Stroke is one of the diseases with the highest mortality and disability rates worldwide. Spasticity is a motor disorder that affects more than 12 million people worldwide after stroke and is one of the most important causes of disability. Physiologically, spasticity affects the motor pathways of the brainstem and alters the excitability of motor neurons in the spinal cord, resulting in a reduction in the supraspinal-inhibitory-control mechanisms necessary for the regulation of the stretch reflex.

Spasticity is generally defined as "a motor disorder characterized by a speed-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyperexcitability of the stretch reflex as a component of the upper motor neuron syndrome". The muscle that develops spasticity creates a resistance to the movement during different movements and activities and makes it difficult to perform the movement. The resistance felt is due not only to neural causes, but also to peripheral causes (biomechanical factors such as soft tissue or muscle properties). Spasticity shows different characters at different speeds. The velocity-dependent increase in muscle tone is an important feature of spasticity. The stretching speed has obvious effects on the catching angle. However, the velocity dependence of spasticity may be partially dependent on joint angle position.

Spasticity, which occurs due to a structural and physiological anomaly, creates a disordered contractile behavior characteristic in the structures of the muscles it affects. Therefore, spasticity should be considered not only as a rehabilitated phenomenon, but also as a disrupted behavior pattern that should be suppressed. In spastic cases, lesion of the motor cortex and corticospinal tract is accompanied by loss of supraspinal inhibition. During activities such as standing and walking, spasticity leads to the activation of a synergistic pattern. Depending on the increase in the extensor tone of the upper extremities, flexor lower extremities, balance and gait problems occur in various degrees in patients. Spasticity reduces functional capacity, increases metabolic energy expenditure and causes disruptions in daily work. Considering the number of people affected by spasticity and functional disability caused by the neural and motor sequelae of the disease, it is of great importance to seek new forms of evaluation and treatment for the rehabilitation of affected patients.

Improving walking safety and speed and preventing falls are the main goals of gait rehabilitation for stroke survivors. For these reasons, the patient should be approached from a holistic point of view rather than the classical point of view in stroke rehabilitation. Hemiplegic gait is not the result of isolated skeletal muscle dysfunction seen after orthopedic disorders. Therefore, spasticity and spastic activation time should be considered in the treatment. Walking is not only a displacement activity; It should be considered as a concept that includes the simultaneous coordination of all the muscles that need to be active, providing the highest efficiency and quality with the least energy expenditure.

The spastic threshold rate is defined as the minimum rate at which spastic response is observed during controlled open chain measurements. It is estimated that the spastic threshold rate decreases as the severity of stroke increases in stroke patients. However, the relationship between the onset of stretch-induced muscle activation and the resistance (catching) felt by clinicians in stroke survivors has not been fully investigated. Also, it is not clear whether the catch angle also depends on the joint angle position. Spasticity is clinically related to speed, joint position, angle of capture, etc. should be revealed quickly, rehabilitation practices should be made specific to the person and the activity. By raising the spastic rate threshold, the emergence of spasticity in the early phase should be prevented, even at higher velocities. In the management of spasticity, with a current point of view, classical rehabilitation practices should be avoided and motor learning strategies specific to the patient should be introduced. In this sense, our study was planned to investigate the effect of speed-based motor learning training on spasticity characteristics and balance activities in stroke patients.