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Abstract Peripheral arterial occlusive disease ( PAOD ) is the most common peripheral disease in the elderly [Hooi et a! ., 1999] . Patients with PAOD often complain of intermittent claudication . This causes great limitation of life because of reduction in walking ability [ Remijnse et a! ., 1999 ] . Such patients have low basal muscular perfusion and during exercise , blood flow to the exercising muscle mass is unable to meet the requirements of the increased metabolic activity. Accumulation of metabolites explains the early appearance of peripheral fatigue phenomenon in peripheral arterial disease (PAD ) patients [Kempczinski et a! ., 2000] . Such patients are commonly classified on the basis of subjective evaluations of pain and fatigue [ Casale eta!., 1994]. It could be important to have , at least , an objective evaluation of fatigue Such objective measurement of fatigue may allow better evaluation of the intermittent claudication which is the most important symptom in PAD patients . In addition , assessment of muscle fatigue has been proposed to evaluate load limits both during rehabilitation training and in the working environment [Hagberg et al ., 1992 ] . Electromyography ( EMG ) is an objective method which has been widely used in studying peripheral muscle fatigue [ Karger et al ., 1983 ] . Spectral compression of the electromyographic signal is one of the most recent parameters used as muscle fatigue indicators . Changes in the characteristic frequencies of the power spectrum such as the mean power frequency ( MPF ) and the median frequency ( MDF ) are the current methods denoting spectral compression [ Lowery eta! ., 2000] . Median frequency ( MDF ) is defined as the frequency value which divides the power density into two sections of equal energy content [ De luca et a! ., 1984 ] . Because of its greater precision as compared to other spectral parameters , MDF is used to monitor EMG spectral shift toward lower frequencies due to muscle fatigue [ Merletti et a! ., 1998 ] . Vascular rehabilitation for PAOD patients is suggested by many authors to be effective in relieving pain, improving function and promoting optimal wellness [Spitzer et a! ., 1992 , Alexander et a! ., 1993 , Regensteiner et a! ., 1996 , Pedrinelli eta! ., 1998 and Tan et a! ., 2000 ] . For serial quantitative assessment of different vascular rehabilitation programs designed for claudicants , it could be important to have an easy , painless , repeatable method which gives objective information on muscular performance and fatigue in PAD patients . Before routinely using median frequency of the myoelectric signal for detecting the changes in the muscular performance owing to a rehabilitation program or any other intervention modality for the management of PAOD patients, spectral frequency parameters response to physical training and I or any other interference in such patients should be studied and compared with a well documented prognostic marker for the PAOD such as ankle I brachial pressure index of the Doppler ultrasound blood flow detection . |