| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 School of Sport and Education, Brunel University, Centre for Spors Medicine and Human Performance, Uxbridge, Middlesex, United Kingdom; Hopital Civil and Departement de Physiologie , Service de Physiologie et d, Strasbourg, France
2 and Institut de Physiologie, UPRES EA 3072, Faculté de Médecine, Université Louis Pasteur, Service de Physiologie et des Explorations Fonctionnelles, Hôpital Civil, Strasbourg, France
3 Faculté de Médecine, Université Louis Pasteur, Institut de Chimie Biologique, Strasbourg, France
4 Hôpital de la Robertsau, Centre de Gérontologie, Strasbourg, France
5 and Institut de Physiologie, UPRES EA 3072, Faculté de Médecine, Université Louis Pasteur, Service de Physiologie et des Explorations Fonctionnelles, Hôpital Civil, STRASBOURG, France
6 Hôpitaux Civils, Service de Cardiologie, Colmar, France
* To whom correspondence should be addressed. E-mail: dufourst{at}hotmail.com.
Metabolic demand and muscle mechanical tension are closely coupled during exercise, making their respective drives to the circulatory response difficult to establish. This coupling being altered in eccentric cycling, we implemented an experimental design featuring eccentric vs. concentric constant-load cycling bouts to gain insights into the control of the exercise-induced circulatory response in humans. Heart rate (HR), stroke volume (SV), cardiac output (Q), oxygen uptake (VO2) and electromyographic (EMG) activity of quadriceps muscles were measured in 11 subjects during heavy concentric (heavy CON: 270±13W; VO2=3.59±0.20L/min), heavy eccentric (heavy ECC: 270±13W, VO2=1.17±0.15L/min) and light concentric (light CON: 70±9W, VO2=1.14±0.12L/min) cycle bouts. Using a reductionist approach, the circulatory responses observed between heavy CON vs. light CON (difference in VO2 and power output) was ascribed either to metabolic demand, as estimated from heavy CON vs. heavy ECC (similar power output, different VO2), or to muscle mechanical tension, as estimated from heavy ECC vs. light CON (similar VO2, different power output). 74% of the Q response was determined by the metabolic demand, also accounting for 65% and 84% of HR and SV responses, respectively. Consequently, muscle mechanical tension determined 26%, 35% and 16% of the Q, HR and SV responses, respectively. Q was significantly related to VO2 (r2=0.83; p<0.001) and EMG activity (r2=0.82; p<0.001). These results suggest that the exercise-induced circulatory response is mainly under metabolic control and support the idea that the level of muscle activation plays a role in the cardiovascular regulation during cycle exercise in humans.
This article has been cited by other articles:
|
|
 |
|
  F. N. Daussin, J. Zoll, S. P. Dufour, E. Ponsot, E. Lonsdorfer-Wolf, S. Doutreleau, B. Mettauer, F. Piquard, B. Geny, and R. Richard Effect of interval versus continuous training on cardiorespiratory and mitochondrial functions: relationship to aerobic performance improvements in sedentary subjects Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2008; 295(1): R264 - R272. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Rebuttal from Drs. Richard, Zoll, Mettauer, Piquard, and Geny J Appl Physiol, February 1, 2008; 104(2): 563 - 564. [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
