Padrões de fluxo sanguíneo no membro inferior durante o exercício em cicloergômetro de braço em participantes com doença arterial periférica

Abstract

INTRODUCTION: Peripheral Arterial Disease (PAD) is a chronic condition characterized by arterial obstructions, usually caused by atherosclerosis, which reduce blood flow to peripheral tissues, leading to symptoms such as intermittent claudication and impairing quality of life and physical activity capacity. Arm-crank ergometer (AE) exercise has emerged as a less painful aerobic alternative for individuals with PAD, promoting functional gains possibly due to increased blood flow to the lower limbs. This increase may stimulate nitric oxide production, enhancing vasodilation, reducing peripheral vascular resistance, and improving muscle perfusion. Shear stress, resulting from the interaction between blood flow and arterial walls, plays a key role in this process, influencing vascular function and the progression of atherosclerosis. However, the mechanisms by which AE affects shear stress in the lower limbs remain unclear. OBJECTIVE: To evaluate shear stress and blood flow parameters in lower limb arteries during AE exercise in participants with PAD. METHODS: This is a crossover study with 10 participants with PAD and symptoms of intermittent claudication. Participants underwent three randomized experimental sessions: AE, foot immersion in warm water, and control. During AE, 15 sets of 2 minutes were performed at an intensity of 13–15 on the Borg Scale, with 2-minute passive intervals. During foot immersion, 15 sets of 2 minutes at 42°C were alternated with intervals without immersion. In the control session, participants remained seated for 60 minutes. Femoral artery diameter and blood flow were monitored by Doppler ultrasonography to calculate shear stress, and blood pressure and heart rate were measured every 6 minutes. Statistical analyses were performed using STATISTICA with p<0.05. RESULTS: Arterial diameter was greater during the AE (0.36±0.08cm vs 0.30±0.12cm; p<0.001) and foot immersion (0.36±0.14cm vs 0.30±0.12cm; p=0.010) sessions compared to the control session. Blood flow was higher during the AE (751.6±218.4mL/min vs 565.0±108.7mL/min; p<0.001) and foot immersion (754.4±243.0mL/min vs 565.0±108.7mL/min; p<0.001) sessions compared to the control. The antegrade shear rate was higher during the AE (190.7±18.9s⁻¹ vs 152.3±15.5s⁻¹; p<0.001) and foot immersion (194.3±18.6s⁻¹ vs 152.3±15.5s⁻¹; p<0.001) sessions compared to the control. CONCLUSION: AE exercise increases blood flow, antegrade shear rate, and arterial diameter in the femoral artery of individuals with PAD, indicating that upper limb ergometers provide a beneficial vascular stimulus to the lower limbs.