Objective: We investigated the construct and ecological validity ON medication and the test-retest reliability both ON and OFF medication of the linear encoder lower extremity muscle peak power test in pwPD
Background: Persons with Parkinson’s disease (pwPD) experience impaired muscle function, possibly affecting their daily activities. Lower extremity muscle peak power is an important marker for physical function in pwPD. An easy-to-apply equipment that assesses peak power is a linear encoder which can be used in research and clinical practice. However, no study has investigated the validity and test-retest reliability (i.e., day-to-day variation) of the linear encoder lower extremity muscle peak power test in pwPD.
Method: Linear encoder data were collected while performing a sit-to-stand test. Construct validity (i.e. hypothesis testing of known groups validity) was assessed by comparing peak power from 69 pwPD and 35 healthy controls (HC). Ecological validity was evaluated by comparing associations between peak power and maximal force (Fmax) with walking performance (i.e., 6-minute walk test, Timed Up and Go test, and Six-Spot Step Test). Reliability was examined for 20 pwPD who completed 4 sit-to-stand tests (2 tests ON and 2 tests OFF medication), in a randomized order, separated by 5 to 11 days. Reliability was assessed as day-to-day variation and by intraclass correlation coefficients (ICC).
Results: Peak power was comparable between pwPD and HC (-1.1 W/kg; 95%-CI: -2.8;0.5). Stronger associations with functional performance were observed for peak power (r2=0.44-0.51) compared to Fmax (r2=0.25-0.29). Day-to-day variation was 1.0 and 1.3 W/kg and ICC2.1 was 0.95 (95%-CI: 0.87;0.98) and 0.93 (95%-CI: 0.82;0.97) ON and OFF medication, respectively.
Conclusion: The linear encoder lower extremity muscle peak power test is ecological valid but not construct valid ON medication and has an excellent day-to-day reliability ON and OFF medication.
To cite this abstract in AMA style:
F. Jensen, M. Langeskov-Christensen, L. Hvid, U. Dalgas. Validity and reliability of muscle peak power testing in persons with Parkinson’s disease [abstract]. Mov Disord. 2023; 38 (suppl 1). https://www.mdsabstracts.org/abstract/validity-and-reliability-of-muscle-peak-power-testing-in-persons-with-parkinsons-disease/. Accessed May 13, 2025.« Back to 2023 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/validity-and-reliability-of-muscle-peak-power-testing-in-persons-with-parkinsons-disease/