The present study examined whether daily physical activity moderated the within-person relationship between daily fatigue and positive or negative mood in patients with rheumatoid arthritis (RA) or osteoarthritis (OA).
Participants were 142 patients, 70 with RA and 72 with OA (67.6% women). Participants completed daily diaries during 4 fixed time windows per day for 7 days. Each diary assessed fatigue, pain, and positive and negative mood. Participants wore pedometers throughout each day and recorded pedometer readings at the end of each day.
Physical activity buffered the same-day relationship between daily fatigue and positive mood for both RA and OA participants. On high-fatigue days, large decrements in mood were noted, but this was mitigated on days when participants were more physically active.
Being more physically active on high-fatigue days buffered the negative effect of fatigue on positive mood among adults with both OA and RA. These findings have implications for understanding the daily variations in fatigue and inform potential clinical interventions.