Dynamic Ultrasound of the Calf Muscles After Stroke

Muscle behaviour of calf muscles can be studied during dynamic conditions using dynamic ultrasound. In particular, the medial gastrocnemius is suitable for measurements with dynamic ultrasound due to its superficial location. With this measurement technique, the muscle behavior during walking can be observed gaining insight into the mechanism of action of this muscle during a functional task. This technique has already been used in other populations (such as children with cerebral palsy) but not yet in individuals after a stroke.

Therefore, the aim of this study is to assess the muscle behavior of the medial gastrocnemius during walking in persons after stroke. There are 3 concrete objectives of the current study:

1. is the technique feasible to perform in persons after stroke? 2. does the use of the dynamic echoprobe change gait patterns? 3. can differences between persons after stroke and healthy controls be detected? This data can be used as pilot data for project applications in the future that will allow to design larger studies.

Therefore, 10 stroke patients and 10 age- and gender-matched healthy controls will walk on a treadmill for 3x2 minutes after a familiarisation period of 6 minutes.

During 1 x 2 minutes, subjects will walk without using the dynamic ultrasound. This recording aims to measure the normal gait pattern of the subjects.

During the other 2x2 minutes, subjects will walk using the dynamic ultrasound at 2 different locations on the calf. Once with the ultrasound probe on the centre of the muscle belly to visualise muscle fibre bundles and once on the muscle tendon transition, from which muscle belly and tendon length can be derived.

The use of ultrasound or not will be randomized to exclude the effect of fatigue on the outcome measures.