Rather than long, cautious exercise routines, brief bursts of near-maximum effort may help improve strength and endurance without triggering the muscle inflammation doctors worry about most.
Everyday Life Shaped by Hidden Weakness
Inflammatory myopathies, including polymyositis and dermatomyositis, are uncommon but deeply disruptive. Simple actions like climbing stairs can feel exhausting, while carrying groceries may demand recovery time. Persistent fatigue and widespread pain gradually weave into daily routines.
These disorders fall under autoimmune diseases, where the immune system mistakenly attacks muscle tissue, creating ongoing inflammation. By diagnosis, many individuals have already lost a significant amount of muscle endurance. Research indicates stamina may be reduced by up to 70% compared with healthy peers of the same age.
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Even after months of standard therapy, full functional fitness often remains out of reach. Medications used to control immune activity, such as corticosteroids and immunosuppressants, can further weaken muscles and alter metabolism.
A major contributor lies in the mitochondria, the cell’s energy producers. In inflammatory myopathies, these structures operate inefficiently, leaving muscles short on energy during physical effort.
For years, patients were advised to avoid strenuous activity, based on fears that exercise could worsen muscle damage. Rest and very gentle movement became the norm.
Emerging evidence now questions that long-standing assumption, suggesting that properly structured intense training may not be harmful after all.
Testing High-Intensity Interval Training
Scientists at Sweden’s Karolinska Institutet explored whether high-intensity interval training (HIIT) could be both safe and effective for individuals newly diagnosed with inflammatory myopathy.
The study involved 23 adults, divided into two groups. One followed a traditional home-based programme focused on moderate exercise. The other completed a HIIT routine three times per week over a 12-week period.
The intense protocol was concise but demanding. Each session included:
- Six 30-second cycling sprints on a stationary bike
- Two minutes of light pedalling between each sprint
- Heart rate maintained above 85% of maximum during intense intervals
Participants were carefully supervised. Heart rate and perceived exertion were monitored, and intensity was adjusted individually. The goal was to push limits without crossing into unsafe territory.
Improved Fitness Without Increased Inflammation
The outcomes clearly favoured the HIIT group. Their aerobic capacity increased by 16%, compared with just 1.8% in those following moderate exercise.
Endurance also improved. Time to exhaustion rose by 23% in the HIIT group, versus a 12% increase with standard training.
Muscle tissue samples showed enhanced activation of mitochondrial proteins among HIIT participants, indicating improved energy production within muscle cells.
Most importantly, the intensified effort did not trigger disease flare-ups. Blood markers, clinical evaluations and patient feedback showed no rise in inflammation or muscle breakdown. Temporary soreness and fatigue were common but manageable and did not lead to withdrawal.
Rethinking Traditional Rehabilitation Advice
These findings challenge long-standing rehabilitation practices built around caution. Many patients with inflammatory myopathies are advised to avoid intense effort and follow extended, low-intensity routines.
The Karolinska research suggests that short, structured, high-intensity sessions can produce greater benefits in less time, without worsening the underlying disease.
Such sessions may also be more realistic for people already burdened by daily exhaustion.
Beyond muscle strength, improved aerobic fitness could help lower cardiovascular risk, which is elevated in chronic inflammatory conditions. Greater independence in daily activities may also reduce the psychological strain of long-term illness.
How Future Treatment Plans May Evolve
If confirmed in larger studies, HIIT could become part of standard care alongside medication. A future approach might include:
- Immunosuppressive medication to control autoimmune activity
- Supervised HIIT sessions to enhance endurance and mitochondrial function
- Light daily movement to maintain mobility and confidence
- Regular monitoring to track inflammation and adjust training safely
Medical approval and professional supervision would remain essential. Disease severity, heart health and lung function can vary widely between patients.
Common Questions Patients Ask
What does HIIT actually involve?
High-intensity interval training alternates short, demanding efforts with recovery periods. The intense phases are uncomfortable but brief, while rest intervals allow partial recovery.
For people with inflammatory myopathy, intensity is relative. A “sprint” simply means an effort that raises heart rate close to a safe maximum and makes talking difficult, while remaining controlled.
Why are mitochondria so important?
Mitochondria convert nutrients into usable energy. When they malfunction, muscles fatigue quickly and recover slowly. In inflammatory myopathies, this dysfunction compounds immune-related damage.
Higher-intensity training can stimulate mitochondrial growth and efficiency. The Swedish findings indicate this response still occurs despite autoimmune muscle disease, when exercise is carefully managed.
Real-World Impact on Daily Life
Consider someone newly diagnosed with polymyositis who struggles to walk short distances. Traditional rehabilitation might involve long, gentle sessions that often feel draining and unrewarding.
With a HIIT-based approach, total exercise time may be shorter but more focused. Over weeks, this can translate into walking farther without stopping or climbing stairs with less effort.
Risks remain. Excessive intensity too early can cause severe fatigue, joint pain or rare cardiac complications. This is why screening, gradual progression and open communication between patient and care team are critical.
When combined with appropriate medication and everyday movement, HIIT may offer cumulative benefits. Improved fitness can support mental wellbeing, sleep quality and treatment tolerance. For conditions once defined by rest and limitation, the inclusion of intense effort represents a meaningful shift in care.
