Background Fatigue is an important clinical manifestation reported by patients with Rheumatoid Arthritis (RA). The assessment of fatigue in RA is usually conducted using subjective questionnaires, including emotional and socials aspects1. However, little is known on peripheral fatigue (muscle fatigue) for patients with RA, which can be assessed by surface electromyography (sEMG)2.
Objectives To assess the relationship between perception of fatigue and peripheral fatigue in patients with RA. In addition, the relationship between these two parameters of fatigue with clinical disease features from these patients was evaluated.
Methods Thirty eight female patients with RA were included. Peripheral fatigue [by assessing changes in magnitude, root mean square (RMS) and frequency, median frequency (MDF) of the muscle activation during a 60-s quadriceps test] and perception of fatigue (FACIT-F) were assessed. In addition, demographic data [age and disease duration, calculated by elapsed time from diagnostic], hemoglobin (Hb-g/dL), DAS-28, HAQ and International Physical Activity Questionnaire (IPAQ, long version) were measured. Significance was considered p≤0.05.
Results RA patients had an average age and disease duration of 51.0±8.22 and 12.18±6.99 years old. Patients had mean hemoglobin, DAS-28, HAQ and IPAQ of 13.04±1.05 g/dL, 2.99±1.06, 0.73±0.6 and 229.95±237.97 (min/week), respectively. In perception of fatigue, we found a mean FACIT-F, - FACIT-TOI (the sum of the physical well-being, functional well-being and “additional concerns”) and FACIT- TOTAL SCORE of 14.68±7.23, 39.42±10.81 and 65.53±17.24, respectively. For eletromiographic variables, an increase in magnitude of activation (RMS) and a decrease in frequency of muscle activation (MDF) was observed during the 60s test. The association between perception of fatigue and sEMG findings, and clinical disease features are presented in table I.
Conclusions This study confirms that patients with RA showed increase perception of fatigue and peripheral fatigue (muscle fatigue). However, there was no correlation between perception of fatigue and peripheral fatigue, as measured by sEMG, which indicates that patients with RA may underscore their muscle performance possibly due to joint pain. Additionally, the correlation between MDF with age and physical activity level in our patients, indicates that better muscle endurance (lower decline in MDF during the 60s test) are observed in patients that practice physical activity more often. Then it could be speculated that regular physical activity could lead to the maintenance of muscle performance in RA patients and change the perception of fatigue in RA patients.
Hewlett S, Chalder T, Choy E, Cramp F, Davis B, Dures E et al. Rheumatology (Oxford).2011;50(6):1004-6.
Arjunan SP,Kumar DK, Naik G. Biomed Rest Int.2014;2014.
Disclosure of Interest None declared