PRESSOR-RESPONSE TO ISOMETRIC-EXERCISE IN PATIENTS WITH MULTIPLE-SCLEROSIS

The purpose of this study was to determine whether patients with multi ple sclerosis (MS) would show attenuated heart rate and/or presser res ponses to isometric handgrip exercise. Patients with MS (30 males, 74 females, aged 23-61 yr) and control subjects (9 males, 16 females, age d 25-47 yr) performed isometric handgrip exercise at 30% of maximal vo luntary contraction (MVC) to fatigue. Systolic, diastolic, and mean ar terial pressure (MAP) increased linearly in both groups, but were sign ificantly lower (P < 0.05) in patients with MS at 20%, 40%, 60%, 80%, and 100% of exercise duration. Mean change in MAP at fatigue was +47.9 mm Hg for controls and +28.2 mm Hg for patients with MS, with 18 pati ents with MS between -6 mm Hg and +15 mm Hg. Heart rate increased norm ally in patients with MS. To predict change in MAP at fatigue in patie nts with MS, stepwise regression analysis using six variables yielded an R(2) of 0.26. These data suggest that in some patients MS lesions e xist in areas of autonomic cardiovascular control that result in atten uated presser responses to exercise. In 17% of patients tested, attenu ation was profound. Data also suggest an abnormal dissociation between the heart rate and presser response to static work in patients with M S.