The figure-of-eight test captures balance deficits after stroke

Due to the increased stability demands of turning, the Figure-of-8 Test (F8T) may be a promising test to capture balance impairment after stroke. However, it remains unclear whether the F8T holds additional discriminative value after correcting for the influence of regular walking speed. This study evaluated the discriminative and construct validity of the F8T in people with stroke (PwS), accounting for the effects of walking speed. PwS with self-reported balance problems ( n = 20) and healthy individuals of similar age ( n = 20) performed the F8T, completing 4 laps around two hula hoops (d = 0.95 m) placed 3 m apart, both at comfortable and fast pace. Kinematics during the F8T were assessed using 3D motion capture. In addition, regular walking speed was obtained from a 2-minute walking test. Dynamic balance was evaluated using the miniBESTest. PwS showed a longer F8T time, larger center of mass trajectory length, longer turn duration, and less negative minimum mediolateral margin of stability compared to healthy individuals, both at comfortable and fast speed (all p’s < 0.001). These differences remained large and significant after correction for regular walking speed ( p < 0.009). MiniBESTest scores were only associated with F8T performance at fast pace, showing a moderate association with F8T time ( r =− 0.48, p = 0.031) and turn duration ( r =− 0.49, p = 0.029), and strong association with the minimum mediolateral margin of stability during turning ( r =− 0.60, p = 0.005). The F8T showed good discriminative abilities for balance impairment in PwS, even when corrected for the effects of a lower walking speed in PwS. The finding that PwS demonstrated less negative stability margins suggests that they adopted a more cautious movement strategy to avoid instability. Finally, the association between the F8T and the miniBESTest was only moderate to strong at fast pace, but should be interpreted in light of the relatively small sample size and limited range of balance problems within our stroke population.