In depth
MCTD / overlap: common questions
A European reference network searched for care guidelines in mixed connective tissue disease and found no guideline at all. So everything you get offered here is borrowed from a nearby illness. Knowing that changes how much weight to give any of it, which is why the page opens with it.
What the research found.
A European reference network searched for care guidelines in mixed connective tissue disease. It found no guideline at all, so it read guidelines written for other connective tissue diseases, looking for parts that might apply here. That's what the field does here in place of a guideline of its own.
One group exercised through six weeks of high-dose corticosteroids for connective tissue disease. Their muscle mass fell 5.5 percent and their knee strength fell 9.7 to 11.6 percent. Two fitness measures rose all the same, one of them by 13.0 percent and the other by 9.0 percent.
Nagashima and colleagues, European Journal of Applied Physiology, 2021
The 2017 American College of Rheumatology guideline covers every adult on a long corticosteroid course. It strongly advises four things, and those are getting calcium and vitamin D right, doing weight-bearing and strength-building exercise, stopping smoking, and cutting back on alcohol. That advice reaches a reader through their treatment rather than through their diagnosis.
No guideline exists, and somebody checked
A European reference network set out to find care guidelines for mixed connective tissue disease. Its search came back empty, so it read guidelines written for other connective tissue diseases instead, looking for parts that might apply here. That's the first fact about this illness worth having.
That work produced three jobs for future guidelines, which are how to make the diagnosis, what to check at the start and over time, and treatment. Patients who took part listed their own priorities as well. Two of those were getting an early diagnosis and having basic counts of how common the illness is.
So when somebody gives you advice about this illness, it comes from guidelines written for lupus, systemic sclerosis, myositis, or rheumatoid arthritis. A doctor applies them using judgment, which is fair practice. What's worth knowing is that this is what's happening, because this illness overlaps those diseases without being any of them.
What is known about exercise capacity
No trial of exercise in mixed connective tissue disease exists anywhere. One study comes close to it and that study isn't in this disease alone, so read it with that firmly in mind. There's a second reason for care as well.
This illness overlaps lupus, systemic sclerosis, and myositis without being any one of them. So a finding in a mixed group of connective tissue disease patients may or may not describe you at all. The work that would settle the question either way has never been done.
That study followed people exercising through a high corticosteroid course for connective tissue disease broadly. Over six weeks their muscle mass fell 5.5 percent and their knee strength fell 9.7 to 11.6 percent, while two fitness measures rose, by 13.0 percent and 9.0 percent. The record here adds that how many of those people had this exact diagnosis couldn't be confirmed.
What that corticosteroid study suggests
Read carefully, those figures say something quite specific. Exercise did better at guarding fitness than at guarding muscle during a high corticosteroid course, with muscle mass and strength both falling while the two fitness measures both rose. One set of people, over one stretch of six weeks, and that's the whole finding.
That's worth knowing before you start a program expecting to hold your muscle through a course of treatment. It doesn't argue against exercising at all, and it never has done. It argues against being let down when the scales and the strength numbers refuse to cooperate with you.
Confidence intervals and P values couldn't be retrieved for any one of those figures. So this page reports them as percentage changes and nothing beyond that. That's the level of precision the checking behind this site supports, and the page won't go past it.
The one recommendation that does apply
Most people with this diagnosis take corticosteroids at some point in the course of it. That brings along a guideline of its own, which is the 2017 American College of Rheumatology guideline, covering every adult on a long course. It strongly advises calcium and vitamin D, weight-bearing and strength-building exercise, stopping smoking, and drinking less.
That's the most specific lifestyle advice anybody with this illness can get, and it comes through the drug rather than through the disease. Weight-bearing and strength-building are the useful words in it. They tell you which kind of work to do rather than leaving you to guess at one.
Past that, no trial of any diet exists anywhere in this illness. The source set here holds one study of vitamin D levels in a large group with this disease, and its numbers couldn't be retrieved to check them. So this page quotes not one of them rather than guessing at any.
Living with a diagnosis that has no map
Here's the practical result of a missing guideline, and it's worth stating plainly. More rides on your individual doctor than it would in a commoner disease, so three things follow from that. Stay with one team where you can, ask what a recommendation is based on, and treat confident advice with the doubt the reference network applied.
It's also a reason to mention a change anywhere rather than filtering it out first. This disease overlaps lupus, systemic sclerosis, and myositis, so the lungs, the kidneys, the muscles, the skin, and the blood vessels are all in play. A symptom that seems to have nothing to do with your joints may have everything to do with your illness.
The most useful things to bring to an appointment are the specific ones. New shortness of breath or a new cough, trouble swallowing, cold-triggered finger attacks, and any sore on a fingertip all belong there. So do the particular tasks that have got harder, because stairs and getting out of a chair say more than a general description of being tired.
Common misconceptions.
Myth. There are guidelines for this disease somewhere.
Reality. There aren't any, and a European reference network searched without finding one for this disease. So it read guidelines written for other connective tissue diseases, looking for parts that might apply, and it set out three jobs for future guidelines. Those are how to make the diagnosis, what to check at the start and over time, and treatment.
Myth. Advice for lupus applies to me directly.
Reality. It's what gets used, because there's nothing else available. The reference network was plain about that, and borrowing is what the field does, which is a different thing from saying the borrowing has been checked. This disease overlaps lupus, systemic sclerosis, and myositis without being any of them, so knowing the advice is borrowed changes how much weight to give it.
Myth. Exercise will maintain my muscle through steroid treatment.
Reality. It may not, on the one study that looked. One group exercised right through a high corticosteroid course, and their muscle mass still fell 5.5 percent over six weeks while their knee strength fell about 10 percent. Their fitness measures rose over that stretch, by 13.0 and 9.0 percent, so exercise seems to guard fitness better than muscle at high doses.
Myth. Reduced exercise capacity must mean my heart or lungs are affected.
Reality. It might mean that, and it might not. Muscle weakness produces the identical feeling, and a corticosteroid course is one thing that causes it. No study held here is strong enough to tell you which of the two is commoner, so the point is to get it checked rather than assumed, and new shortness of breath in particular belongs in an appointment.
Questions patients ask.
Are there guidelines for mixed connective tissue disease?
No, and a European reference network searched without finding one. So it read guidelines written for other connective tissue diseases, looking for parts that might apply here, and it set out three jobs for future guidelines. Those are how to make the diagnosis, what to check at the start and over time, and treatment. Patients who took part listed their own priorities, and two of those were an early diagnosis and basic counts of how common the illness is.
So where does my treatment advice come from?
From guidelines written for other diseases, which are lupus, systemic sclerosis, myositis, and rheumatoid arthritis. A doctor applies them using judgment, which is a fair way to work in a rare disease with no guideline of its own. This illness overlaps those diseases without being any of them, so the borrowing isn't straightforward.
What's known about exercise here?
Very little is known, and nothing in this disease alone. The nearest thing followed people with connective tissue disease of various kinds exercising through a high corticosteroid course. The record here can't confirm how many of them had this exact diagnosis, so what this page gives you is borrowed rather than direct, and it says so rather than hiding it.
Does exercise help during steroid treatment?
One study followed people exercising through a high corticosteroid course for connective tissue disease. Over six weeks their muscle mass fell 5.5 percent and their knee strength fell 9.7 to 11.6 percent, while two fitness measures rose, by 13.0 percent and 9.0 percent. The record here adds a caution, because how many of those people had this exact diagnosis couldn't be confirmed.
Why is my exercise capacity so low?
There are several possible reasons and no study in this disease strong enough to rank them. Muscle weakness is one of them, and a corticosteroid course is one cause of that. Lung trouble is another, and it's known across the diseases this one overlaps, so it's worth having looked at properly and early.
Is there a diet for this condition?
No trial of any diet exists in this disease. The source set here holds one study of vitamin D levels in a large group with this diagnosis, and its numbers couldn't be retrieved to check them, so this page quotes not one of them. What does apply reaches you through your treatment, because anybody on a long corticosteroid course falls under the 2017 American College of Rheumatology guideline.
What does the steroid guideline say?
It covers every adult starting or staying on a long corticosteroid course, at every age. It strongly advises getting calcium and vitamin D right, doing weight-bearing and strength-building exercise, stopping smoking, and cutting back on alcohol. That's the most specific lifestyle advice anybody with this diagnosis can get, and it reaches you through the drug rather than the disease.
Why is there so little research?
Three reasons, and the first is that the disease is rare. Its definition overlaps several others, which makes finding trial patients hard, and research money follows the commoner illnesses. The reference network did its work because somebody recognized that hole, and what came out was a list of what needs doing rather than a set of answers.
What should I take to my next appointment?
Four things, and the first is new shortness of breath or a new cough. Trouble swallowing is the second, and any change in your fingers is the third, which covers cold-triggered attacks and any sore on a fingertip. The fourth is the specific tasks that have got harder, because stairs and getting out of a chair show weakness near the trunk better than saying you feel tired.
References.
- Chaigne B; Scirè C; Talarico R et al. Mixed connective tissue disease: state of the art on clinical practice guidelines. RMD Open. 2018;4:e000783. 10.1136/rmdopen-2018-000783Systematic literature review for clinical practice guidelines
- Nagashima M; Takahashi D; Mizushima T et al. Effects of exercise in patients with connective tissue disease receiving high-dose glucocorticoids: a pilot prospective cohort study. Eur J Appl Physiol. 2021;121:2253-2263. 10.1007/s00421-021-04697-2Pilot prospective cohort study
- van der Net J; Wissink B; van Royen A et al. Aerobic capacity and muscle strength in juvenile-onset mixed connective tissue disease (MCTD). Scand J Rheumatol. 2010;39:387-392. 10.3109/03009741003742714Cross-sectional observational study of aerobic capacity and muscle strength in juvenile-onset MCTD
- Hajas A; Sandor J; Csathy L et al. Vitamin D insufficiency in a large MCTD population. Autoimmun Rev. 2011;10:317-324. 10.1016/j.autrev.2010.11.006Observational study of vitamin D status in a large MCTD cohort
- 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.