Fig. 2

Effects of arthritis on voluntary wheel running (experiment 1). a Time course of number of rotations per hour in the dark phase in the saline (blue), CFA (green), and CIA (red) groups. The values are shown as the mean ± standard error of the mean. b Mean number of rotations per hour in the dark phase during the pre-clinical period (days 18–25), early clinical period (days 26–34), and late clinical period (days 35–42). The bars indicate the average number of rotations, and each open circle indicates a value from a mouse. *p < 0.05, **p < 0.01, saline vs. CIA; ^#p < 0.05, ^##p < 0.01, CFA vs. CIA, by one-way ANOVA followed by Tukey’s test. c Time course of arthritis score (right y axis) and number of rotations per hour in the dark phase prior to assessment of arthritis (left y axis). Abscissa, days after first injection. The values are shown as the mean ± standard error of the mean. d₁ Scatter plots showing the relationship between number of rotations in the dark phase prior to assessment of arthritis (y axis) and the arthritis score (x axis) on day 28 (above) and day 38 (below). The insets show the values for Kendall’s tau and the p value for zero correlation d₂ Time course of rank correlation coefficient in the CIA group. The hashed zone indicates the 95% confidence interval for Kendall’s tau. *p < 0.05, **p < 0.01, by Kendall’s correlation analysis. CFA, complete Freund’s adjuvant; CIA, collagen-induced arthritis; n.s., not significant