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Physical Activity Increases Function in Patients With Knee Osteoarthritis

A regular fitness routine was associated with less pain and stiffness, as well as an increase in functional capacity, in patients with knee osteoarthritis.

Physical activity may increase functional capacity and, in conjunction with photobiomodulation (PBM), may increase interleukin-10 (IL-10) levels in patients with knee osteoarthritis (OA), according to a study published in Advances in Rheumatology.1

“For OA, one of the most common treatments is based on pharmacological intervention, mainly nonsteroidal and steroidal anti-inflammatory drugs (NSAIDs). However, the continuous use of NSAIDs can lead to severe adverse effects, like gastrointestinal problems, and limited efficacy,” investigators explained. “In an attempt to attenuate these problems, alternative treatments have been studied including physical exercise programs, presenting positive effects on pain control, joint dysfunction and disability in patients with OA.”

Participants were recruited via social medial and advertisements in this single-blind, randomized controlled trial (RCT) designed to evaluate the impact of physical activity on patients with knee OA. Eligible patients were aged between 55 and 70 years, had symptomatic OA within the previous 6 months, had bilateral or unilateral knee OA, and radiographic confirmation of OA.

Evaluations and reevaluations were performed by blind analysis. Patients were also blinded to the mode of PBM.

The Western Ontario and McMaster Universities Osteoarthritis (WOMAC) assessed functional capacity of knee joints and lower limbs to determine pain, stiffness, and physical activity levels of patients with OA. Blood samples, taken both 48 hours before and 48 hours after intervention, measured levels of CTX-II, IL-1β, IL-10, IL-6, IL-8 e tumor necrosis factor (TNF)-α. Those in the control group continued to maintain their normal habits throughout the 8-week period.

Exercise involved a 5-minute warm-up on the treadmill, a series of 6 strength exercises (seated leg raise, glute bridge, knee flexors, hip abductors and adductors, and extensors chair), as well as a stretching routine. Strengthening exercises consisted of 3 sets of 8 repetitions. Participants were required to perform this protocol 2 times per week for 8 weeks.

Regarding PBM therapy, a cluster dimension of 150 mm(L) x 100 mm(W) x 55 mm(H) with 7 diodes and an infrared wavelength was applied to participants in the EAP cohort after each training session. The equipment was turned off before a researcher applied the sham PMB to the ESP cohort.

Of the 42 patients, 6 were excluded due to missing multiple treatment sessions. At week 8, WOMAC scores were significantly different when compared with baseline scores in both the ESP cohort (p = 0.00006) and EAP cohort (p = 0.00002) as well as between the ESP and CG (p = 0.011). Differences were found between EAP and ESP groups regarding WOMAC pain (p = 0.04) and function ( p = 0.0001) as well as between EAP and CG in the function subscale (p = 0.02) and ESP and CG in pain (p = 0.02) and function (p = 0.01) at week 8.

Further, both ESP and EAP showed significant decreases in all domains by week 8 (p < 0.05). Interestingly, the CG had a significant decrease in WOMAC stiffness.

IL-10 concentration was higher in the EAP group when compared with CG (p < 0.05 and <p < 0.001, respectively).

The small number of patients evaluated and the lack of a follow-up to track maintenance limits the study. Additionally, investigators believe it is important to determine the presence of inflammatory markers in the synovial to solidify the accuracy of the analysis.

“The results of this study demonstrated that the physical exercise program in association with PBM was capable of increasing IL-10 levels, and the physical exercise program improved the function capacity. However, PBM did not promote an additional effect to the positive effects of exercise in improving pro-inflammatory and cartilage degradation biomarkers, and functional capacity in women with knee OA,” investigators concluded. “Thus, more studies need to be carried out, using other parameters, since the literature demonstrates heterogeneity in the parameters of treatment with PBM when associated with physical exercise, for the consolidation of an intervention protocol for patients with knee OA.”


Vassão PG, de Souza ACF, da Silveira Campos RM, Garcia LA, Tucci HT, Renno ACM. Effects of photobiomodulation and a physical exercise program on the expression of inflammatory and cartilage degradation biomarkers and functional capacity in women with knee osteoarthritis: a randomized blinded study. Adv Rheumatol. 2021;61(1):62. Published 2021 Oct 16. doi:10.1186/s42358-021-00220-5