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Journal of Exercise Physiologyonline
June 2014
Volume 17 Number 3
Editor-in-Chief
Official Research Journal
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of Exercise
Todd Astorino, PhD
Julien Baker,
ISSNPhD
1097-9751
Steve Brock, PhD
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Robert Gotshall, PhD
Alexander Hutchison, PhD
M. Knight-Maloney, PhD
Len Kravitz, PhD
James Laskin, PhD
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Ben Zhou, PhD
Official Research Journal of
the American Society of
Exercise Physiologists
ISSN 1097-9751
JEPonline
Identification of the Lactate Threshold and the Heart
Rate Deflection Point by the Perceived Exertion Curve
Juan Henrique Szymczak Conde1, Tiago Burigo Guimarães Rubio1,
Guilherme Assunção Ferreira1,2, Rogerio Luz Coelho1, Fernando
Roberto de Oliveira2, Raul Osiecki1
1
Center for the Study of Physical Performance, Federal University of
Paraná, Paraná, Brazil, 2Nucleus of Human Movement Studies,
Department of Physical Education, Federal University of Lavras,
Minas Gerais, Brazil
ABSTRACT
Conde JHS, Rubio TBG, Ferreira GA, Luz Coelho R, De Oliveira
FR, Osiecki R. Identification of the Lactate Threshold and the Heart
Rate Deflection Point by the Perceived Exertion Curve. JEPonline
2014;17(3):32-38. The purpose of this study was to identify the lactate
threshold (LT) and the heart rate deflection point (HRDP) by the
perceived exertion curve (DmaxRPE). Nine physically active male
subjects (weight, 77.3 ± 8.9 kg; height, 177.5 ± 3.2 cm; age, 22.2 ±
2.7 yrs, and body fat, 11.3 ± 5.5%) underwent a progressive treadmill
test starting at 6 km·h-1 with 1 km·h-1 increments every 2 min. No
significant differences for heart rate (HR), values of perceived exertion
(RPE), and intensity of the occurrence of HRDP, DmaxRPE, and LT
were found (P≥0.05). Significant correlations of HR, RPE, and
intensity of occurrence of HRDP when compared to LT were found
(HR, r = 0.90; RPE, r = 0.91; and HRDP, r = 0.91; all P≤0.05).
DmaxRPE had low correlations with FC, RPE, and intensity of
occurrence of HRDP (HR, r = 0.14; RPE, r = -0.02; HRDP, r = -0.065;
all P≥0.05), and also with the LT (HR, r = 0.35; PSE, r = 0.19; LT, r =
0.036; all P≥0.05). The results indicate that DmaxRPE has only
reasonable predictive power to determine the LT.
Key Words: Physiologic Transition Thresholds, RPE (Ratings of
Perceived Exertion), HRDP (Heart Rate Deflection Point)
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INTRODUCTION
The lactate threshold (LT) is an important method to improve high intensity performance in endurance
sports, and it is widely used as an indicator of aerobic fitness in athletes. One of the most traditional
and accepted methods for determining LT is the fixed blood lactate of 4 mmol·L-1 (25). However, this
method requires trained personnel and has a relatively high cost. Recently, alternative methods for
identification of LT have been proposed, including the heart rate deflection point (HRDP) (9) and the
ratings of perceived exertion scales (RPE) (10,12).
The HRDP can be identified by a visual inspection of a heart rate (HR) vs. intensity plot. However, in
some individuals, it is not possible to determine the HRDP by this method alone (21). Kara et al. (13),
proposed the Dmax method to identify the HRDP. They showed that the HRDP is generally found at
the point of maximum distance between a linear fit – using the first and last points of this plot – and
the 3rd degree polynomial fit for all the points of the same plot. Several studies have shown that
HRDP can be used to estimate the LT (9,13), regardless of sex, age, and level of training (1).
Borg’s RPE is (2) a widely used psycho-physical method to identify the LT. Some studies indicate that
fixed RPE values have high correlations with LT. In the Borg category-ratio scale (CR-10 scale), the
suggested fixed score is 5 (27). In the 15 points scale, the values are somewhere between 9 and 12
(22). However, the use of fixed scores does not take into account individual biological variability.
Fabre et al. (10) proposed to identify a RPE threshold by the Dmax method (DmaxRPE). These
authors identified the DmaxRPE in similar intensities of LT and showed strong associations between
HR and intensity occurrence of thresholds (10). However, their studies were conducted on a bicycle
ergometer. In addition, HR and intensity of occurrence of DmaxRPE were not compared to HR and
intensity of occurrence of the HRDP. To our knowledge only two studies have assessed the
DmaxRPE (10,12), which used a bicycle ergometer. Thus, it appears that there are no data in the
literature concerning the identification of LT by DmaxRPE and HRDP in a treadmill. The aim of our
study was to find evidence of the validity of DmaxRPE to identify the HRDP and LT while using a
gradual treadmill exercise protocol.
METHODS
Subjects
This study included 9 physically active males (weight = 77.3 ± 8.9 kg, height = 177.5 ± 3.2 cm, age =
22.2 ± 2.7 yrs and body fat = 11.3 ± 5.5%). All subjects were informed about the methodological
aspects as well as the risks and benefits of the study. An informed signed consent was obtained from
each subject. The research procedures were approved by the local Ethics Committee.
Procedures
The subjects underwent a treadmill test (Greenmaster model x-fit7, São Paulo, Brazil) starting at 6
km·h-¹ with increments of 1 km·h-1 every 2 min until voluntary exhaustion. Exhaustion was assumed
when the subjects failed to maintain a certain speed or the HR reached values of ±10 beats·min-1 of
the maximum predicted HR (HRpredict) using the HRpredict = 220 - age (yrs) formula proposed by
Cook (7). Peak velocity (PV) was determined by the rate achieved in the last full stage. When the last
stage was not completed, the PV was considered the last stage corrected (15).
Measurements
The subjects’ HR response was monitored with a portable thoracic monitor (Polar Electro Oy, FI90440, Kempele, Finland). Blood lactate was measured with a validated portable lactometer
(Accutrend Plus, Roche Diagnostics GmbH, Germany) using 25 μL of a blood sample extracted from
34
the right forefinger (19). RPE was measured using the Borg's category-ratio scale (CR-10), with
corresponding descriptors of “nothing at all” (0) and “maximal effort” (10). Each subject was: (a)
familiarized with the RPE scale; (b) instructed to incorporate muscular and central cardiorespiratory
feelings into an overall perception of effort; and (c) was asked to indicate how hard, heavy, and
strenuous the exercise was in a given stage (3).
Heart Rate Deflection Point (HRDP) and Rating of Perceived Exertion Threshold (DmaxRPE)
The HRDF was identified in accordance with procedures proposed by Kara et al. (13). All HR equal to
or greater than 140 beats·min-1 was plotted at each stage versus intensity (i.e., the velocity of the
treadmill). A 3rd degree polynomial fit of all these points was calculated as well as a linear fit of the
first and last points of this same curve. The highest difference between these two lines was a point
called Dmax. The intensity in which this Dmax occurs is defined as the HRDP. The RPE threshold
was identified by the power output at which the largest difference between two lines occurred; that is,
the 3rd-order polynomial fit of the RPE values and the 1st-degree linear fit between the two extreme
values for the RPE curve (DmaxRPE) (10).
Lactate Threshold (LT)
The LT was defined as the intensity in which 4 mmol·L-1 was achieved (i.e., Onset of Blood Lactate
Accumulation - OBLA) (23).
Statistical Analysis
The normality of data was tested using the Saphiro-Wilk test. The only parameter not meeting
normality was the velocity in which DmaxRPE was achieved. Friedman's ANOVA was applied on the
difference between the velocities of occurrence of thresholds. A one-way ANOVA was used to
determine differences between the velocities of occurrence of HRDP, LT, and DmaxRPE. The
correlation of the intensity of occurrence of these thresholds was calculated with the Spearman rank
test. Correlations between HR and RPE scores occurrence of thresholds were determined using a
Pearson test. All significance was set at P≤0.05.
RESULTS
No significant differences (P≥0.05, refer to Table 1) were found between HR, RPE scores, and
intensity of occurrence of the thresholds (HRDP, RPE, and LT) and the percentage of HR peak
(%HRpeak) and percentage of maximum intensity (%Speedmax).
Table 1. Values for HR, Percentage of Maximum Predicted HR (%max HR), Intensity (Speed),
and Percentage of Maximum Intensity (%Speedmax) at the Identification Point of HRDP,
RPET, and LT.
HR (beats·min-1)
%HRpeak
Speed
%Speedmax
HRDP
179 ± 9
91.8 ± 3.9
11.2 ± 1.9
82.5 ± 5.7
DmaxRPE
175 ± 16
89.7 ± 7.6
10.7 ± 1.7
79.1 ± 11
LT
173 ± 7
88.6 ± 2.3
10.3 ± 1.4
76.1 ± 3
Methods
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The PSE values identified in the HRDP, DmaxRPE, and LT were 5.9 ± 2.1, 5.4 ± 1.9, and 4.9 ± 1.3,
respectively. The speed and HR values were significantly correlated between HRDP and LT (P≤0.05).
The speed and HR values were not significantly correlated between DmaxRPE and LT and between
DmaxRPE and HRPD (P≥0.05, see Table 2).
Table 2. Correlation Coefficients between Two Thresholds in Each of Variables (HR, %HRpeak,
RPE, Speed, and %Speedmax).as used.
HR
%HRpeak
RPE
Speed
%Speedmax
HRDP vs. LT
0.91*
0.87*
0.91*
0.90*
0.16
HRDP vs. DmaxRPE
0.14
-0.07
-0.02
0.07
-0.53
DmaxRPE vs. LT
0.35
0.15
0.19
0.04
0.6
DISCUSSION
The main finding of this study was to demonstrate that the Ratings of Perceived Exertion Threshold
(RPET) using the Dmax method (DmaxRPE) is found in similar intensities (speeds) of the Lactate
Threshold (LT) and the Heart Rate Deflection Point (HRDP) when a treadmill incremental test is
performed. To our understanding, this study is the first to use the identification of the DmaxRPE in a
progressive treadmill test to compare it to HRPD.
The RPE is inexpensive and easily performed. This makes it an interesting tool for LT determination
(11,17,24). Fabre and colleagues (10) proposed that the Dmax method could be applied to PSE. The
method takes into account individual biological variations of the subjects, unlike the “fixed scores”
method that is commonly used to determine LT (5 on CR-10 and 9 to 12 of the 15 points RPE scale)
(22,27). In their work, Fabre et al. (10) reported no significant difference between the measured LT
and DmaxRPE. On the other hand, they found the DmaxRPE at lower intensities of exercise
compared to the LT identified by OBLA method (i.e., fixed concentration of 4 mmol·l-1). The authors’
correlation coefficients were high, both between DmaxRPE and LT and DmaxRPE and fixed 4
mmol·L-1 intensities (r = 0.97 and r = 0.93, respectively, P≤0.001). In our findings, the DmaxRPE was
identified in similar intensities to the fixed lactate of 4 mmol·L-1.
In Ferreira and colleagues’ work (12) conducted with carbohydrates, they looked at the manipulation
of carbohydrates (CHO) on performance. They did not observe significant differences in the
physiological variables and the scores between DmaxRPE versus LT. The correlation was significant
only for the power output of occurrence in both thresholds in the control diet (r = 0.75, P≤0.05) while
the low CHO diet had no association (r = 0.04, P≥0.05). This finding demonstrates that the amount of
CHO in the diet has an influence on the LT.
In the studies of Ferreira et al. (12) and Fabre et al. (10), the RPE scores for LT were 3.4 ± 1.9 and
35.3 ± 11.8, respectively. However, in our study the RPE scores observed in LT were 5.44 ± 1.9. The
values found for PSE scores are similar to those found in the study of Zamunér et al. (27). It is
possible that this phenomenon is the related to the ergometer that was used in the different studies.
36
Ferreira and colleagues (12) and Fabre et al. (10) used the cycle ergometer in their studies to identify
LT; whereas, the treadmill was used in the present study. Future studies with different ergometers
should be performed to clarify this point.
The HRDP is a physiological variable often used in the literature. Mikulic et al. (18) found a strong
association between physiological variables measured at the HRDP in rowers and LT (r = 0.79 –
0.96, P≤0.001). Although the method of finding HRDP intensity is still somewhat a controversial topic
(5,13,15,25), it has been widely accepted as a good indicator of LT with HR and intensity at which
HRDP is found being strongly related to physiological transitions (i.e., ventilatory and LT) (6).
Perhaps, these discrepancies in intensities of HRDP are in part due to the diverse research protocols
and the use of different ergometers. Additionally, there appears to be gender differences in the
intensity of occurrence of HRDP (8). These genders difference may be associated with stroke volume
due to differences in the size of the left ventricular cavity in men versus women (20).
CONCLUSION
Our results suggest that DmaxRPE during a treadmill test has a reasonable power of identifying the
Heart Rate Deflection Point and the Lactate Threshold.
Address for correspondence: Tiago Burigo Guimarães Rubio, Departament of Physical Education
of Federal University of Parana, Parana, Brazil. Street Sagrado Coração de Jesus. Phone (55) 41
9678-5332, Email: tiagobgr@gmail.com
REFERENCES
1. Bodner ME, Rhodes EC. A review of the concept of the heart rate deflection point. Sports
Med. 2000;30(1):31-46.
2. Borg E, Kaijser L. A comparison between three rating scales for perceived exertion and two
different work tests. Scand J Med Sci Sports. 2006:16(1):57-69.
3. Borg G. The Borg CR10 Scale. Borg’s Perceived Exertion and Pain Scales. 1998:39-43.
4. Borg GA. Psychophysical bases of perceived exertion. Med Sci Sports Exerc. 1982;14(5):
377-381. Epub 1982/01/01.
5. Bourgois J, Coorevits P, Danneels L, Witvrouw E, Cambier D, Vrijens J. Validity of the heart
rate deflection point asa predictor of lactate threshold concepts during cycling. J Strength
Cond Res. 2004;18(3):498-503.
6. Buchheit M, Solano R, Millet GP. Heart-rate deflection point and the second heart-rate
variability threshold during running exercise in trained boys. Pediatr Exerc Sci. 2007;19(2).
37
7. Cook CB. Maximal oxygen uptake, economy and efficiency. In Eston RG, Reilly T, (Editors).
Kinanthropometry and Exercise Physiology Laboratory Manual: Tests, Procedures and
Data: Exercise Physiology. Routledge, London, 2009. pp. 147-173.
8. Couto. PG, Rodrigues. AP, Júnior. AJF, Silva. SFd, de-Oliveira. FR. Pontos de transição da
frequência cardíaca em teste progressivo máximo. Motriz Revista de Educação Física.
2013;19(2):261-268.
9. Erdogan A, Cetin C, Karatosun H, Baydar ML. Non-invasive indices for the estimation of the
anaerobic threshold of oarsmen. J Int Med Res. 2010;38(3):901-915. Epub 2010/09/08.
10. Fabre N, Mourot L, Zerbini L, Pellegrini B, Bortolan L, Schena F. A novel approach for lactate
threshold assessment based on rating of perceived exertion. Int J Sports Physiol Perform.
2013;8(3):263-270. Epub 2012/09/08.
11. Faulkner J, Eston RG. Perceived exertion research in the 21st century: Developments,
reflections and questions for the future. J Exerc Sci Fit. 2008; 6(1):1-14.
12. Ferreira GA, Osiecki R, Lima-Silva AE, De Angelis-Pereira MC, De-Oliveira FR. Effect of a
reduced-CHO diet on the rate of perceived exertion curve during an incremental test. Int J
Sport Nutr Exerc Metabolism. 2014 (in press).
13. Kara M, Gokbel H, Bediz C, Ergene N, Ucok K, Uysal H. Determination of the heart rate
deflection point by the Dmax method. J Sports Med Phys Fitness. 1996;36(1):31-34. Epub
1996/03/01.
14. Kuipers H, Keizer H, De Vries T, Van Rijthoven P, Wijts M. Comparison of heart rate as a noninvasive determinant of anaerobic threshold with the lactate threshold when cycling. Eur J
Appl Physiol. 1988;58(3):303-306.
15. Kuipers H, Verstappen FT, Keizer HA, Geurten P, Van Kranenburg G. Variability of aerobic
performance in the laboratory and its physiologic correlates. Int J Sport Med.1985;6(4):197201. Epub 1985/08/01.
16. Leger L, Tokmakidis S. Use of the heart rate deflection point to assess the anaerobic
threshold. J Appl Physiol. 1988;64(4):1758-1760.
17. Lima MCS, Junior PB, Gobatto CA, Garcia Junior JR, Ribeiro LFP. Proposta de teste
incremental baseado na percepção subjetiva de esforço para determinação de limiares
metabólicos e parâmetros mecânicos do nado livre. Rev Bras Med Esporte. 2006;12.
18. Mikulic P, Vucetic V, Sentija D. Strong relationship between heart rate deflection point and
ventilatory threshold in trained rowers. J Strength Cond Res. 2011;25(2):360-366.
19. Perez EH, Dawood H, Chetty U, Esterhuizen TM, Bizaare M. Validation of the Accutrend
lactate meter for hyperlactatemia screening during antiretroviral therapy in a resource-poor
setting. Int J Infect Dis. 2008: 12(5): 553-556.
20. Pokan R, Hofmann P, Preidler K, Leitner H, Dusleag J, Eber B, et al. Correlation between
inflection of heart rate/work performance curve and myocardial function in exhausting cycle
38
ergometer exercise. Eur J Appl Physiol Occup Physiol. 1993;67(5):385-388. Epub 1993/
01/01.
21. Ribeiro J, Fielding R, Hughes V, Black A, Bochese M, Knuttgen H. Heart rate break point may
coincide with the anaerobic and not the aerobic threshold. Int J Sports Med. 1985;6(4):220224.
22. Rynders CA, Angadi SS, Weltman NY, Gaesser GA, Weltman A. Oxygen uptake and ratings of
perceived exertion at the lactate threshold and maximal fat oxidation rate in untrained adults.
Eur J Appl Physiol. 2011;111(9):2063-2068.
23. Sjodin B, Jacobs I. Onset of blood lactate accumulation and marathon running performance.
Int J Sports Med. 1981;2(1):23-26. Epub 1981/02/01.
24. Smirmaul BPCS, Dantas JL, Fontes EB, Okano AH, De Morais AC. O nível de treinamento
não influencia a percepção subjetiva de esforço durante um teste incremental. Rev Bras
Cineantropometria Desempenho Hum. 2010;12.
25. Svedahl K, MacIntosh BR. Anaerobic threshold: The concept and methods of measurement.
Can J Appl Physiol. 2003;28(2):299-323.
26. Vachon JA, Bassett DR, Clarke S. Validity of the heart rate deflection point as a predictor of
lactate threshold during running. J Appl Physiol. 1999;87(1):452-459.
27. Zamunér AR, Moreno MA, Camargo TM, Graetz JP, Rebelo AC, Tamburús NY, et al.
Assessment of subjective perceived exertion at the anaerobic threshold with the Borg CR-10
scale. J Sports Sci Med. 2011;10(1):130.
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