Background and Purpose
The Maximum Step Length Test (MSLT), a measure of one’s capacity to produce a large step, has been studied in older adults, but not in people with Parkinson disease (PD). We characterized performance and construct validity of the MSLT in PD.
Methods
Forty participants (mean age: 65.12±8.20; 45% female) with idiopathic PD completed the MSLT while OFF and ON anti-PD medication. Construct validity was investigated by examining relationships between MSLT and measures of motor performance. The following measures were collected: Mini-BESTest, ABC scale, gait velocity, 6MWT, MDS-UPDRS III, and TUG. A repeated measures ANOVA tested for main effects of medication and stepping direction and the interaction between the two. Pearson or Spearman correlations were used to assess the relationships between MSLT and motor performance measures (α=0.05).
Results
Regardless of medication status, participants stepped further in the forward direction compared to the backward and lateral directions (p<0.001). Participants increased MSLT performance when ON-medication compared to OFF-medication (p=0.004). Regardless of medication status, MSLT was moderately to strongly related to Mini-BESTest, TUG, and 6MWT.
Discussion and Conclusions
People with PD stepped furthest in the forward direction when performing the MSLT. Increased MSLT performance was observed ON-medication compared to OFF-medication; however, the small increase may not be clinically meaningful. Given the relationships between the MSLT and the Mini-BESTest, 6MWT, and TUG, MSLT performance appears to associated with balance and gait hypokinesia in people with PD. Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1).