Photo Credit: DC Studio

The following is a summary of “Presence and origin of variability of the pull test and push-and-release test in people with Parkinson’s disease,” published in the March 2025 issue of Journal of Neurology by Jansen et al. 

Researchers conducted a retrospective study to examine the impact of within- and between-assessor variability on postural instability test outcomes in Parkinson’s disease (PD) and assess whether standardized treadmill-based mechanical perturbations improved test consistency.  

They evaluated 50 individuals with PD using a series of backward balance perturbations. Each participant underwent 3 repetitions of both the pull test and the push-and-release test, administered by 3 different assessors, resulting in 9 repetitions per test. Additionally, 5 standardized treadmill-induced perturbations were applied at 1.5 m/s² in a pseudo-random order.  

The results showed considerable within-assessor variability in both manual tests. A score difference of ≥2 points occurred in 30% of participants for the pull test and 42% for the push-and-release test. Variability was also observed between assessors, with inconsistent test delivery reflected in a wide range of sternum and center of mass displacements after the pull test and body inclination angles in the push-and-release test. In five repeated treadmill-based perturbations at 1.5 m/s², a ≥2 point difference was found in 18% of participants, with significantly greater consistency in sternum and center of mass displacements.  

Investigators concluded that inconsistent balance test scores resulted from variability in test administration and patient performance, suggesting standardized test delivery, like treadmill perturbations, could improve postural instability assessment. 

Source: link.springer.com/article/10.1007/s00415-025-12974-9#Abs1