| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 School of Physical and Health Education and Department of Physiology, Queen's University, Kingston, Ontario, Canada
* To whom correspondence should be addressed. E-mail: mt29{at}post.queensu.ca.
Controversy exists regarding the contribution of a rapid vasodilatory mechanism(s) to immediate exercise hyperemia. Previous in vivo investigations have exclusively examined rest-to-exercise (R-E) transitions where both the muscle pump and early vasodilator mechanisms may be activated. To isolate vasodilatory onset, the current study investigated the onset of exercise hyperemia in an exercise-to-exercise (E-E) transition where no further increase in muscle pump contribution would occur. Eleven subjects lay supine and performed a step increase from rest to 3 min of mild (10% maximal voluntary contraction; MVC), rhythmic dynamic forearm handgrip exercise, followed by a further step to moderate exercise (20% MVC) in each of arm above (A) or below (B) heart level. Beat-by-beat measures of brachial artery blood flow (Doppler ultrasound) and blood pressure (arterial tonometry) were performed. We observed an immediate increase in forearm vascular conductance in E-E transitions, and the magnitude of this increase matched that of the R-E transitions within each of the arm positions (A, E-E 52.8 ±10.7 vs. R-E 60.3 ±11.7 ml.min-1.100 mmHg-1, P = 0.66; B, E-E 43.2 ±12.8 vs. R-E 33.9 ±8.2 ml.min-1.100 mmHg-1, P = 0.52). Furthermore, changes in forearm vascular conductance were identical between R-E and E-E transitions over the first 9 contraction/relaxation cycles in condition A. The immediate and identical increase in forearm vascular conductance in rest-to-exercise and exercise-to-exercise transitions within arm positions provides strong evidence that rapid vasodilation contributes to immediate exercise hyperemia in humans. Specific vasodilatory mechanisms responsible remain to be determined.
This article has been cited by other articles:
|
|
 |
|
  J. Padilla, R. A Harris, L. D Rink, and J. P Wallace Characterization of the brachial artery shear stress following walking exercise Vascular Medicine, May 1, 2008; 13(2): 105 - 111. [Abstract] [PDF]
|
|
|
|
 |
|
 K. L. Walker, N. R. Saunders, D. Jensen, J. L. Kuk, S.-L. Wong, K. E. Pyke, E. M. Dwyer, and M. E. Tschakovsky Do vasoregulatory mechanisms in exercising human muscle compensate for changes in arterial perfusion pressure? Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H2928 - H2936. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. L. Armstrong, A. K. Dua, and C. L. Murrant Potassium initiates vasodilatation induced by a single skeletal muscle contraction in hamster cremaster muscle J. Physiol., June 1, 2007; 581(2): 841 - 852. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. L. Armstrong, A. K. Dua, and C. L. Murrant Time course of vasodilation at the onset of repetitive skeletal muscle contractions Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R505 - R515. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. M. Rogers, N. R. Saunders, K. E. Pyke, and M. E. Tschakovsky Rapid vasoregulatory mechanisms in exercising human skeletal muscle: dynamic response to repeated changes in contraction intensity Am J Physiol Heart Circ Physiol, September 1, 2006; 291(3): H1065 - H1073. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. J. Harper, L. F. Ferreira, B. J. Lutjemeier, D. K. Townsend, and T. J. Barstow Human femoral artery and estimated muscle capillary blood flow kinetics following the onset of exercise Exp Physiol, July 1, 2006; 91(4): 661 - 671. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. L. MacPhee, J. K. Shoemaker, D. H. Paterson, and J. M. Kowalchuk Kinetics of O2 uptake, leg blood flow, and muscle deoxygenation are slowed in the upper compared with lower region of the moderate-intensity exercise domain J Appl Physiol, November 1, 2005; 99(5): 1822 - 1834. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. S. Kirby, R. R. Markwald, E. G. Smith, and F. A. Dinenno Mechanical effects of muscle contraction do not blunt sympathetic vasoconstriction in humans Am J Physiol Heart Circ Physiol, October 1, 2005; 289(4): H1610 - H1617. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Sheriff, P. S. Clifford, J. J. Hamann, Z. Valic, and J. B. Buckwalter Point: The muscle pump raises muscle blood flow during locomotion J Appl Physiol, July 1, 2005; 99(1): 371 - 375. [Full Text] [PDF]
|
|
|
|
|
|
N. R. Saunders, K. E. Pyke, and M. E. Tschakovsky Dynamic response characteristics of local muscle blood flow regulatory mechanisms in human forearm exercise J Appl Physiol, April 1, 2005; 98(4): 1286 - 1296. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. R. Saunders, F. A. Dinenno, K. E. Pyke, A. M. Rogers, and M. E. Tschakovsky Impact of combined NO and PG blockade on rapid vasodilation in a forearm mild-to-moderate exercise transition in humans Am J Physiol Heart Circ Physiol, January 1, 2005; 288(1): H214 - H220. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
