HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 98/5/1660    most recent 00837.2004v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Lepretre, P.-M. Articles by Billat, V. L. Search for Related Content PubMed PubMed Citation Articles by Lepretre, P.-M. Articles by Billat, V. L.

Heart rate deflection point as a strategy to defend stroke volume during incremental exercise

¹Laboratoire d'Etude de la Physiologie de l'Exercice, Department of Sciences and Technology in Sports and Physical Activities, University of Evry Val d'Essonne, Evry, France ²University of Wisconsin-La Crosse, La Crosse, Wisconsin; and ³Sport Medicine Center of the Caisse Centrale d'Activités Sociales, Paris, France

Submitted 4 August 2004 ; accepted in final form 29 November 2004

The purpose of this study was to examine whether the heart rate (HR) deflection point (HRDP) in the HR-power relationship is concomitant with the maximal stroke volume (SV_max) value achievement in endurance-trained subjects. Twenty-two international male cyclists (30.3 ± 7.3 yr, 179.7 ± 7.2 cm, 71.3 ± 5.5 kg) undertook a graded cycling exercise (50 W every 3 min) in the upright position. Thoracic impedance was used to measure continuously the HR and stroke volume (SV) values. The HRDP was estimated by the third-order curvilinear regression method. As a result, 72.7% of the subjects (HRDP group, n = 16) presented a break point in their HR-work rate curve at 89.9 ± 2.8% of their maximal HR value. The SV value increased until 78.0 ± 9.3% of the power associated with maximal O₂ uptake (O_{2 max}) in the HRDP group, whereas it increased until 94.4 ± 8.6% of the power associated with O_{2 max} in six other subjects (no-HRDP group, P = 0.004). Neither SV_max (ml/beat or ml·beat^–1·m^–2) nor O_{2 max} (ml/min or ml·kg^–1·min^–1) were different between both groups. However, SV significantly decreased before exhaustion in the HRDP group (153 ± 44 vs. 144 ± 40 ml/beat, P = 0.005). In the HRDP group, 62% of the variance in the power associated with the SV_max could also be predicted by the power output at which HRDP appeared. In conclusion, in well-trained subjects, the power associated with the SV_max-HRDP relationship supposed that the HR deflection coincided with the optimal cardiac work for which SV_max was attained.

physical work curve break point; left ventricular ejection fraction; cycling graded test

This article has been cited by other articles:

				Rebuttal from Drs. Warburton and Gledhill J Appl Physiol, January 1, 2008; 104(1): 279 - 280. [Full Text] [PDF]

				A. Lucia, C. Foster, P.-M. Lepretre, E. Henriksen, M. Sundstedt, P. Hedberg, C. A. Vella, R. A. Robergs, E. F. Coyle, J. D. Trinity, et al. Stroke volume does/does not decline during exercise at maximal effort in healthy individuals J Appl Physiol, January 1, 2008; 104(1): 281 - 283. [Full Text] [PDF]