Introduction: Rheumatoid arthritis(RA) and osteoarthritis(OA) patients showed systemic manifestations that may lead to a reduction in muscle strength, muscle mass and, consequently, to a reduction in functionality. On the other hand, moderate intensity resistance training(MIRT) and high intensity resistance training(HIRT) are able to improve muscle strength and muscle mass in RA and OA without affecting the disease course. However, due to the articular manifestations caused by these diseases, these patients may present intolerance to MIRT or HIRT. Thus, the low intensity resistance training combined with blood flow restriction(LIRTBFR) may be a new training strategy for these populations. Objective: To perform a systematic review with meta-analysis to verify the effects of LIRTBFR on muscle strength, muscle mass and functionality in RA and OA patients. Materials and methods: A systematic review with meta-analysis of randomized clinical trials(RCTs), published in English, between 1957–2021, was conducted using MEDLINE(PubMed), Embase and Cochrane Library. The methodological quality was assessed using Physiotherapy Evidence Database scale. The risk of bias was assessed using RoB2.0. Mean difference(MD) or standardized mean difference(SMD) and 95% confidence intervals(CI) were pooled using a random-effects model. A P<0.05 was considered statistically significant. Results: Five RCTs were included. We found no significant differences in the effects between LIRTBFR, MIRT and HIRT on muscle strength, which was assessed by tests of quadriceps strength(SMD = -0.01[-0.57, 0.54], P = 0.96; I² = 58%) and functionality measured by tests with patterns similar to walking(SMD = -0.04[-0.39, 0.31], P = 0.82; I² = 0%). Compared to HIRT, muscle mass gain after LIRTBFR was reported to be similar. When comparing LIRTBFR with low intensity resistance training without blood flow restriction(LIRT), the effect LIRTBFR was reported to be higher on muscle strength, which was evaluated by the knee extension test. Conclusion: LIRTBFR appears to be a promising strategy for gains in muscle strength, muscle mass and functionality in a predominant sample of RA and OA women.

Metabolomic analysis provides a wealth of information that can be predictive of distinctive phenotypes of pathogenic processes and has been applied to better understand disease development. Rheumatoid arthritis (RA) is an autoimmune disease with the establishment of chronic synovial inflammation that affects joints and peripheral tissues such as skeletal muscle and bone. There is a lack of useful disease biomarkers to track disease activity, drug response and follow-up in RA. In this review, we describe potential metabolic biomarkers that might be helpful in the study of RA pathogenesis, drug response and risk of comorbidities. TMAO (choline and trimethylamine oxide) and TCA (tricarboxylic acid) cycle products have been suggested to modulate metabolic profiles during the early stages of RA and are present systemically, which is a relevant characteristic for biomarkers. Moreover, the analysis of lipids such as cholesterol, FFAs and PUFAs may provide important information before disease onset to predict disease activity and treatment response. Regarding therapeutics, TNF inhibitors may increase the levels of tryptophan, valine, lysine, creatinine and alanine, whereas JAK/STAT inhibitors may modulate exclusively fatty acids. These observations indicate that different disease modifying antirheumatic drugs have specific metabolic profiles and can reveal differences between responders and non-responders. In terms of comorbidities, physical impairment represented by higher fatigue scores and muscle wasting has been associated with an increase in urea cycle, FFAs, tocopherols and BCAAs. In conclusion, synovial fluid, blood and urine samples from RA patients seem to provide critical information about the metabolic profile related to drug response, disease activity and comorbidities.

Introduction: Self-reported disability is potentially influenced by many factors in patients with rheumatoid arthritis (RA). In this sense, we evaluated the association between self-reported disability and (1) clinical features, (2) muscle strength and (3) physical performance over time among patients with RA from two distinct patient cohorts.Materials and methods: Two independent prospective RA cohorts were analyzed. The Health Assessment Questionnaire (HAQ), Disease Activity Score in 28 Joints (DAS28), handgrip test, chair stand test, timed-up-and-go (TUG) test and Short Physical Performance Battery (SPPB) were performed at baseline and in follow-up. T test for independent samples, Mann-Whitney U test, Spearman correlation coefficients and linear regression with generalized estimating equations were performed to assess associations between individual constructs at baseline and over time.Results: A total of 205 total RA patients were included [North American Cohort (n = 115); Brazilian Cohort (n = 90)]. At enrollment, Brazilian men had better HAQ than North American men (p<0.001). Brazilian patients overall had lower muscle strength than North American patients (p<0.05). HAQ was associated with DAS28, handgrip test, chair stand test, TUG and SPPB (p<0.001) in both cohorts. Worsening of the DAS28 and chair stand test were each associated with worsening in HAQ in longitudinal analysis over time. Worsening of handgrip was also associated in with worsening HAQ in both cohorts (p<0.05). A worse TUG test was associated with worsening in HAQ in Brazilian cohort (p<0.05) and a worse SPPB was associated with worsening in HAQ in North American cohort (p<0.05).Conclusion: Greater disability measured by HAQ is closely associated with disease activity, pain, muscle strength, and physical performance among RA. Worsening in self-reported disability correlate with worsening clinical factors including objectively-observed physical function.

Background: Rheumatoid arthritis (RA) is an autoimmune, inflammatory and chronic disease that may lead to loss of muscle mass, muscle strength and decreased functionality. Our objectives are to assess the quadriceps muscle morphology by ultrasound (MU) and verify its associations with clinical features, muscle strength and physical function in RA patients. Methods: In this cross-sectional study, RA women (≥18 years) were included. Morphological parameters in quadriceps muscle consisted of the muscle thickness and pennation angle of rectus femoris (RF), vastus intermedius (VI) and vastus lateralis (VL). RA activity was measured by a 28-joint disease activity score (DAS28), muscle strength by handgrip and chair stand tests, and physical function by health assessment questionnaire (HAQ), timed-up-and-go (TUG) test and short physical performance battery (SPPB). Results: Fifty-five patients were included (age: 56.73 ± 9.46 years; DAS28: 3.08 ± 1.29). Muscle thickness in RF, VI and VL were negatively associated with age (RF, p < 0.001; VI, p = 0.013; VL, p = 0.002) and disease duration (RF, p < 0.001; VI, p = 0.005; VL, p = 0.001), and were positively associated with handgrip strength (RF, p = 0.015; VI, p = 0.022; VL, p = 0.013). In addition, decreased muscle thickness in VI (p = 0.035) and a smaller pennation angle in RF (p = 0.030) were associated with higher DAS-28 scores. Conclusion: Quadriceps muscle morphology by ultrasound appears to be affected by age, disease duration, disease activity and muscle strength in patients with RA. MU can be a useful method to evaluate the impact of the disease on skeletal muscle.