People with knee osteoarthritis (KOA) usually present pain sensitization, which impacts the experience of pain and predicts reduced quality of life and low responsiveness to treatments. A graded exercise has been proposed for the treatment of KOA. In this proposal, the practice of physical exercise should be within the individual possibilities, with the potential to remove the fear of exercising and thus create an adequate physical activity routine.

This study aimed to investigate the effects of graded exercise on hyperalgesia in people with KOA compared to an educational control group.

Participants with primary symptoms of pain (≥ 4 on a 0-10 scale) and clinical diagnosis of KOA were recruited. After explanations about the procedures, they signed a consent form and were assessed at baseline and after the intervention. Anthropometric data and pressure pain threshold (PPT) in the center patella at the more symptomatic knee were collected. Three measurements were performed with an algometer (ITO-2020, Japan), with the 30s the intervals between measurements. The mean of them was used for statistical analysis. The participants were randomly assigned to 2 groups for the 14 weeks of intervention: The exercise group and the Education group. The Exercise group performed exercises 3 times a week and had individualized progression of the duration and intensity of the exercise. The session duration initially was of 15-25 minutes and in the end of the intervention of 55 minutes. The participants of exercise group were contacted weekly for evaluation of progress and referral of exercise videos. The educational group also was contacted weekly to clarify doubts. Both groups received educational materials and participated in lectures with health professionals. Two-way ANOVA SPSS (Statistical Package for the Social Science 26.0) was used to compare differences between groups using group-versus-time interaction analysis (significance of 5%).

The study included 27 participants, mostly women (66.7%), mean age of 59,78 years (±9.81) and a mean baseline PPT of 4.2Kgf (±1.40). The two-way ANOVA analysis indicated an increase in the PPT in the Exercise group, compared to the Education group, in the interaction between the group and time factors (P<0.05). The analysis indicated no difference between the groups at baseline (P>0.05).

The graded exercise was effective in reducing hyperalgesia in patients with KOA. Future research about the effects of graded exercise in other pain processing measures and with a larger number of participants must be done to confirm this preliminary conclusion.

Graded exercise is an effective tool for reducing hyperalgesia in people with KOA and can be used to reduce pain sensitization in this population.