Weight loss improves neurovascular and muscle metaboreflex control in obesity

Abstract

We studied the effects of a hypocaloric diet (D, n = 24, age: 32.2 +/- 1.4 yr, body mass index: 34.7 +/- 0.5 kg/m2) and a hypocaloric diet associated with exercise training (D + T, n = 25, age: 32.3 +/- 1.3 yr, body mass index: 32.9 +/- 0.4 kg/m2) on muscle metaboreflex control, muscle sympathetic nerve activity (MSNA, microneurography), blood pressure, and forearm blood flow (plethysmography) levels during handgrip exercise at 10% and 30% of maximal voluntary contraction in normotensive obese women. An additional 10 women matched by age and body mass index were studied as a nonadherent group. D or D + T significantly decreased body mass index. D or D + T significantly decreased resting MSNA (bursts/100 heartbeats). The absolute levels of MSNA were significantly lower throughout 10% and 30% exercise after D or D + T, although no change was found in the magnitude of response of MSNA. D + T, but not D, significantly increased resting forearm vascular conductance. D + T significantly increased the magnitude of the response of forearm vascular conductance during 30% exercise. D or D + T significantly increased MSNA levels during posthandgrip circulatory arrest when muscle metaboreflex is isolated. In conclusion, weight loss improves muscle metaboreflex control in obese women. Weight loss reduces MSNA, which seems to be centrally mediated. Weight loss by D + T increases forearm vascular conductance at rest and during exercise in obese individuals.

Sympathetic nervous system behavior in human obesity

“…Weight loss is associated with a reduction in MSNA (Grassi et al, 1998, Trombetta et al, 2003, Straznicky et al, 2005 and whole body NE spillover (Schwartz et al, 1990). Unfortunately, there is currently no information available on whether weight loss lowers SNS activity to the kidney or other tissues/organs.…”

α2B-Adrenergic receptor deletion polymorphism and cardiac autonomic nervous system responses to exercise in obese women

“…This cuff inflated every 30 s, as described previously. 18,19 Body composition determination. Fat body mass and lean body mass parameters were assessed by whole-body dual-energy X-ray absorption anthropometry with HOLOGIC QDR-2000 densitometer.…”

Vitamina C restaura pressão arterial e a resposta vasodilatadora no antebraço em crianças obesas

“…Reduced muscle blood flow and forearm vascular conductance have been well characterized in obese children, adolescents and adults 5,10,18 . Our findings are consistent with these findings in the literature, since we also found that the vascular conductance and blood flow in the forearm muscles are decreased in obese children.…”

“…Obese people present baroreflex dysfunction 4 , increased peripheral vascular resistance 5 , high oxidative stress 6 , as well as increased cardiac and muscular sympathetic activity 7,8 . These changes may lead to increased levels of blood pressure and decreased blood flow to muscles.…”

“…These changes may lead to increased levels of blood pressure and decreased blood flow to muscles. During sympathoexcitatory maneuvers, such as isometric exercise, cold pressor test or mental stress, the vasodilator reflex that should increase muscle blood flow is attenuated in obesity 5,9 . Furthermore, these changes are already present in obese children and it has been shown that non-pharmacological therapy based on diet and exercise can restore the physiological responses of blood pressure and vasodilation during physiological maneuvers of mental stress and isometric exercise 10,11 .…”