People with mild Parkinson's disease have impaired force production in upper limb muscles: A cross-sectional study.
Renee Salmon, Elisabeth Preston, Niruthikha Mahendran and 2 others
PMID 36266769WHAT IT FOUND
People with mild Parkinson's disease have significantly weaker upper limb muscles than healthy age-matched adults, averaging 78% of normal force.
Extensor muscles were the weakest. This deficit persists even when patients are physically active and on medication.
Key findings
01Force production was significantly impaired in all upper limb muscle groups except the wrist flexors when compared with controls.
02On average, participants with Parkinson's disease produced 78% of the force generated by healthy control participants.
03The most severely affected muscle groups were the extensors: shoulder (68% of control force), wrist (71%), and elbow (73%).
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study did not match groups for socio-economic status, which can influence health outcomes, though all participants were from a high socio-economic area. Participants did not complete a familiarization test prior to measurement, which could theoretically lead to submaximal effort, although the authors note no consistent improvement on the second attempt. Testing was performed only during the 'on' phase of medication, meaning the true functional deficit in daily life may be larger as patients spend time in the 'off' phase.
Declared interests
The authors declare no conflict of interest.
The easy way to misread this
Do not interpret these findings as evidence that strength training will reverse the deficit. The study identifies the presence and magnitude of weakness in mild Parkinson's disease but does not test any intervention. Additionally, the wrist flexors were not significantly weaker than controls, so the deficit is not uniform across all upper limb muscles.