Int J Sports Med 2007; 28(6): 463-469
DOI: 10.1055/s-2006-924584
Physiology & Biochemistry

© Georg Thieme Verlag KG Stuttgart · New York

Estimation of the Lactate Threshold from Heart Rate Response to Submaximal Exercise: The Pulse Deficit

B. T. Roseguini1 , F. Narro1 , Á. R. Oliveira3 , J. P. Ribeiro1 , 2
  • 1Cardiology Division, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
  • 2Department of Medicine, Faculty of Medicine, Porto Alegre, Brazil
  • 3Exercise Research Laboratory, School of Physical Education, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
Further Information

Publication History

Accepted after revision: July 5, 2006

Publication Date:
16 November 2006 (online)

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Abstract

In this study, we evaluated the validity of a sharp increase in pulse deficit (PD) as a noninvasive index for estimation of the first lactate threshold (LT1) in healthy individuals with various levels of aerobic fitness. Three groups of healthy male subjects participated in the study: 15 sedentary individuals, 14 students of physical education, and 13 competitive athletes. Each subject performed a maximal incremental exercise test on the cycle ergometer for the determination of the LT1, the second lactate threshold, and peak power output. On different days, subjects performed several 8-min bouts of constant-load exercise on the cycle ergometer, corresponding to each of the power outputs of the maximal test, to evaluate PD, which was calculated as the total number of heart beats of the last 4 min minus the total number of heart beats in the first 4 min of exercise. The three groups presented similar blood lactate, heart rate and pulse deficit responses to exercise. For the first power output up to the LT1, PD showed no significant changes. For the three groups, a sharp increase in PD was seen at the intensity immediately above LT1. There was a significant correlation between PD and blood lactate changes from the rest to 4th min of submaximal exercise (r = 0.83, p < 0.05). The power output before a sharp increase in PD detected during constant-load exercise (112 ± 38 W) and the power output corresponding to the LT1 detected during the incremental test (111 ± 37 W, p = 0.323) were similar and strongly correlated (r = 0.99, p = 0.0001). The absolute cut-point value of 25 beats for PD had a sensitivity of 100 %, a specificity of 95 %, and a positive predictive value of 90 % for the detection of LT1. The determination of PD provides an accurate noninvasive estimate of the LT1 in healthy young men with different levels of fitness. One 8-min submaximal exercise bout can establish if an individual is exercising above or below the LT1.

References

MD, ScD Jorge P. Ribeiro

Associate Professor and Chief of Noninvasive Cardiology
Hospital de Clínicas de Porto Alegre

Rua Ramiro Barcelos 2350

90035 - 007, Porto Alegre, RS

Brazil

Phone: + 55 51 99 82 49 84

Fax: + 55 51 21 01 86 57

Email: jpribeiro@cpovo.net