The objective of this brief review is to discuss current hypotheses describing the roles of the arterial baroreflex and reflexes originating from afferents within the active skeletal muscle (metaboreceptors and mechanoreceptors) in mediating reflex changes in heart rate. The major focus is on how the techniques of reflex activation and analysis of the subsequent responses may markedly affect conclusions drawn regarding the role of these reflexes during exercise. The disparate conclusions regarding the importance of these reflexes are likely reflective of the different autonomic mechanisms mediating the reflex responses (i.e., parasympathetic vs sympathetic) as well as the techniques utilized for reflex activation and analysis. Conclusions reached are that these reflexes are important in the regulation of heart rate during exercise but the relative roles are dependent on work load.
Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201
Submitted for publication October 1994.
Accepted for publication October 1995.
The author would like to thank Drs. Loring B. Rowell and Don D. Sheriff for the many opportunities for consultation and collaboration. The author's research was supported by National Heart Lung and Blood Institute Grants HL-45038 and HL-02844.
Address for correspondence: Donal S. O'Leary, Ph.D., Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201; E-mail: firstname.lastname@example.org.