PMID 41314147

Research
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High-intensity interval training outperforms moderate exercise to improve aerobic capacity in patients with recent-onset idiopathic inflammatory myopathies: a multicentre randomised controlled trial

Andreasson KM, Leijding C, Dastmalchi M, Notarnicola A, Gastaldello S, Yamada T, Sandlund H, Leonard D, Westerblad H, Lundberg IE, Andersson DC, Alexanderson H

Question

Is 12 weeks of high-intensity interval training more effective and still safe compared with clinical standard low-moderate intensity home-based exercise for improving aerobic capacity, muscle endurance, and mitochondrial function in patients with recent-onset idiopathic inflammatory myopathies?

Summary

This multicentre randomized controlled trial compared 12 weeks of HIIT with standard low-moderate intensity home-based exercise in 23 patients with recent-onset idiopathic inflammatory myopathies. HIIT used stationary-bike intervals, three sessions per week, progressing to six 30-second hard intervals with 2-minute moderate cycling rests, followed by one set of strength training. Compared with standard exercise, HIIT improved VO2peak, peak power, time to exhaustion, and mitochondrial protein expression without increasing serum muscle enzymes, disease activity, longstanding pain, fatigue, injuries, or falls. The findings are clinically relevant but come from a small, medically screened rare-disease sample with supervision and heart-rate monitoring.

Methodology

  • 23 adults with recent-onset idiopathic inflammatory myopathies, including polymyositis, dermatomyositis, and antisynthetase syndrome, excluding inclusion body myositis.
  • 23 participants.
  • Stationary-bike intervals plus one set of strength training for shoulders, knee extensors, and core.
  • Work intervals: 30 seconds.
  • Recovery: 2 minutes of moderate biking between intervals.
  • Intensity: At least 85% HRpeak during each interval; strength progressed when exertion was below 7 on Borg CR-10.
  • Interval cycling component approximately 15 minutes after progression, plus strength training; exact full duration not reported.
  • Three sessions per week.
  • 12 weeks.
  • Multicentre randomized controlled trial comparing HIIT with low-moderate intensity home-based standard-of-care exercise.
  • VO2peak, Peak power, Time to exhaustion, and Mitochondrial protein expression were tracked.

Outcomes

VO2peak

HIIT improved VO2peak more than control, both absolute and weight-adjusted.

VO2peak L/min increased 16% in HIIT versus 1.8% in control; between-group estimate 0.29 L/min (95% CI 0.10 to 0.47). VO2peak ml/kg/min between-group estimate 2.97 (95% CI 0.83 to 5.10).

Improved

Peak power and time to exhaustion

HIIT improved muscle endurance outcomes more than control.

Peak power increased 18% in HIIT versus 8% in control; between-group estimate 17.3 W (95% CI 3.9 to 30.8). TTE increased 23% in HIIT versus 11.25% in control; between-group estimate 1:42 (95% CI 0:06 to 3:18).

Improved

Mitochondrial adaptations

Muscle expression of mitochondrial respiratory chain complexes I and V, citrate synthase, and VDAC1 increased after HIIT but not control.

Paired tests within HIIT showed p<0.05 for selected mitochondrial proteins; biopsy analysis included HIIT n=7 and control n=6.

Improved

Disease activity and safety

HIIT did not increase group-level serum muscle enzymes or disease activity, and no longstanding pain, fatigue, injuries, or falls related to HIIT were reported.

MDAAT muscle disease activity between-group estimate -0.08 (95% CI -1.2 to 1.0); pain and fatigue showed no statistically significant worsening after HIIT.

No clear change

Insights

  • For selected clinical populations with very low aerobic capacity, a gradual ramp-up to short hard intervals can be feasible and effective when heart-rate monitored.
  • A 30-second work, 2-minute active recovery cycling structure at at least 85% HRpeak improved VO2peak and endurance in recent-onset IIM.
  • Clinical translation requires screening out serious contraindications and monitoring soreness, fatigue, pain, disease activity, and muscle enzymes.

Limitations

  • Small sample due to the rarity of IIM.
  • Missing data and incomplete paired biopsy samples.
  • COVID-19 restrictions changed eligibility timing and limited inclusion of higher-risk patients.
  • Some secondary outcomes may have been underpowered.
  • The trial does not show long-term maintenance beyond 12 weeks.
  • The protocol is cycle-ergometer based and not directly translatable to bodyweight-only HIIT.

Safety

  • No participants reported longstanding pain or fatigue, injuries, or falls related to HIIT.
  • HIIT participants reported delayed-onset muscle soreness for 1-2 days after each session.
  • HIIT participants reported instant muscle fatigue subsiding after about 30-60 minutes.
  • Serum CK, AST, and ALT did not increase after HIIT or control exercise.
  • LD remained slightly elevated in both groups at all time points but did not change, supporting no increased inflammation from exercise in the authors' interpretation.