Simulated work performance tasks in persons with neuropathic and myopathic weakness

Objectives: To determine the test-retest reliability of selected simulated work performance tasks in persons with neuropathic and myopathic weakness and control subjects, and the association between muscular performance during these work tasks and conventional isolated muscle group testing. Design: Measurement of three tasks performed on a work simulation device on two different days separated by 1 week. Associations between work task performance and previously reported strength measures in six muscle groups by hand-held dynamometry (HHD) were examined. Setting: Human performance laboratory of a university. Participants: Convenience sample of ambulatory outpatients with hereditary motor and sensory neuropathy, type I (n = 9), myotonic muscular dystrophy (n = 10), and able-bodied controls (n = 11). Main Outcome Measures: For work simulation, isokinetic peak torque and total work; and for HHD, maximal isometric torque. Results: Mean between-session differences for work simulation tasks ranged from -11% to +4% for peak torque and from -12% to +12% for total work; test sessions did not differ significantly for either patient or control groups. All groups had between-session intraclass correlation coefficients usually >.80, indicating good consistency. In general, correlations between peak torque during work simulation and HHD were strongest in the control group. Conclusion: Persons with neuromuscular weakness reliably performed the simulated work tasks examined in this investigation. Work simulation tasks may be a useful tool to assess muscular performance in persons with neuromuscular weakness.