In individuals with knee osteoarthritis (OA) who are ineligible for knee replacement surgery, the addition of strength training to neuromuscular exercise and education decreases pain sensitization and intensity compared with neuromuscular exercise and education alone, according to study results published in European Journal ofPain.
There is a lack of evidence on the relative effects of different exercise modalities on pain intensity and sensitization in individuals with knee OA. Therefore, the investigators of the current study sought to evaluate the effects of strength training plus neuromuscular exercise and education vs neuromuscular exercise and education alone on measures of pain in individuals with knee OA.
A randomized secondary analysis (EXTRA study; ClinicalTrials.gov Identifier: NCT03215602) from the patient-blinded, parallel-group, randomized controlled trial was conducted in Denmark. Individuals with radiographic and symptomatic knee OA who were not eligible for knee replacement surgery were randomly assigned for 12 weeks between July 2017 and October 2018 to either twice-weekly strength training plus neuromuscular exercise and education (ST+NEMEX-EDU) or neuromuscular exercise and education alone (NEMEX-EDU).
Study outcomes included bilateral, lower-leg, cuff pressure pain threshold (PPT), pain tolerance threshold (PTT), temporal summation (TS), conditioned pain modulation (CPM), number of painful body sites, and self-reported knee pain intensity.
A total of 90 individuals with knee OA were included in the analysis. Significant differences were observed after 12 weeks of exercise in increases in PPT (-5.01 kPa; 95% CI, -8.29 to -1.73 kPa; P =.0028) and PTT (-8.02 kPa; 95% CI, -12.22 to -3.82 kPa; P =.0002) in the leg with knee OA, favoring ST+NEMEX-EDU. No statistically significant differences were seen in effects between the ST+NEMEX-EDU group and the NEMEX-EDU group on TS, CPM, or number of painful body sites.
Investigators reported a statistically significant difference between the groups in visual analog scale (VAS) knee pain at week 12, with a larger pain reduction in the NEMEX-EDU group (adjusted mean difference, -8.4 mm; 95% CI, -16.2 to -0.5 mm; P =.0364). Further, a significant difference was also observed between the groups in VAS pain after 30 minutes of walking at week 12, with a larger pain reduction in the NEMEX-EDU group (adjusted mean difference, -16.0 mm; 95% CI, -24.8 to -7.3 mm; P =.0004). No statistically significant differences between the groups were observed in knee pain intensity during the previous 24 hours or in the number of painful body sites at 6 or 12 weeks.
A major limitation of the current analysis was the fact that the study sample was powered for the primary randomized controlled study, suggesting that the results should be interpreted with caution.
Investigators concluded, “The study provides the first dose- and type-specific insight into the effects of a sustained exercise period on pain sensitization in [knee] OA. Future studies are needed to elucidate the role of different exercise modes.”
Holm PM, Petersen KK, Wernbom M, Schrøder HM, Arendt-Nielsen L, Skou ST. Strength training in addition to neuromuscular exercise and education in individuals with knee osteoarthritis. Eur J Pain. Published online May 15, 2021. doi:10.1002/ejp.1796