Exercise-improved walking capacity in patients with peripheral arterial disease: Effects and mechanisms
Wang, JX, Zhou, S, Marshall-Gradisnik, SM, Bronks, R, Graham, J & Myers, SP 2004, 'Exercise-improved walking capacity in patients with peripheral arterial disease: Effects and mechanisms', paper presented to 3rd Annual Conference of the Society of Chinese Scholars on Exercise Physiology and Fitness: The Professional Development of Exercise Physiology and Fitness in the New Century, Su Zhou, China, 29 October - 1 November.
Peripheral arterial disease (PAD) is an atherosclerotic disease. The most common symptom of PAD is intermittent claudication, a severe muscular pain in the lower limbs when walking. This symptom seriously deteriorates walking capacity and quality of life of PAD patients. It has been reported that exercise training can effectively enhance walking capacity in PAD patients. However, the mechanisms underlying the improved walking capacity have not been fully understood. The purpose of this study was to investigate some of the possible mechanisms using multi-disciplinary approaches. It has also been reported that an herbal medicine, ginkgo biloba extract, can improve peripheral circulation. A secondary purpose of the study was to examine the effects of ginkgo treatment on PAD.
Seventeen PAD patients with an average age of (mean±SD) 71.4±7.1 years, resting ankle-to-brachial index of less than 0.61 and at least six months’ history of intermittent claudication, were recruited and randomly assigned into the ginkgo or placebo group. The patients were firstly given a 12-week ginkgo biloba extract (240mg/day) or placebo treatment, followed by 12 weeks of supervised exercise training in combination with ginkgo biloba or placebo treatment. The patients trained in three one-hour sessions per week on treadmill with the intensity determined by the level of claudication pain. Treadmill walking capacity, peak oxygen uptake, walking economy, calf muscle strength and endurance, erythrocyte characteristics, blood lipid profile, muscle capillary supply and activities of phosphofructokinase and citrate synthase were evaluated at the baseline and at pre and post training. Repeated measures ANOVA was performed to evaluate the treatment effects.
There were no significant changes in the measured variables in response to the ginkgo biloba treatment, therefore the results of the two groups were collapsed in statistical analysis for the effects of exercise training. The walking capacity, peak oxygen uptake, calf muscle strength and endurance were significantly increased and walking economy was significantly improved after the 12-week supervised exercise training. Significant correlations were found between the increased walking capacity and improved walking economy, calf muscle endurance and capillary supply to type II muscle fibres.
The results indicated that the improved walking capacity was unlikely due to improved peripheral hemodynamics as measured by ABI, rheologic characteristics and the muscle enzyme activities, while the status of walking economy, calf muscle endurance, and capillary supply to type II muscle fibres appeared to be important factors affecting the walking capacity of PAD patients after the treadmill training.