Muscle metaboreflex control is diminished in normotensive obese women

There is no information about the muscle metaboreflex control in obese indi viduals. In 40 normotensive obese women (OW; body mass index 33.5 +/- 0.4 k g/m(2), age 32.4 +/- 1.1 yr) and 15 age-matched, normotensive lean women (L W; body mass index 22.7 +/- 0.8 kg/m(2), age 34.4 +/- 1.4 yr), we measured muscle sympathetic nerve activity (MSNA) and forearm blood flow (FBF) in th e nonexercising forearm during static exercise at 10 and 30% of maximal vol untary contraction (MVC). Baseline MSNA (38 +/- 2 vs. 31 +/- 1 bursts/min, P = 0.001) and mean blood pressure were significantly higher in OW compared with LW. FBF was significantly lower, whereas forearm vascular resistance was significantly higher in OW. During 10% MVC, MSNA increased similarly in both groups, but during 30% MVC, MSNA was higher in LW. FBF and forearm va scular resistance responses during both 10 and 30% MVC were similar between groups. During post-handgrip circulatory arrest, MSNA remained significant ly elevated compared with baseline in both groups, but this increase was si gnificantly lower in OW (3.8 +/- 0.82 vs. 9.4 +/- 1.03 bursts/min, P = 0.00 2). In conclusion, muscle metaboreflex control of MSNA is blunted in OW. MS NA responses are not augmented during selective activation of central comma nd/mechanoreceptors and metaboreceptors, despite increased MSNA levels in O W. Muscle vasodilatory response during graded handgrip isometric exercise i s preserved in OW.