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Table 1 Rheumatoid arthritis clinical characteristics and disease activity relationships

From: Altered skeletal muscle metabolic pathways, age, systemic inflammation, and low cardiorespiratory fitness associate with improvements in disease activity following high-intensity interval training in persons with rheumatoid arthritis

Variable Cross-sectional RA cohort #1
(n = 47);
Mean (SD)
Cross-sectional RA cohort #1:
associations with
DAS-28;
Spearman’s rho
HIIT RA cohort #2
(n = 12);
Mean (SD)
HIIT RA cohort #2:
associations with improvements in
DAS-28 following HIIT; Spearman’s rho
DAS-28 (mean)
 Baseline 3.0 (1.4)   3.1 (1.5) 0.57
 Post-HIIT    2.3 (1.5)  
ESR (mm/hr) 11.8 (12.0) 0.80*   
 Baseline    10.5 (11.9) 0.64*
 Post-HIIT    7.0 (8.8)  
CRP (mg/L) 6.5 (7.8) 0.47*   
 Baseline    2.7 (3.5) 0.47
 Post-HIIT    2.2 (3.1)  
Swollen joints (n)
 Baseline    4.3 (3.8) 0.74*
 Post-HIIT    1.9 (1.7)  
Tender joints (n)
 Baseline    4.2 (7.0) 0.33
 Post-HIIT    1.9 (2.9)  
Patient global health (mm)
 Baseline    31.5 (15.7) −0.43
 Post-HIIT    22.6 (19.2)  
HAQ-DI 0.67 (0.68) 0.67*   
 Baseline    0.41 (0.34) −0.13
 Post-HIIT    0.35 (0.46)  
Age (years) 54.1 (12.5) 0.05 63.9 (7.2) 0.67*
BMI (kg/m2) 29.9 (6.4) −0.01   
 Baseline    27.4 (9.3) 0.32
 Post-HIIT    27.7 (9.8)  
Gender
 Female 33 (70.2%) 0.07 11 (91.6) 0.10
 Male 14 (29.8%)   1 (8.4%)  
Rheumatoid factor positive 42/47 (89.4%) 0.20 10/12 (83.3%) −0.45
Anti-cyclic citrullinated antibody positive 21/22 (95.6%) −0.21 5/8 (62.5%) −0.29
Erosions on radiographs present 21/38 (55.2%) 0.24 9/12 (75.0%) 0.55
Disease duration (months) 138.9 (136.3) −0.09 159.6 (86.7) 0.18
Body composition
 Abdominal total adipose area (cm2) 408.9 (202.6) 0.05   
 Thigh total adipose area (cm2) 135.7 (66.8) 0.06   
 Thigh muscle area (cm2) 115.8 (37.4) −0.17   
 Thigh muscle density (Hu) 53.4 (8.6) 0.32*   
 Body fat (%)     
 Baseline    36.6 (11.6) 0.53
 Post-HIIT    37.3 (11.2)  
 Lean mass (kg)     
 Baseline    44.9 (8.9) 0.11
 Post-HIIT    44.7 (7.8)  
Sedentary activity (% total daily min) 91.0 (6.0) 0.23   
Total exercise (min/day) 9.7 (14.3) −0.29   
Moderate intensity exercise (min/day) 7.5 (10.5) −0.26   
High intensity exercise (min/day) 1.6 (3.8) 0.36*   
Very high intensity exercise (min/day) 0.5 (2.9) 0.37*   
Baseline cardiorespiratory fitness
(VO2 peak; ml/kg/min)
   24.9 (6.6)
27.1 (7.0)
0.75*
  1. In columns 2 and 4, data are presented as means (SD) for continuous variables and number (percentages) of participants for dichotomous variables. In columns 3 and 5, data are presented as Spearman’s rho
  2. RA rheumatoid arthritis, DAS-28 disease activity score in 28 joints, HIIT high-intensity interval training, ESR erythrocyte sedimentation rate, CRP c-reactive protein, HAQ-DI health assessment questionnaire-disability index, BMI body mass index
  3. *p < 0.05 for Spearman correlations