van Oeijen K, Teunissen LL, van Leeuwen C, et al. - In this prospective observational study with the measurement at baseline, 6 months, 1 year, and 4 years, researchers described the course of performance of activities (observed and self-reported) of people (N = 92) with chronic idiopathic axonal polyneuropathy (CIAP) over 4 years and explored the connections with muscle strength, sensory function, and psychological personal factors (intention, perceived behavior control, and feelings of depression or anxiety). Walking was assessed utilizing the shuttle-walk test (SWT), a pedometer (mean step count/d), and the “physical functioning” subscale of the Short Form-36 questionnaire. Using a MicroFET handheld dynamometer and the Sensory Modality Sum score, muscle strength and sensory function were measured. Over time, the performance of activities of people with CIAP reduced (SWT, step count, physical functioning). This decline was associated with older age, loss of muscle strength, comorbidity, feelings of depression, and poor perceived behavior control. There were, however, substantial individual variations.