Blunted pressor and intramuscular metabolic responses to voluntary isometric exercise in multiple sclerosis. J Appl Physiol (1985) 2000 Mar;88(3):871-80
Date
03/10/2000Pubmed ID
10710381DOI
10.1152/jappl.2000.88.3.871Scopus ID
2-s2.0-0034013788 (requires institutional sign-in at Scopus site) 36 CitationsAbstract
To test the hypothesis that a lower mean arterial pressure (MAP) response during voluntary isometric exercise in multiple sclerosis (MS) is related to a dampened muscle metabolic signal, 9 MS and 11 control subjects performed an isometric dorsiflexor contraction at 30% maximal voluntary contraction until target failure (endurance time). We made continuous and noninvasive measurements of heart rate and MAP (Finapres) and of intramuscular pH and P(i) (phosphorus magnetic resonance spectroscopy) in a subset of 6 MS and 10 control subjects. Endurance times and change in heart rate were similar in MS and control subjects. The decrease in pH and increase in P(i) were less throughout exercise in MS compared with control subjects, as was the change in MAP response. Differences in muscle strength accounted for some of the difference in MAP response between groups. Cardiovascular responses during Valsalva and cold pressor tests were similar in MS and control subjects, suggesting that the blunted MAP response during exercise in MS was not due to a generalized dysautonomia. The dampened metabolic response in MS subjects was not explained by inadequate central muscle activation. These data suggest that the blunted pressor response to exercise in MS subjects may be largely appropriate to a blunted muscle metabolic response and differences in contracting muscle mass.
Author List
Ng AV, Dao HT, Miller RG, Gelinas DF, Kent-Braun JAAuthor
Alexander V. Ng PhD Associate Professor in the Exercise Science department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
AdultAutonomic Nervous System
Blood Pressure
Case-Control Studies
Cold Temperature
Electromyography
Female
Heart Rate
Humans
Hydrogen-Ion Concentration
Isometric Contraction
Male
Middle Aged
Multiple Sclerosis
Muscle Fatigue
Muscle, Skeletal
Phosphates
Phosphocreatine
Valsalva Maneuver
