In depth
Inflammatory myositis: common questions
The old advice was to rest a muscle disease, and the trials have been saying the opposite for some years now. The gains held at a year in the one long follow-up. Disease activity didn't stir anywhere in that time, and creatine kinase stayed where it was throughout.
What the research found.
One trial tested hard weight training in myositis, and the physical score on the SF-36, a general patient-reported quality-of-life questionnaire, rose by 5.33 points against controls. Muscle endurance rose by 11.49 points and muscle testing rose by 1.30, both on the same comparison. All three of those differences came out statistically significant in the trial report.
That trial reported no rise in disease activity at all, and creatine kinase didn't spike anywhere across the 16 weeks. At one year the endurance gain between the groups was 10.7 points on the Functional Index 3. The study puts the true gain somewhere between 2.2 and 19.1 points.
One review pooled the exercise trials in dermatomyositis and polymyositis. Strength improved at a standardized mean difference of 0.62 and aerobic fitness improved alongside it, which is a consistent direction. The evidence was still rated low certainty, because the samples going into that pooled figure were all small.
One blood test was notable for spotting the fast lung problem. That problem is the one that turns up in anti-MDA5 dermatomyositis, and the test is lactate dehydrogenase, which most people call LDH. The mean difference between groups was 75.94, and fever counted too, at an odds ratio of 3.16.
One guideline covers every adult going on long corticosteroids. That's the 2017 American College of Rheumatology guideline, and it strongly advises getting enough calcium and vitamin D. It advises weight-bearing and strength work, it advises stopping smoking, and it advises limiting alcohol, all of it at any adult age.
Exercising a muscle disease
For years people with myositis were told to rest, on the thinking that working an inflamed muscle would harm it further. The trials have now largely turned that thinking around. The strongest of those trials tested the thing that sounds least safe of all.
One trial tested hard weight training in myositis, and the physical score on the SF-36, a general patient-reported quality-of-life questionnaire, rose by 5.33 points between groups. Muscle endurance rose by 11.49 and muscle testing rose by 1.30, and all three differences were significant. Disease activity didn't rise and creatine kinase didn't spike over 16 weeks.
A one-year follow-up says the picture held, with the endurance gain between groups at 10.7 points and a P value of 0.01. The study puts the true gain between 2.2 and 19.1. Inside the training group, quality of life rose by 4.8 on the physical score and muscle testing rose by 1.8. Long follow-up is rare in rare disease research, and that's what makes this evidence worth leaning on.
What the wider evidence adds
One review pooled the exercise trials in dermatomyositis and polymyositis, where strength improved at a standardized mean difference of 0.62. Aerobic fitness improved too, and the review judged exercise safe. The certainty was rated low because the samples were small, which is a limit recurring through every rare disease literature on this site.
A second review looked at supervised physical therapy in both polymyositis and dermatomyositis, which is a different question again. It found better function, and safety held across several study designs. So across the three sources the direction is consistent, while the sizes rest on small numbers.
Here's how to read all of that together. The fear about exercise here has been tested and it wasn't supported, and every program tested was supervised. Those two facts belong together rather than apart. The evidence takes away the belief that training damages the muscle, and it doesn't take away the need for an assessment of what you can manage now.
Creatine kinase, and what a rise means
Creatine kinase is the blood test people tie to this disease, and it's also why many are afraid to exercise. One trial looked directly at the question of hard training. There was no creatine kinase spike anywhere across the whole 16 weeks of it.
Two things make a single high reading hard to interpret. Creatine kinase rises after any unusual effort, including in people with no muscle disease at all. It also varies between people for reasons that have nothing to do with inflammation, so a number on its own can't tell a muscle working hard from a muscle under attack.
That's an argument for mentioning a rise rather than an argument for ignoring it or for panic. The people managing your disease can put a reading next to your symptoms, your exam, and what you've been doing. That context is what makes the number useful to anybody.
The lung complication that changes the calculation
Scarring in the lungs is a known part of this disease group, which is why breathlessness here deserves less benefit of the doubt than in most conditions. In anti-MDA5 dermatomyositis there's a fast-moving form of it. That form kills a high share of the people who get it.
One analysis pooled what predicts it, and lactate dehydrogenase was notable among the blood tests. People call it LDH, the mean difference was 75.94, and the study puts the true difference between 64.20 and 87.67. Other tissue markers were weaker, with AST at 24.35 and ALT at 26.20. Among the clinical signs, fever gave an odds ratio of 3.16, and anti-Ro-52 counted too.
Our record for that paper says the full text is worth getting, and it calls it the highest-stakes item in the myositis sources. What it supports here is one practical message. New or worse breathlessness, or a new cough, means being seen promptly rather than waiting for your next routine visit.
Diet, where the field is empty
No food trial has been run in myositis, and that absence is real rather than a hole in this site's reading. So any diet advice given for this diagnosis is borrowed from somewhere else. The borrowing usually goes unmentioned by whoever is doing it.
Two things come up in general talk for good reason. This disease wastes muscle, which makes protein sound relevant, and long corticosteroid treatment makes vitamin D and calcium relevant. Neither has been tested here, and the second reaches you anyway through the corticosteroid guideline.
That guideline is the firm thing you have, and it covers every adult going on long corticosteroids. The 2017 American College of Rheumatology advice is to get enough calcium and vitamin D, do weight-bearing and strength work, stop smoking, and limit alcohol. It's a strong recommendation at every age, and it applies whatever put you on the drug.
Common misconceptions.
Myth. Exercising a muscle disease will damage the muscle.
Reality. That was the old advice and the trials don't back it. One trial tested hard weight training, where disease activity didn't rise, creatine kinase didn't spike over 16 weeks, and strength, endurance, and quality of life all improved. A one-year follow-up showed the endurance gains held, and the safety picture didn't change.
Myth. A rising creatine kinase after exercise means damage.
Reality. One trial looked at this directly, and hard weight training produced no creatine kinase spike over 16 weeks. Creatine kinase also rises after any unusual effort, including in people with no muscle disease at all, so one reading is hard to read on its own. Take a rise to the team managing your disease, because working out what caused it is their job and there are several candidates.
Myth. There's a diet for myositis.
Reality. No food trial has been run in this disease. So any diet advice offered for myositis is borrowed from another disease or from general food writing, and the borrowing usually goes unmentioned. What does apply is the corticosteroid guideline, and that reaches you through your treatment rather than your diagnosis.
Myth. Breathlessness in myositis is only being unfit.
Reality. This is the symptom that deserves the least benefit of the doubt here. Lung scarring is a known and serious part of this disease, and in anti-MDA5 dermatomyositis there's a fast-moving form that kills a high share of the people who get it. One blood test was notable for spotting it, which is LDH at a mean difference of 75.94, and fever counted too at an odds ratio of 3.16.
Questions patients ask.
Is it safe to exercise with myositis?
The trials say yes, and that holds even for hard training. One trial tested hard weight training, where disease activity didn't rise and creatine kinase didn't spike over 16 weeks. The physical score on the SF-36, a general patient-reported quality-of-life questionnaire, rose by 5.33 points between groups, muscle endurance rose by 11.49, and muscle testing rose by 1.30, all significant.
Do the gains last?
A year of follow-up says that they mostly do. The endurance gain between groups was 10.7 points at one year, on a true gain the study puts between 2.2 and 19.1, at a P value of 0.01. Inside the training group, quality of life rose by 4.8 on the physical score and muscle testing rose by 1.8. A year is a long follow-up for an exercise trial in a rare disease.
What does the wider evidence say?
One review pooled the exercise trials in dermatomyositis and polymyositis, where strength improved at a standardized mean difference of 0.62. Aerobic fitness improved too and the review judged exercise safe, though it rated the certainty low because the samples were small. That's the recurring problem in rare disease research. A second review looked at supervised physical therapy and found better function, with safety holding across several study designs.
Should I worry if my creatine kinase goes up?
It's worth mentioning without being automatically a sign of damage. The hard training trial found no creatine kinase spike over 16 weeks, and creatine kinase also rises after any unusual effort, including in people with no muscle disease at all. So one reading is hard to read on its own, which is why you take it to your team rather than deciding yourself what caused it.
Is there a diet for myositis?
No, and that absence is real rather than a hole in our reading. No food trial has been run in this disease at any point. Protein and vitamin D still come up in general talk for a reason, because this disease wastes muscle and corticosteroids make vitamin D more relevant. Neither has been tested here, so anything firm you're offered is borrowed from another disease.
What applies to me because I'm on corticosteroids?
The 2017 American College of Rheumatology guideline does, and it applies to any adult going on long corticosteroids at any age. Get enough calcium and vitamin D, do weight-bearing work, stop smoking, and limit alcohol. That reaches you through your treatment rather than your diagnosis, and it covers most people with this disease.
What is the lung complication I keep reading about?
It's scarring in the lungs, and it's a known and serious part of this disease group. In anti-MDA5 dermatomyositis there's a fast-moving form that kills a high share of the people who get it. One blood test was notable for spotting it, which is LDH at a mean difference of 75.94, with AST at 24.35 and ALT at 26.20. Fever gave an odds ratio of 3.16, so new or worse breathlessness isn't something to watch and wait on.
How should I start exercising?
With help from somebody who has seen this disease, and from where you are now. The trials all used supervised programs, and the hard one that got the best numbers was watched closely. That's a different thing from deciding to train hard alone. What the evidence takes away is the fear that training harms the muscle, and it doesn't take away the need for an assessment of what you can do today.
What should I take to my next appointment?
Any change in your breathing, a new cough, trouble swallowing, and the exact tasks that got harder. Stairs, getting out of a chair, and reaching overhead are the telling ones, because those show weakness in the muscles closest to your trunk. They tell your team more than a general sense of being weaker does. Mention breathlessness promptly, because a routine visit may be weeks away and this is not a symptom to hold.
References.
- Jensen KY; Aagaard P; Suetta C et al. High-intensity resistance training improves quality of life, muscle endurance and strength in patients with myositis: a randomised controlled trial. Rheumatology international. 2024;44:1909-1921. 10.1007/s00296-024-05698-yRCT
- Jensen KY; Aagaard P; Suetta C et al. High-intensity resistance training in patients with myositis - 1-year follow-up on a randomised controlled trial. Rheumatology international. 2025;45:104. 10.1007/s00296-025-05858-8RCT follow-up
- da Silva BISL; Dos Santos BRJ; Carneiro JA et al. Physical exercise for dermatomyositis and polymyositis: a systematic review and meta-analysis. Clinical rheumatology. 2022;41:2635-2646. 10.1007/s10067-022-06281-1SR + MA
- Corrado B; Ciardi G; Lucignano L. Supervised Physical Therapy and Polymyositis/Dermatomyositis—A Systematic Review of the Literature. Neurology International. 2020;12:77-88. 10.3390/neurolint12030015SR
- Liu T; Ji X; Wei Y et al. Predictors of rapidly progressive interstitial lung disease in anti-MDA5 dermatomyositis: a meta-analysis. Rheumatology (Oxford, England). 2026;65. 10.1093/rheumatology/keag311Systematic review and meta-analysis of 27 cohorts
- Buckley L; Guyatt G; Fink H et al. 2017 American College of Rheumatology Guideline for the Prevention and Treatment of Glucocorticoid‐Induced Osteoporosis. Arthritis & Rheumatology. 2017;69:1521-1537. 10.1002/art.40137GRADE-based clinical practice guideline
This page gathers the published research on this subject into one place. The studies behind it were published between 1989 and 2026, and every figure links to the paper it came from. Those studies were peer reviewed. This summary of them was not. Dr. Sarah Luebker is reviewing these pages one at a time and has not reached this one yet, so it carries no medical review date and nothing here is her opinion or her advice to you. Each page gets updated as she reaches it. It is here in the meantime because the science is worth having in one organized place that is easy to find and easy to read. Talk to your own clinician before acting on any of it.