Ten weeks of high-intensity interval walk training is associated with reduced disease activity and improved innate immune function in older adults with rheumatoid arthritis: a pilot study
Question
Is 10 weeks of supervised high-intensity interval walking associated with improved disease activity, aerobic fitness, innate immune function, and systemic inflammatory markers in older adults with stable rheumatoid arthritis?
Summary
In a small uncontrolled pilot study, 12 sedentary older adults with stable rheumatoid arthritis completed 10 weeks of supervised treadmill-based high-intensity interval walking. Attendance was very high, cardiorespiratory fitness increased by about 9%, resting heart rate and mean arterial pressure improved, DAS28 disease activity scores fell, and several neutrophil and monocyte antibacterial function measures improved. Because there was no non-exercise control group, the study is useful but cannot isolate the intervention effect with high certainty.
Methodology
- Sedentary older adults with confirmed stable rheumatoid arthritis.
- 12 participants.
- Supervised treadmill walking with speed and incline adjustments.
- Work intervals: 60-90 seconds at HR corresponding to 80-90% VO2 reserve.
- Recovery: Similar-duration active recovery at 50-60% VO2 reserve.
- Intensity: Prescribed HR from VO2 reserve; actual high-intensity HR percentage 85 +/- 5%; RPE recorded after each high-intensity bout.
- 30 minutes including 5-minute warm-up and 5-minute cool-down.
- 3 sessions per week.
- 10 weeks.
- Single-arm supervised pilot intervention with pre/post assessments.
- Disease activity, VO2peak, Resting blood pressure and heart rate, and Physical function were tracked.
Outcomes
VO2peak
VO2peak improved from 1.75 +/- 0.4 to 1.89 +/- 0.4 L/min and from 25.0 +/- 6.6 to 27.1 +/- 7.0 ml/kg/min, described as about a 9% increase.
Both absolute and relative VO2peak p<0.001; effect sizes d=2.86 and d=3.19.
Disease activity
DAS28ESR decreased from 3.1 +/- 1.6 to 2.3 +/- 1.2 and DAS28CRP from 3.1 +/- 1.2 to 2.4 +/- 1.0; swollen joints, global health, and ESR also improved.
DAS28ESR p=0.001, d=1.23; DAS28CRP p=0.001, d=1.26; swollen joints p=0.013; global health p=0.037; ESR p=0.023.
Resting cardiovascular measures
Resting heart rate fell from 69 +/- 8 to 64 +/- 8 beats/min and mean arterial pressure from 94 +/- 11 to 89 +/- 9 mmHg; systolic and diastolic BP trends did not reach conventional significance.
Resting HR p=0.009, d=0.91; MAP p=0.044, d=0.66; systolic BP p=0.070; diastolic BP p=0.064.
Physical function
400-m walk time improved and 30-second chair stands increased, while other function measures were not significantly changed.
400-m walk p=0.001, d=1.30; 30-second chair stands p=0.035, d=0.70; TUG p=0.084; grip strength p=0.166; Berg Balance p=0.555.
Neutrophil antibacterial function
Neutrophil chemotactic accuracy, E. coli phagocytosis, and PMA-stimulated ROS production improved.
Chemotactic index p=0.003, d=1.1; chemotaxis p=0.044; E. coli phagocytosis p=0.03; ROS production p<0.001, d=1.4.
Monocyte phenotype and function
Total CD16+ monocyte frequency, intermediate monocytes, nonclassical monocytes, and intermediate monocyte TLR2/TLR4/HLA-DR expression decreased; monocyte E. coli phagocytosis increased.
Total CD16+ monocytes p=0.002; intermediate p=0.009; nonclassical p=0.045; TLR2 p=0.005; TLR4 p=0.026; HLA-DR p=0.037; monocyte phagocytosis p=0.02.
Systemic inflammation
No significant changes were observed for IL-1beta, IL-6, CXCL-8, IL-10, CRP, or TNF-alpha.
All reported p values for these markers were >0.05; CRP p=0.322.
Insights
- For selected stable RA patients, high intensity can be delivered as walking intervals with incline rather than running.
- A 30-minute, three-times-weekly HIIT walking program with 60-90 second intervals and similar active recovery is highly reproducible under supervision.
- Claims for clinical populations should preserve the study's control limitation and safety exclusions.
- The intervention suggests a special-population programming pattern: acclimation sessions, HR-based targets, RPE capture, and conservative speed caps.
Limitations
- No healthy control group.
- No RA nonexercise control group.
- Small pilot sample.
- Participants were younger and had lower disease activity than broader RA demographics.
- Supervised structured exercise may not be feasible for broader community or home use.
- Outside physical activity could not be ruled out with certainty.
- Physical activity questionnaires have reliability limitations compared with accelerometry.
- Mechanisms linking exercise, joint improvements, and immune function remain unclear.
Safety
- The program was described as well tolerated.
- No significant adverse events were observed.
- Safety context included supervised sessions, HR targets, acclimation sessions, walking pace speed cap, and exclusion of known cardiovascular disease and diabetes.