The reliability of isometric strength and fatigue measures in patients with knee osteoarthritis

Christopher J. McCarthy, Michael J. Callaghan and Jacqueline A. Oldham

This study used the closed kinetic chain approach to muscle assessment in patients with knee osteoarthritis. Maximum voluntary isometric contraction into extension was assessed in 55 subjects by isokinetic dynamometer with a closed kinetic chain “leg press” attachment. Muscle fatigue was assessed by EMG assessment of signal median frequency during a 60 s isometric contraction at 60% of maximum isometric contraction. Results showed the reliability of the maximum voluntary isometric contraction extension strength test however, the fatigue slopes for all three muscles were unreliable.

While the use of a closed kinetic chain leg press technique provides a reliable measurement of lower limb strength, EMG power spectrum decrease during an isometric contraction is of little value.

Manual Therapy, 2008, 13(2), 159-164

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