# 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 PMID: 29898765 Journal: Arthritis Research & Therapy Published: 2018 Jun 14 Authors: Bartlett DB, Willis LH, Slentz CA, Hoselton A, Kelly L, Huebner JL, Kraus VB, Moss J, Muehlbauer MJ, Spielmann G, Kraus WE, Lord JM, Huffman KM ## 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. ## Population - Sedentary older adults with confirmed stable rheumatoid arthritis. - Sample size: 12 - Age: 64 +/- 7 years. - Sex: 11 women, 1 man. - Fitness level: Sedentary; baseline VO2peak 25.0 +/- 6.6 ml/kg/min. - Health status: Stable, low-to-moderate rheumatoid arthritis; no medication changes for previous 3 months; prednisone <=5 mg/day; known diabetes and cardiovascular disease excluded. ## Methodology - Single-arm supervised pilot intervention with pre/post assessments. - 10 weeks. - Supervised treadmill walking intervention with laboratory clinical, fitness, blood, and immune function assessments. ## Protocol - HIIT walking. - Modality: 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. - Sets or repetitions: Approximately ten high-intensity intervals in the abstract; full text says total intervals adjusted to keep session duration at 30 minutes. - Intensity: Prescribed HR from VO2 reserve; actual high-intensity HR percentage 85 +/- 5%; RPE recorded after each high-intensity bout. - Session duration: 30 minutes including 5-minute warm-up and 5-minute cool-down. - Frequency: 3 sessions per week. - Program length: 10 weeks. - Progression: Three to six acclimation sessions with 30-45 second target-HR intervals and 20-minute total time. ## Outcomes ### VO2peak Status: improved 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 Status: improved 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 Status: improved 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 Status: mixed 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 Status: improved 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 Status: improved 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 Status: no clear change 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. ## Practical 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 And Adherence - 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. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/29898765/) (pubmed) - [DOI](https://doi.org/10.1186/s13075-018-1624-x) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6001166/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.