a + b: φ values for all the strides of the two minute walk are shown for a healthy adult (figure 2 a) and a patient (figure 2 b). PCI values are not dependent on the direction of deviation from the ideal 180° value (represented by solid line), i.e. higher or lower than 180°. Thus, group mean values of φ are close to 180° and are not statistically significantly different between the groups (Table 2), while φ_ABS, φ_CV, and thus PCI are highly increased in the patients. Healthy adult: mean number of steps/minute: 103; mean gait speed: 1.28 m/s. Stroke patient: mean number of steps/minute: 78.5; mean gait speed: 0.65 m/s.