The effects of a 12-week structured strength training program on self-reported disease activity in females with rheumatoid arthritis: A series of N-of-1 trials

Abstract

Aim: To investigate the effects of a structured 12-week strength training program on self-reported disease activity and the disease's impact on physical, emotional, and functional domains related to health-related quality of life (HRQoL) in females with rheumatoid arthritis.

Method: Eligibility criteria: Females aged 18-65 with RA and stable disease activity for at least three months were eligible. Outcomes: A numeric rating scale in The Patient Global Assessment (PGA) assessed weekly measurements of self-reported disease activity. The Rheumatoid Arthritis Impact of Disease (RAID) questionnaire was used to weekly assess the patient-important domains (pain, function, fatigue, sleep disturbance, emotional well-being, physical well-being, coping). Muscle strength was measured through isokinetic force production in the knee extensors. The median and interquartile range (IQR) were used to represent the central tendency of PGA and RAID to compare each intervention period. Each of the seven RAID domains was assessed to determine if the results indicated a minimal clinically important improvement (MCII). Intervention: The study followed an N-of-1 experimental design (A1–B–A2) over 20 weeks. During the initial four-week baseline period A1, the participants' baseline values were assessed using the PGA and RAID. Subsequently, it was followed by a 12-week structured strength training period (B) consisting of two weekly training sessions. Each session consisted of three exercises: leg press, chest press, and one-arm seated row. After the strength training period, a four-week wash-out period (A2) commenced.

Results: Participants: A total of six participants completed the intervention, while three withdrew during it. The participants' age and disease duration ranged from 30-50 and 3-35 years, respectively. Four out of six participants at baseline reported low disease activity (PGA), while the remaining two reported substantially higher disease activity scores. Through RAID, three participants reported a low impact of their disease on their HRQoL, one reported a moderate impact, and two reported a high impact. Outcomes: By the end of the intervention, all participants reported low disease activity (PGA) and a low impact of their disease (RAID) on HRQoL, and improvements were considerably higher in those with prominent disease activity at baseline. There were observed MCIIs for pain, physical function, fatigue, and emotional well-being at the end of the wash-out period (A2) in two participants. All participants, except one, showed improvements in their isokinetic force production, ranging from 11% to 29%.

Conclusion: Strength training does not worsen self-reported disease activity and positively affects pain, physical function, fatigue, emotional well-being, and muscle strength in females with RA, with moderate to high disease activity.