A 12-week high-intensity interval training and strength exercise program may significantly improve cardiovascular health and physical fitness in patients with rheumatoid arthritis, according to a new study.
In the randomized controlled trial, published in the British Journal of Sports Medicine, researchers randomly assigned 87 patients with well-controlled rheumatoid arthritis (RA) (86% female, mean age 48 years) to either a 12-week supervised high-intensity interval training (HIIT) and strength training program (n = 43) or a control group instructed to maintain moderate physical activity (n = 44).
The intervention group participated in twice-weekly supervised sessions combining HIIT on cycle ergometers (4 x 4-minute intervals at 90% to 95% maximum heart rate) with strength training of major muscle groups. They also completed one unsupervised aerobic session per week at 70% maximum heart rate.
Among the key findings after 12 weeks were:
- Mean difference in VO2max between groups: 3.71 mL/kg/min (95% confidence interval [CI] = 2.16–5.25, P < .0001)
- Mean difference in O2 pulse: 1.38 mL/beat/min (95% CI = 0.85–1.91, P < .001)
- Mean difference in waist circumference: –2.6 cm (95% CI = –5.09 to –0.18, P = .035)
- Mean difference in 1-minute sit-to-stand test: 5.0 repetitions (95% CI = 3.35–6.72, P < .001)
- Mean difference in handgrip strength: 28.5 N (95% CI = 3.80–52.8, P = .021)
- Mean difference in overall health (VAS-Global): –14.7 (95% CI = –23.8 to –5.50, P = .001).
There were no statistically significant differences between groups in pain (mean difference = –4.0, 95% CI = –13.07 to 5.06, P = .38) or disease activity as measured by DAS28 (mean difference = –0.25, 95% CI = –0.60 to 0.10, P = .16).
The 3.71 mL/kg/min improvement in VO2max corresponded to an 11% increase in the intervention group. Previous research has associated each 3.5 mL/kg/min increase in VO2max with a 12% to 13% reduction in all-cause mortality risk.
The study participants had a mean disease duration of 6.1 years (standard deviation [SD] = 4.58) in the intervention group and 6.9 years (SD = 5.37) in the control group. Baseline DAS28 was 2.0 (SD = 0.90) in both groups, indicating low disease activity or remission. Baseline VO2max was 26.2 mL/kg/min (SD = 5.3) in the intervention group and 26.4 mL/kg/min (SD = 6.5) in the control group.
The HIIT protocol consisted of a 10-minute warm-up at 60% to 70% HRmax, followed by 4 x 4-minute intervals at 90% to 95% HRmax with 3-minute active recovery periods at 70% HRmax between intervals, and a 3-minute cool-down at 60% to 70% HRmax.
Strength training progressed from 50% to 60% of 1 repetition maximum (1RM) in weeks 1 to 2 to 70% to 80% 1RM by weeks 7 to 12.
Additional secondary outcome results included:
- Mean difference in VO2 (mL/min): 260.6 (95% CI = 168.5–351.5, P < .001)
- Mean difference in VEmax (L/min): 6.73 (95% CI = 1.21–12.20, P = .016).
No statistically significant differences were observed in resting blood pressure, lipid profiles, or inflammatory markers (ESR, CRP).
The Patient Global Impression of Change (PGIC) showed that 78% of the intervention group reported "very much to minimally improved symptoms" compared with 11% of the control group (P < .0001).
Per-protocol analysis for patients attending ≥ 70% of supervised sessions showed a mean difference in VO2max of 4.1 mL/kg/min (95% CI = 2.43–5.77, P < .0001).
Intervention participants attended an average of 19 (SD = 6.0) supervised sessions and 12 (SD = 3.6) unsupervised sessions over 12 weeks. Thirty-three patients (77%) completed ≥ 70% of supervised sessions.
One patient experienced irregular heart rate during HIIT and completed the intervention at moderate intensity following cardiac evaluation. Four patients had temporary increased musculoskeletal pain managed with exercise modification. One patient discontinued strength training as a result of persistent pain. Two patients received corticosteroid injections during the intervention period. No serious adverse events were reported.
An exploratory interaction analysis revealed that men had the highest potential to improve VO2max in the study.
The study had several limitations, including a predominantly female sample (86%), short 12-week intervention duration, lack of long-term follow-up, no reporting of self-administered physical activity in the control group, and use of sit-to-stand test rather than direct strength assessment.
The authors declared having no competing interests.