Effects of increased muscle perfusion pressure on responses to dynamic leg exercise in man
1988 (English)In: European Journal of Applied Physiology and Occupational Physiology, ISSN 0301-5548, E-ISSN 1432-1025, Vol. 57, no 6, 772-776 p.Article in journal (Refereed) Published
Ventilatory, cardiovascular and metabolic functions and work performance were studied in men performing incremental-load dynamic leg exercise until exhaustion. Part I: Responses to supine exercise were investigated in 8 subjects during exposure of the lower body to subatmospheric pressure at -6.67 kPa (-50 mm Hg) (Lower Body Negative Pressure, LBNP). Due to curtailment of stroke volume, cardiac output was reduced by LBNP over a wide range of work intensities, including heavy loads: ventilation, oxygen uptake and blood lactate concentrations increased with work load, but at lower rates than in the control condition. Part II: In 9 subjects, work performance was compared in three conditions: supine exercise with and without LBNP, and upright exercise. Performance in supine exercise was enhanced by LBNP, and was further improved in upright exercise. In supine exercise, the LBNP-induced reduction in blood lactate and enhancement of work performance are attributed to a more efficient muscle blood flow resulting from increased local perfusion pressure. This strongly suggests that the primary limitation of work performance was set by the peripheral circulation in working muscles rather than by cardiac performance. A similar mechanism may, in part, explain why work performance in dynamic leg exercise was greater in the upright than in the supine posture. It is also concluded that supine leg exercise during LBNP is a useful model of upright exercise, with regard to the central circulation and the circulation in working muscles.
Place, publisher, year, edition, pages
1988. Vol. 57, no 6, 772-776 p.
Work performance, Muscle perfusion pressure, Posture, Muscle blood flow, Lower body negative pressure
IdentifiersURN: urn:nbn:se:kth:diva-44631DOI: 10.1007/BF01076002ISI: A1988P391900019PubMedID: 3416865OAI: oai:DiVA.org:kth-44631DiVA: diva2:452142
QC 201111022011-10-282011-10-252011-11-02Bibliographically approved