Tests to rule out other conditions might include: Electromyogram (EMG). Your doctor inserts a needle electrode through your skin into various muscles.
[mayoclinic.org]
For example, you may have difficulty climbing stairs or getting up from a chair.
[healthline.com]
Muscle weakness starts in one body part, such as the arm or hand, and slowly gets worse until it leads to the following: Difficulty lifting, climbing stairs, and walking Difficulty
[nlm.nih.gov]