RESUMO
BACKGROUND: The effects of diet and diet plus exercise training on muscle vasodilatation during physiological maneuvers in obese children are unknown. We tested the hypothesis that (1) blood pressure (BP) and forearm vascular conductance (FVC) responses during handgrip exercise and mental stress would be altered in obese children and (2) diet plus exercise training would restore BP and FVC responses during exercise and mental stress in obese children. METHODS AND RESULTS: Thirty-nine obese children (aged 10+/-0.2 years) were randomly divided into 2 groups: diet plus exercise training (n=21; body mass index [BMI]=28+/-0.5 kg/m2) and diet (n=18; BMI=30+/-0.4 kg/m2). Ten age-matched lean control children (BMI=17+/-0.5 kg/m2) were also studied. Forearm blood flow was measured by venous occlusion plethysmography. BP was monitored noninvasively. Handgrip exercise was performed at 30% maximal voluntary contraction for 3 minutes. Stroop color word test was performed for 4 minutes. Baseline BP was significantly higher and FVC was significantly lower in obese children. During exercise and mental stress, BP responses were significantly higher and FVC responses were significantly lower in obese children. Diet and diet plus exercise training significantly reduced body weight. Diet and diet plus exercise training significantly decreased BP levels during exercise and mental stress. Diet plus exercise training, in contrast to diet alone, significantly increased FVC responses during exercise (3.7+/-0.3 versus 5.6+/-0.4 U; P=0.01) and mental stress (3.5+/-0.5 versus 4.5+/-0.4 U; P=0.02). After diet plus exercise training, BP and FVC responses during exercise and mental stress were similar between obese children and the control group. CONCLUSIONS: Obesity exacerbates BP responses and impairs FVC responses during exercise and mental stress in children. Diet and exercise training restore BP and FVC responses in obese children.