Isokinetic and isometric muscle strength of the knee flexors and extensors in patients with the Fibromyalgia syndrome and chronic Myofascial pain syndrome

Objectives: To compare Muscular performance of the patients with the fibromyalgia syndrome [FMS] and chronic myofascial pain syndrome [MPS] with each other and with healthy normal controls [HNCs]. Methods: Maximum voluntary isokinetic and isometric muscle strength of the knee extensors and flexors in the dominant limb was measured using an isokinetic dynamometer in 18 patients with FMS. 16 patients with NIPS, and 36 HNCs. The participants performed five repetitions of flexion and extension at 60 degrees per second [degrees/s] and 180 degrees/s for isokinetic measurements. Isometric performance was measured at 30 degrees/s and 60 degrees/s. Results: Gender [all were female], age, physical activity levels, body mass index of the three groups. and disease duration of the two patient 0 groups were similar. Peak torques and total work in both flexion and extension were lower in both patient groups compared to HNCs. Mean peak torque of the knee flexors was lower in FMS than in NIPS. Total work did not differ between FMS and NIPS. Flexor and extensor endurance ratio in the FMS and MPS groups were not different from each other and from that of HNCs. Isometric strength of the knee flexors and extensors were lower in both patient groups than in HNCs. Isometric strength of knee flexors at 30/s was lower in FMS compared to MPS. Conclusion: Muscular performance both of FMS and NIPS patient groups was low compared to HNCs. The FMS patients showed lower isokinetic flexion and isometric extension strength than the MPS patients at some particular speeds.