Tetherball Paradigm – Tablet-Based Bilateral Training After Stroke

Many activities of daily living need both hands: tying shoes, preparing food, getting dressed. After a stroke, this coordination of both arms is often impaired. Conventional therapies, however, mostly train the affected arm alone. Bilateral upper limb training (BULT) is considered closer to everyday life, but it has depended on complex devices, and common clinical tests are often not sensitive enough to capture subtle differences in bilateral coordination.

THE METHOD

With the tetherball paradigm we developed a simple, tablet-based training. Users hold a tablet with both hands and tilt it rhythmically to guide a virtual ball on a tether along a circular path. This only works when both arms cooperate with fine timing and spatial coordination. Inertial sensors on the wrists record the movements of both forearms, so task performance, asymmetry and coordination can be measured objectively and at high resolution.

The method needs only a tablet and two sensors, which makes it highly accessible and easy to use.

PUBLISHED STUDY

In a study with 18 stroke patients and 18 healthy controls, we found significant differences in task performance, asymmetry and coordination characteristics. The method is therefore sensitive enough to capture even subtle differences in bilateral upper limb coordination.

Hwang, T.-H., Boltzmann, M., Jenner, S. B., Rollnik, J. D., Schmitz, G., & Effenberg, A. O. (2025). A Novel Bilateral Upper Limb Training Method for Stroke Rehabilitation. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 33, 4184 ff. https://doi.org/10.1109/TNSRE.2025.3614559 (open access)

ONGOING RESEARCH

In a single-blind randomized controlled trial (RCT) with 36 stroke patients, we compared the tetherball training with conventional unilateral training (10 training sessions over two weeks, with assessments before and after training and at follow-up). The manuscript is currently under review. We will report the results here once they are published.

PARTNERS

The studies were conducted in collaboration with the Institute for Neurorehabilitation Research (InFo), associated institute of Hannover Medical School, at the BDH-Clinic Hessisch Oldendorf.

CONTACT

Tonghun.Hwang@Sportwiss.Uni-Hannover.de
Alfred.Effenberg@Sportwiss.Uni-Hannover.de