Influence of isometric exercise on pressure pain sensitivity in knee osteoarthritis

Isometric exercise is known to have hypoalgesic effects in healthy individuals, but increases pain sensitivity in subjects with chronic pain. Along with improving joint loading, it is unknown whether isometric exercise can decrease pain sensitivity in knee osteoarthritis (OA). The study aimed to assess the influence of isometric exercises (i.e., static quadriceps) on pain sensitivity (i.e., pressure pain threshold; PPT) in knee OA. Methods: This study randomly allocated diagnosed cases of knee OA into two groups (i.e., control and experimental). Participants in the control group were made to sit comfortably for five minutes while in the experimental group performed ten repetitions of isometric quadriceps exercises. Assessment of PPT on the knee joint was performed before and following the intervention for both the groups. Independent t-test was done to compare both the groups after the treatment, and within-group changes were analyzed using paired t-test. Results: Seventy individuals with knee OA participated in the study with thirty six and thirty four subjects in the control and experimental groups respectively. Post-intervention, the mean PPTs were significantly higher in the experimental group (15.3 ± 6.3) compared to the control group (13 ± 5.5) (p < 0.05). No significant differences in PPTs were found within the control group before and after the intervention. Meanwhile, the mean PPTs in the experimental group increased by 23%. Conclusion: The study found that one bout of isometric quadriceps exercise could increase the PPTs when compared to a resting control group in knee OA.