well known. Using finite element modeling of muscle interfered the aim is to provide insight for such mechanism and to improve the success of the outcome. With animal experiments, we study the effects of aponeurotomy as well as dissections performed prior to this intervention (preparatory dissections) in a whole muscle compartment level. Our recent data show that aponeurotomy of target muscle affects also other muscles within the compartment despite being untouched. Therefore, our studies indicate that control of surgical outcome depends on a much broader viewpoint than just the target muscle.
Botulinum toxin type A (BTX-A) causes muscle paralysis and is applied to spastic muscles of cerebral palsy (CP) patients to decrease muscle tonus. As a consequence of decreased hyperactivity it is aimed at improving joint function and increasing joint range of motion. However, like in surgery, the mechanical mechanism of how BTX-A affects muscular function is not well known. On the other hand, BTX-A is highly diffusive and injection to one muscle causes paralysis in other muscles as well. We currently conduct animal experiments and finite element modeling to study intermuscular interactions and intramuscular mechanism of effects of BTX-A.
Magnetic resonance imaging
We use magnetic resonance imaging as well as diffusion tensor imaging modalities coupled with image processing techniques to assess muscular mechanics of human subjects, in vivo. This provides a unique opportunity to assess muscle function in health and disease.
Golgi tendon organs and muscle spindles are mechanoreceptors sensing muscle force and length changes. Our aim is the couple muscle force measurements with measurements from these sensors and assess the effects of epimuscular myofascial force transmission on such interaction. Studies indicate that the role played by such receptors is more complex than presently considered.