Effects of quadriceps isometric contraction training on symptoms, postural control, and movement ability in older women with knee osteoarthritis

Objective This study investigates the effects of quadriceps isometric contraction training (QICT) on the symptoms, postural control, and movement ability of elderly women with knee osteoarthritis (KOA). Methods Forty-two older women with KOA were randomly divided into an experimental group (n = 21) and a control group (n = 21). All participants received the same health education for 16 weeks. The experimental group underwent QICT five times per week (contraction and relaxation for 5 s each, 30 repetitions per set, 10 sets, with a 30-s rest between sets). Assessments of KOA symptoms, postural control, and movement ability were performed at baseline and after the 16-week intervention. Results 1) At the 16th week compared to baseline: The experimental group showed a 27.1% reduction in pain, a 13.8% reduction in stiffness, and a 15.7% reduction in functional impairment scores. The body sway index on a firm surface with eyes closed decreased by 14.3%. The knee extension peak torque at 180°/s increased by 31.6%, and the angle difference in the knee flexion proprioception test (30°) decreased by 24.5%. The 6MWT distance increased by 11.9%, and the time for the TUG decreased by 12.9% (P < 0.05). 2) At the 16th week, group comparisons showed that the experimental group had significantly lower pain scores, body sway index on a firm surface with eyes closed, and angle difference in the knee flexion proprioception test (30°) (P < 0.05), and significantly higher knee extension peak torque at 180°/s and 6MWT distance compared to the control group (P < 0.05). Conclusion Quadriceps isometric contraction training can significantly improve pain, stiffness, functional impairment, static balance ability, knee extension strength, and 6-min walk distance in older women with KOA, as well as enhance knee flexion proprioception. These results indicate that 16-week QICT is a safe and economical non-pharmacological intervention that can effectively improve the clinical symptoms and functional status of older women with KOA, providing a feasible treatment option for community and outpatient rehabilitation. Notably, the 31.6% increase in knee extensor peak torque (180°/s) exceeds the MCID (20%) for older adults with KOA, reflecting significant clinical benefits.