A new study from Karolinska Institutet, published in eBioMedicine, shows that high-intensity interval training (HIIT) significantly boosts fitness and muscle endurance in people recently diagnosed with idiopathic inflammatory myopathies (IIM). This improvement is far greater than what traditional home exercise programs offer.
Understanding the Condition
IIM represents a group of rare autoimmune diseases that cause muscle weakness, fatigue, and reduced physical capacity. Although standard treatment combines medication with light to moderate home exercises, these interventions have shown limited effects on aerobic fitness. Therefore, researchers explored whether a more intensive training method could deliver better outcomes.
How the Study Was Conducted
The research team examined 23 patients recently diagnosed with IIM. They recruited participants from Karolinska University Hospital in Stockholm and Uppsala University Hospital. Next, they randomly assigned them to two groups. One group performed HIIT on a stationary bike three times a week for twelve weeks, while the other group followed a moderate-intensity home exercise program. Researchers assessed aerobic capacity, muscle endurance, and disease activity markers before and after the intervention.
HIIT Drives Stronger Improvements
As reported by medicalxpress, the results clearly favored HIIT. Aerobic capacity increased by an average of 16% in the HIIT group compared to just 1.8% in the home exercise group. Muscle endurance also improved more with HIIT. Moreover, muscle samples showed enhanced mitochondrial function, which plays a key role in cellular energy production. Importantly, disease activity remained stable in both groups, indicating that higher-intensity training is safe. The researchers found no evidence of increased inflammation or muscle damage.
Expert Insights
“Common symptoms of IIM include muscle weakness and reduced endurance. Our study shows that high-intensity interval training is safe and markedly improves muscle function and aerobic capacity,” said Kristofer Andreasson from the Department of Medicine, Solna, Karolinska Institutet. He added that better fitness may lower cardiovascular risk while helping patients gain stamina and independence. Therefore, HIIT could become a valuable complement to medication in improving physical capacity and quality of life.
Need for Further Research
Although the findings are promising, the researchers emphasize that this was a small study. Consequently, larger and longer-term studies are needed to confirm these results and understand the lasting effects of HIIT in IIM patients.