Effects of diet and exercise training on neurovascular control during mental stress in obese women

Since neurovascular control is altered in obese subjects, we hypothesized that weight loss by diet (D) or diet plus exercise training (D + ET) would improve neurovascular control during mental stress in obese women. In a study with a dietary reduction of 600 kcal/day with or without exercise training for 4 months, 53 obese women were subdivided in D (N = 22, 33 ± 1 years, BMI 34 ± 1 kg/m²), D + ET (N = 22, 33 ± 1 years, BMI 33 ± 1 kg/m²), and nonadherent (NA, N = 9, 35 ± 2 years, BMI 33 ± 1 kg/m²) groups. Muscle sympathetic nerve activity (MSNA) was measured by microneurography and forearm blood flow by venous occlusion plethysmography. Mental stress was elicited by a 3-min Stroop color word test. Weight loss was similar between D and D + ET groups (87 ± 2 vs 79 ± 2 and 85 ± 2 vs 76 ± 2 kg, respectively, P < 0.05) with a significant reduction in MSNA during mental stress (58 ± 2 vs 50 ± 2, P = 0.0001, and 59 ± 3 vs 50 ± 2 bursts/100 beats, P = 0.0001, respectively), although the magnitude of the response was unchanged. Forearm vascular conductance during mental stress was significantly increased only in D + ET (2.74 ± 0.22 vs 3.52 ± 0.19 units, P = 0.02). Weight loss reduces MSNA during mental stress in obese women. The increase in forearm vascular conductance after weight loss provides convincing evidence for D + ET interventions as a nonpharmacologic therapy of human obesity.

Muscle sympathetic nerve activity and hemodynamic alterations in middle-aged obese women

To study the relationship between the sympathetic nerve activity and hemodynamic alterations in obesity, we simultaneously measured muscle sympathetic nerve activity (MSNA), blood pressure, and forearm blood flow (FBF) in obese and lean individuals. Fifteen normotensive obese women (BMI = 32.5 + or - 0.5 kg/m²) and 11 age-matched normotensive lean women (BMI = 22.7 + or - 1.0 kg/m²) were studied. MSNA was evaluated directly from the peroneal nerve by microneurography, FBF was measured by venous occlusion plethysmography, and blood pressure was measured noninvasively by an autonomic blood pressure cuff. MSNA was significantly increased in obese women when compared with lean control women. Forearm vascular resistance and blood pressure were significantly higher in obese women than in lean women. FBF was significantly lower in obese women. BMI was directly and significantly correlated with MSNA, blood pressure, and forearm vascular resistance levels, but inversely and significantly correlated with FBF levels. Obesity increases sympathetic nerve activity and muscle vascular resistance, and reduces muscle blood flow. These alterations, taken together, may explain the higher blood pressure levels in obese women when compared with lean age-matched women

Eficácia e tolerabilidade das substâncias calorigênicas: ioimbina, triiodotironina, aminofilina combinada a efedrina e feniolpropanolamina no tratamento da obesidade a curto prazo / Efficacy and tolerability of calorigenic substances: yoimbine, triiodothyronine, aminophylline combined with ephedrine and phenylpropanolamine in the short term obesity treatment

Objetivo: Determinar a eficácia e tolerabilidade de 4 substâncias calorigênicas: ioimbina, triiodotironina (T3), combinação efedrina-aminofilina e fenilpropanolamina (FPA). Material, Métodos e Desenho da Pesquisa: 103 mulheres obesas (30 < BMI < 40kg/m 2 ), de 18 a 55 anos, foram submetidas a estudo cego comparativo das 4 substâncias associadas a uma dieta com 1.200 calorias (55 por cento HC, 30 por cento gordura e 15por cento proteínas). As doses utilizadas foram 8mg de ioimbina, 25mcg de T3, 100mg de aminofilina + 25mg de efedrina e 25mg de FPA. Foi ainda incluído um grupo placebo. Os 4 medicamentos e o placebo foram dados 3 vezes ao dia, antes do desjejum, do almoço e do jantar. O estudo se realizou num período de 12 semanas, para cada paciente e no início e o fim do mesmo foram avaliados peso, composição corpórea por bioimpedância, metabolismo de repouso (por calorimetria), pulso e pressão arterial e eventos adversos. Resultados: Houve perda de peso em todos os grupos, mas o único que perdeu peso significativamente em relação ao grupo placebo foi o que recebeu FPA (p < 0,05). Não houve diferença quanto à composição corpórea e metabolismo de repouso entre os 5 grupos. Conclusão: Em nossa amostra, a FPA se revelou mais eficaz, embora este fato não possa ser atribuído a uma maior queima energética em repouso, já que não houve diferença apreciável no metabolismo de repouso entre os grupos.