Accession Number : ADA133928

Title :   Experiments on Factors That Influence Muscular Function in Man.

Descriptive Note : Final rept. Jul 80-Sep 82,


Personal Author(s) : Lind,A R ; Williams,C A ; Hoffman,M D

Full Text :

Report Date : 25 May 1983

Pagination or Media Count : 79

Abstract : Research was concerned with muscular function and fatigue. The systemic cardiovascular responses are much the same when the contractions result in muscular fatigue, at which time the mean blood pressure is the same as it is in response to sustained isometric contractions. All the available evidence points to the same mechanisms being involved, centering around the reflex of chemical origin in active muscles. There appears, however, to be considerable differences in the local control of blood vessels when isometric contractions are pursued to fatigue on a continuous or on an intermittent basis. In the present experiments we have shown that the constriction is neural in origin and that metabolites which normally inhibit that constriction are unable to migrate through the interstitial space to larger arterioles not in the direct vicinity of the contracting muscles. The performance of very short bouts of rhythmic exercise can result in dramatic reductions of isometric endurance and, to some extent, isometric strength. The functional consequences are obvious: jobs calling for either isometric strength or endurance can be seriously impaired by previous rhythmic exercise. The causes are only partially disclosed by our experiments.

Descriptors :   *Muscles , *Exercise(Physiology) , Heart rate , Physiological effects , Human body , Blood circulation , Control , Fatigue(Physiology) , Blood pressure , Contraction , Functions , Metabolites , Endurance(Physiology)

Subject Categories : Anatomy and Physiology
      Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE