I am no doctor or physiotherapist but I have asked the physiotherapists running the classes why hydrotherapy helps myositis and this is what they had to say...
- It is effective in preventing further atrophy of the muscles
- It maintains the unaffected muscles you have
- It strengthens the unaffected muscles you have
- Relaxes muscles which can often tense up from pain
- Relieves pain and muscle spasms
- Increases circulation
- Increased joint range of movement
- Helps prevent shortening of the muscles from forming through stretching exercises that are held for 20 seconds or more
- Physiotherapists understand water physics, which include buoyancy, drag, depth and pressure, and can prescribe specific movements that can help individual conditions
- Buoyancy and heat of the water, means exercises, not possible on land, are possible
- The water temperature is effective for this therapy when it is kept at 34 to 35.5 degrees celsius
If you have any points you would like to add, or correct, please leave the details in the comments.
Here is a thorough article about exercise for myositis:
Exercise and Physical Therapy Guidelines for People with Myositis by
Hospital for Special Surgery in New York