Perceptions of effort during handgrip and tongue elevation in Parkinson's disease.

BACKGROUND Fatigue and the accompanying perception of effort are often heightened in Parkinson's disease. OBJECTIVES To compare performance on three sense-of-effort tasks between patients with PD and matched neurologically normal control subjects. METHODS Sixteen PD subjects and 16 normal subjects performed three tasks to assess sense of effort: self-ratings of effort using direct-magnitude estimation, generating pressures at various levels of effort, and sustaining a submaximal level of effort. The latter two tasks were done with handgrip and tongue elevation. RESULTS Two of the three tasks successfully differentiated the groups. Subjects with PD provided significantly higher ratings of effort for general daily activities and for speech. During the constant-effort task, pressure curves decayed more rapidly for the PD subjects. CONCLUSIONS Performance by PD subjects on the constant-effort task resembled that by normal adults who were pre-fatigued in previous experiments. Results support greater than normal sense-of-effort related to fatigue in PD, and provide preliminary validation of a performance-based physiologic task to assess abnormal sense of effort in this population.