Sequence of onset latency of body segments when turning on-the-spot in people with stroke

Abstract

Background: Turning around is a common activity of daily living. The location of a target may be known or unknown while angle and direction may vary prior to turning. A stroke can compromise coordination of body movement during turning.

Objectives: To investigate the effect of target predictability, turn angle and turn direction on the kinematic sequence of rotation of body segments in people with stroke and healthy controls when turning on-the-spot.

Methods: Ten people with stroke (age: 66±10 years; 8 males) and 10 age-matched controls (age: 65±8 years; 6 males) were asked to either turn to a specific light (predictable condition) or locate and turn to a random light (unpredictable condition) placed at 45°, 90° or 135° to the right or left when a light in front extinguished.

Results: People with stroke initiated movement of the segments significantly later than the controls (p=0.014). The sequence of onset of rotation of the segments was not different between both groups. Target predictability affected the sequence of the segments; the eyes, head and shoulder started moving simultaneously when turning to unpredictable targets while the head and shoulder started moving before the eyes when turning to predictable targets. The sequence was also different across the three turn angles for each predictability condition. However, the sequence remained the same when turning to both sides in each group.

Conclusion: Similarities between the groups may be because the time since the stroke was long and therefore some recovery of function may have occurred. Slowness of movement in people with stroke may predispose them to falls.

Keywords: Balance; Falls; Onset latency; Stroke; Turning.