Should exercise therapy for chronic musculoskeletal conditions focus on the anti-inflammatory effects of exercise?

Exercise therapy for knee osteoarthritis pain: how does it work? A study protocol for a randomised controlled trial

INTRODUCTION

Muscle strengthening training (MST) and behavioural graded activity (BGA) show comparable effects on knee osteoarthritic (KOA) pain, but the mechanisms of action remain unclear. Both exercise-induced anti-inflammation and central sensitisation are promising pathways for pain relief in response to exercise therapy in patients with KOA: MST has the potential to decrease inflammation and BGA has the potential to decrease central sensitisation. Hence, this study aims to examine inflammation and central sensitisation as mediators for the effect of MST and/or BGA on pain in patients with KOA.

METHODS AND ANALYSIS

The Knee OsteoArthritis PAIN trial started on 10 January 2020 (anticipated end: April 2024). The three-arm clinical trial aims to recruit 90 KOA patients who will be randomly allocated to 12 weeks of (1) MST, (2) BGA or (3) care as usual. Assessments will be performed at baseline, 13 and 52 weeks after finishing the intervention. Outcomes, including pain (Knee injury and Osteoarthritis Outcome Score), were chosen in line with the OARSI recommendations for clinical trials of rehabilitation interventions for OA and the IMMPACT/OMERACT recommendations for the assessment of physical function in chronic pain clinical trials. Inflammation as well as features of central sensitisation (including conditioned pain modulation, offset analgesia, temporal summation of pain and event-related potentials following electrical stimulation), will be considered as treatment mediators. A multiple mediators model will be estimated with a path-analysis using structural equation models. In July 2023, all 90 KOA patients have been included and 42 participants already finished the study.

ETHICS AND DISSEMINATION

This study obtained ethics approval (B.U.N. 143201941843). Unravelling the mechanisms of action of exercise therapy in KOA will not only be extremely valuable for researchers, but also for exercise immunology and pain scientists and clinicians.

TRIAL REGISTRATION NUMBER

NCT04362618.

Mechanisms of action of therapeutic exercise for knee and hip OA remain a black box phenomenon: an individual patient data mediation study with the OA Trial Bank

OBJECTIVES

To evaluate mediating factors for the effect of therapeutic exercise on pain and physical function in people with knee/hip osteoarthritis (OA).

METHODS

For Subgrouping and TargetEd Exercise pRogrammes for knee and hip OsteoArthritis (STEER OA), individual participant data (IPD) were sought from all published randomised controlled trials (RCTs) comparing therapeutic exercise to non-exercise controls in people with knee/hip OA. Using the Counterfactual framework, the effect of the exercise intervention and the percentage mediated through each potential mediator (muscle strength, proprioception and range of motion (ROM)) for knee OA and muscle strength for hip OA were determined.

RESULTS

Data from 12 of 31 RCTs of STEER OA (1407 participants) were available. Within the IPD data sets, there were generally statistically significant effects from therapeutic exercise for pain and physical function in comparison to non-exercise controls. Of all potential mediators, only the change in knee extension strength was statistically and significantly associated with the change in pain in knee OA (β -0.03 (95% CI -0.05 to -0.01), 2.3% mediated) and with physical function in knee OA (β -0.02 (95% CI -0.04 to -0.00), 2.0% mediated) and hip OA (β -0.03 (95% CI -0.07 to -0.00), no mediation).

CONCLUSIONS

This first IPD mediation analysis of this scale revealed that in people with knee OA, knee extension strength only mediated ±2% of the effect of therapeutic exercise on pain and physical function. ROM and proprioception did not mediate changes in outcomes, nor did knee extension strength in people with hip OA. As 98% of the effectiveness of therapeutic exercise compared with non-exercise controls remains unexplained, more needs to be done to understand the underlying mechanisms of actions.

Sedentary Behaviour Impairs Skeletal Muscle Repair Modulating the Inflammatory Response

This study investigated whether sedentary behaviour modulates skeletal-muscle repair and tissue inflammatory response after cardiotoxin (CTX)-induced injury. Singly caged rats spent 8 weeks either as a sedentary group (SED, n = 15) or as a control group (EX, n = 15)—caged with running wheels for voluntary running. All rats had each tibial anterior muscle infused either with CTX (CTX; right muscle) or saline solution (Sham; left muscle) and were sacrificed (n = 5 per group) on the 1st, 7th, and 15th day post-injection (dpi). Histological and immunohistochemical analyses were used to calculate myotube percentage and fibrosis accretion, and quantify the number of neutrophils and M1 and M2 macrophage subtypes. The SED group showed an increased number of both neutrophils and M1 macrophages (7th and 15th dpi) compared to the EX group (p < 0.01). The EX group showed an increased number of M2 macrophages on the 1st dpi. On the 7th dpi, the SED group showed a lower myotube percentage compared to the EX group (p < 0.01) and on the 15th dpi showed only 54% of normal undamaged fibres compared to 90% from the EX group (p < 0.01). The SED group showed increased fibrosis on both the 7th and 15th dpi. Our results show that sedentary behaviour affects the inflammatory response, enhancing and prolonging the Th1 phase, and delays and impairs the SMR process.

lncRNA FER1L4 is dysregulated in osteoarthritis and regulates IL-6 expression in human chondrocyte cells

Osteoarthritis (OA) is the most prevalent joint disease and is one of the major causes of disability in the world. There has been an increase in the incidence of OA, which is associated with an aging population, sedentary lifestyle, and reduced physical activity. Due to the complex OA pathogenesis, there are limited diagnostic tools. OA is a degenerative joint disorder with a recognized inflammatory component, usually described as abnormal expression of inflammatory factors. For instance, interleukin 6 (IL‐6) has been shown to be upregulated in serum and synovial fluid among patients with OA. Most of the inflammatory factors have been associated with the expression of long noncoding RNAs (lncRNAs). However, the role of the novel lncRNA Fer-1-like protein 4 (FER1L4) in OA is yet to be determined. Here, we interrogated the expression profile of FER1L4 in patients with OA to define its potential application as a diagnostic marker. We collected synovial fluid and blood samples from both OA cases and normal controls. Using qRT-PCR, we evaluated the expression of FER1L4 in plasma and synovial fluid. On the other hand, the expression of IL-6 in plasma and synovial fluid was assessed using ELISA. Besides, the effect of age, gender or disease stage in the expression of the FER1L4 in plasma was also estimated. Moreover, the receiver operating characteristic (ROC) curves were used to determine the impact of FER1L4 in OA cases compared with the normal controls. In addition, we analyzed the correlation between FER1L4 and IL-6 through Pearson correlation analysis. Also, IL-6 expression in overexpressed FER1L4 samples was detected in chondrocytes through western blot analysis, while FER1L4 expression following endogenous IL-6 exposure was detected by qRT-PCR. Our data showed that whereas lncRNA FER1L4 is downregulated in OA patients, IL‐6 is upregulated. The plasma FER1L4 levels among the OA cases were suppressed with disease progression and old age, and the down-regulation could efficiently discriminate OA patients from normal subjects. In addition, upregulation of FER1L4 inhibited IL‐6 expression in human chondrocyte cells, and treatment with different concentrations of exogenous IL‐6 did not affect the expression of FER1L4. Taken together, our data demonstrates that FER1L4 could efficiently identify OA cases from normal subjects, and can also modulate the expression of IL‐6 in human chondrocytes.

lncRNA HAND2-AS1 is downregulated in osteoarthritis and regulates IL-6 expression in chondrocytes

BACKGROUND

Osteoarthritis (OA) is a leading cause of disability. The incidence of OA is progressively rising due to the diminishing levels of physical activity and ever-expanding aging population. However, the mainstay for OA treatment only can improve symptoms without delay the progression of this severe disease. This study aimed to explore the biological role and clinical function of lncRNA HAND2-AS1 in OA.

METHODS

Blood samples and synovial fluid were collected from OA patients and normal subjects. HAND2-AS1 expression was detected by qRT-PCR and IL-6 expression was detected by ELISA. The plasma levels of HAND2-AS1 were also detected in different ages, stages, and gender of OA patients and controls. Furthermore, the ROC curve was used to analyze whether HAND2-AS1 can distinguish OA patients from normal subjects. Also, Pearson correlation coefficient analysis was used to analyze the correlation between lncRNA HAND2-AS1 and IL-6. In addition, Western blot was used to detect the IL-6 level upon HAND2-AS1 over-expression in chondrocytes and qRT-PCR was used to detect the HAND2-AS1 level after endogenous IL-6 treatment.

RESULTS

HAND2-AS1 and IL-6 were dysregulated in plasma and synovial fluid of OA patients. The expression of HAND2-AS1 in plasma of OA patients was decreased with aging and progression. Furthermore, HAND2-AS1 downregulation effectively distinguished OA patients from the healthy controls. Over-expression of HAND2-AS1 inhibited IL-6 expression in chondrocytes, while treatment with exogenous IL-6 did not affect HAND2-AS1 expression.

CONCLUSION

HAND2-AS1 effectively distinguished OA patients from the healthy controls and regulates IL-6 expression in human chondrocytes.

TRIAL REGISTRATION

ChiCTR, ChiCTR2000038635 . Registered 11 February 2019.

The effect of exercise therapy on inflammatory activity assessed by MRI in knee osteoarthritis: Secondary outcomes from a randomized controlled trial

OBJECTIVE

This study investigated the effect of exercise therapy on inflammatory activity in synovitis and bone marrow lesions (BMLs) assessed by magnetic resonance imaging (MRI) in patients with knee OA.

METHODS

60 patients with knee OA were randomized 1:1 to 12 weeks of supervised exercise therapy 3 times/week (ET) or a no-attention control group (CG). Synovitis and BMLs were assessed with static MRI with and without contrast and with dynamic contrast enhanced MRI (DCE-MRI). DCE-MRI data was quantified using pixel-by-pixel methodology based on analysis of signal intensity curves. Pain was assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS). Analyses of covariance were used assessing group differences in changes from baseline to week 12.

RESULTS

33 patients adhered to the protocol and had valid MRI and KOOS data (ET, n = 16, CG, n = 17). Statistically significant and clinically relevant group difference in favour of ET was seen in KOOS pain change (-11.7 points, 95%CI: -20.1 to -3.4). There were statistically significant group differences in DCE-MRI assessed synovitis in the anterior synovium with unchanged inflammatory activity in the ET group compared to the CG. There were no group differences in BMLs and static MRI.

CONCLUSION

Inflammatory activity was unchanged, and pain was reduced in patients with knee OA adhering to 12 weeks of exercise therapy compared to a no-attention control group. The reduction in pain was not explained by changes in inflammatory activity. Overall, the results suggest that exercise is not harmful in knee OA. ClinicalTrials.gov number: NCT01545258.

Behavioral Graded Activity+ (BGA+) for Osteoarthritis: A Paradigm Shift from Disease-Based Treatment to Personalized Activity Self-Management

Three promising directions for improving care for osteoarthritis (OA) include novel education strategies to target unhelpful illness and treatment beliefs; methods to enhance the efficacy of exercise interventions; and innovative, brain-directed treatments. Here we explain that each of those three promising directions can be combined through a paradigm-shift from disease-based treatments to personalized activity self-management for patients with OA. Behavioral graded activity (BGA) accounts for the current understanding of OA and OA pain and allows a paradigm shift from a disease-based treatment to personalized activity self-management for patients with OA. To account for the implementation barriers of BGA, we propose adding pain neuroscience education to BGA (referred to as BGA⁺). Rather than focusing on the biomedical (and biomechanical) disease characteristics of OA, pain neuroscience education implies teaching people about the underlying biopsychosocial mechanisms of pain. To account for the lack of studies showing that BGA is “safe” with respect to disease activity and the inflammatory nature of OA patients, a trial exploring the effects of BGA⁺ on the markers of inflammation is needed. Such a trial could clear the path for the required paradigm shift in the management of OA (pain) and would allow workforce capacity building that de-emphasizes biomedical management for OA.

Repetitive Knee Bending and Synovitis in Individuals at Risk of and With Knee Osteoarthritis: Data From the Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium

OBJECTIVE

To investigate associations between engagement in knee bending (stair climbing, kneeling, squatting, heavy lifting, getting in/out of a squatting position) and synovitis prevalence on noncontrast magnetic resonance imaging (MRI) in individuals at risk of and with knee osteoarthritis.

METHODS

We included baseline data from 594 participants (mean ± SD age 61.5 ± 8.9 years, 61% had Kellgren/Lawrence grade ≥2; 59% were female; mean ± SD body mass index was 30.7 ± 4.8 kg/m² ) of the Osteoarthritis Biomarker Consortium Foundation for the National Institutes of Health project. Knee bending activities were queried by a standard questionnaire, and the severity of Hoffa synovitis and effusion synovitis (surrogate outcomes of synovitis) were graded using the MRI OsteoArthritis Knee Scoring system. Logistic regression was used, unadjusted and adjusted, for metabolic syndrome, physical activity level, and sex. A grade ≥1 defined synovitis prevalence, with a grade ≥2 cutoff implemented in sensitivity analyses.

RESULTS

The prevalence of grade ≥1 Hoffa synovitis and effusion synovitis equaled 59% (n = 353) and 62% (n = 366), respectively. Adjusted for confounders, kneeling for ≥30 minutes during a single day was associated with grade ≥1 Hoffa synovitis prevalence (odds ratio [OR] 1.65 [95% confidence interval (95% CI) 1.11-2.47]). Participants engaging in this activity ≤1 day per week had greater odds for prevalent Hoffa synovitis than those who did not perform the activity (OR 1.88 [95% CI 1.11-3.18]). No other significant associations were found. Sensitivity analyses yielded similar findings.

CONCLUSION

In this selected sample with a preponderance of grade ≥1 Hoffa and/or effusion synovitis on noncontrast MRI, only prolonged kneeling was associated with Hoffa synovitis prevalence. Replication in other samples is warranted.

Association Between Self-Reported Spinal Morning Stiffness and Radiographic Evidence of Lumbar Disk Degeneration in Participants of the Cohort Hip and Cohort Knee (CHECK) Study

BACKGROUND

Low back pain (LBP) is very common and is a main cause of limited activity and work absence. Patients with LBP may also report spinal morning stiffness; this symptom could be useful for identifying subgroups with signs and symptoms related to spinal osteoarthritis.

OBJECTIVE

This study investigated whether an association exists between reported spinal morning stiffness and radiographic evidence of lumbar disk degeneration (LDD) in people with LBP and a history of pain of the hip and/or knee.

DESIGN

This cross-sectional study used 8-year follow-up data from the Cohort Hip and Cohort Knee study.

METHODS

The association between spinal morning stiffness and radiographic LDD features was assessed with multivariable logistic regression models.

RESULTS

The presence of osteophytes was significantly associated with spinal morning stiffness (odds ratio [OR] = 2.1 [95% confidence interval [CI] = 1.3-3.2]) as was the presence of grade 2 or 3 disk space narrowing (OR = 2.0 [95% CI = 1.1-3.5]). There was also a significant association between morning stiffness persisting for > 30 minutes and grade 2 osteophytes (OR = 2.6 [95% CI = 1.1-6.2]) and grade 1 disk space narrowing (OR = 2.0 [95% CI = 1.1-3.6]). Furthermore, there was a significant association between moderate spinal morning stiffness and the presence of osteophytes (OR = 2.0 [95% CI = 1.2-3.2]). Both the presence of osteophytes and disk space narrowing were significantly associated with severe spinal morning stiffness (for osteophytes: OR = 2.0 [95% CI = 1.2-3.7]; for narrowing at L1-S1: OR = 1.8 [95% CI = 1.1-3.1]).

LIMITATIONS

Only lumbar lateral radiographs were available for each participant, implying that the LDD features could have been underestimated. The quality of the radiographs was not consistent.

CONCLUSIONS

This study showed an association between self-reported spinal morning stiffness and symptomatic LDD. When morning stiffness lasted > 30 minutes, there was a significant association with the features of LDD. The association was stronger when the severity of spinal morning stiffness increased.

Inflammatory cytokines mediate the effects of diet and exercise on pain and function in knee osteoarthritis independent of BMI

OBJECTIVE

Diet restriction and exercise form key treatments for osteoarthritis (OA) related symptoms in overweight and obese individuals. Although both interventions are known to influence systemic low-grade inflammation, which is related to pain levels and functional limitations, little is known about the potential changes in systemic inflammation as a working mechanism of diet restriction and exercise in knee OA.

DESIGN

Data from the Arthritis, Diet, and Activity Promotion Trial (ADAPT) were used. Through causal mediation analyses, the proportion of the effect of a 18 months diet and exercise intervention explained by the 18 months change in interleukin (IL)-6, TNF-α, soluble IL-6 receptor, soluble IL-1 receptor, CRP, and BMI were assessed, using self-reported pain and function as outcomes.

RESULTS

The change in inflammatory factors accounted for 15% of the total effect on pain and was totally independent of the change in BMI. The change in inflammatory factors accounted for 29% of the effect on function, with the change in BMI adding only 4% to the total mediated effect.

CONCLUSIONS

The change in inflammatory factors after the diet and exercise intervention was a 'medium' size mediator of the effect on pain and a 'strong' mediator for the effect on function in overweight and obese individuals with knee OA. The change in BMI added minimally to the mediated effect on function. These results highlight the relevance of changes in systemic inflammation as drivers for clinically relevant effects after diet and exercise in overweight and obese individuals with knee OA.

Physical Activity and Sports-Real Health Benefits: A Review with Insight into the Public Health of Sweden

Positive effects from sports are achieved primarily through physical activity, but secondary effects bring health benefits such as psychosocial and personal development and less alcohol consumption. Negative effects, such as the risk of failure, injuries, eating disorders, and burnout, are also apparent. Because physical activity is increasingly conducted in an organized manner, sport’s role in society has become increasingly important over the years, not only for the individual but also for public health. In this paper, we intend to describe sport’s physiological and psychosocial health benefits, stemming both from physical activity and from sport participation per se. This narrative review summarizes research and presents health-related data from Swedish authorities. It is discussed that our daily lives are becoming less physically active, while organized exercise and training increases. Average energy intake is increasing, creating an energy surplus, and thus, we are seeing an increasing number of people who are overweight, which is a strong contributor to health problems. Physical activity and exercise have significant positive effects in preventing or alleviating mental illness, including depressive symptoms and anxiety- or stress-related disease. In conclusion, sports can be evolving, if personal capacities, social situation, and biological and psychological maturation are taken into account. Evidence suggests a dose–response relationship such that being active, even to a modest level, is superior to being inactive or sedentary. Recommendations for healthy sports are summarized.

Knee extensor strength gains mediate symptom improvement in knee osteoarthritis: secondary analysis of a randomised controlled trial

OBJECTIVE

To determine if an increase in knee extensor strength mediates the effect of a 12-week knee extensor strength training program on pain and physical function improvement in people with knee osteoarthritis (OA).

DESIGN

Secondary analysis from a randomised controlled trial comparing the effects of a 12-week knee extensor strengthening exercise program to a control group with no intervention.

METHODS

Data from participants with complete data (n = 97) enrolled in a previous clinical trial were analysed. Baseline and 12-week follow-up assessments included peak isometric knee extensor strength, pain and physical function. Peak knee extensor strength (Nm/kg) was assessed on an isokinetic dynamometer and subscales of the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index were used to assess pain and physical function. Twelve-week change in pain and physical function were regressed separately, on 12-week change in knee extensor strength and group allocation. Covariates included baseline pain or physical function as appropriate, and baseline knee extensor strength, age, sex and knee alignment (stratification variable).

RESULTS

Improved knee extensor strength mediated the effect of the strengthening program on both pain relief (mediated effect size = 0.69, 95% confidence intervals (CI) 0.05-1.33, P = 0.03), and improved physical function (mediated effect size = 1.86, 95% CI 0.08-3.64, P = 0.04), at 12 weeks.

CONCLUSIONS

Increased knee extensor strength partially mediates the effect of a knee extensor strength training program on pain and physical function improvement in people with knee OA.