TY - JOUR
T1 - Heart rate at lactate threshold and cycling time trials
AU - Dumke, Charles L.
AU - Brock, David W.
AU - Helms, Brock H.
AU - Haff, G. Gregory
PY - 2006/8
Y1 - 2006/8
N2 - The purpose of this investigation was to relate the heart rate and lactate response during simulated cycling time trials to incremental laboratory tests. Subjects (N = 10) were tested for V̇O2max (56.1 ± 2.4 ml·kg-1·min-1) and lactate threshold during incremental tests to exhaustion. Power output and heart rate (HR) at threshold was assessed by 3 methods: lactate deflection point (LaT), onset of blood lactate accumulation (OBLA), and the point on the lactate curve at maximal distance from a line connecting starting and finishing power output (Dmax). Power output determined at these thresholds was 282.1 ± 4.2, 302.5 ± 1.3, and 296.0 ± 1.8 W, respectively, whereas HR was determined to be 88.6 ± 0.01, 92.2 ± 0.01, and 91.0 ± 0.01% of maximum, respectively. Power output and HR were significantly lower for LaT than for the other 2 methods (p < 0.05). On separate visits, cyclists were instructed to perform maximum efforts for 30 and 60 minutes (30TT and 60TT). Lactate, HR, perceived exertion (RPE), and metabolic variables were measured during the time trials. During the 30TT, participants sustained a significantly higher lactate level (5.29 ± 0.3 vs. 3.43 ± 0.3 mmol·L -1, p < 0.001), percentage of maximum HR (%HRmax) (90.3 ± 0.02 vs. 84.6 ± 0.01, p = 0.009), and overall RPE (15.5 ± 0.5 vs. 14.4 ± 0.5, p = 0.009), than during the 60TT. V̇O2 was not significantly different between the time trials; however, V̇CO2 (p = 0.008), ventilation (p = 0.004), and respiratory exchange ratio (p = 0.02) were significantly higher during the 30TT. Correlations were found between HR at LaT (r = 0.78), OBLA (r = 0.78), and Dmax (r = 0.71) for the 60TT, but not for the 30TT. These data suggest that despite a large variability in blood lactate during time trial efforts of 30 and 60 minutes (from 1.8 to 10.8 mmol·L-1), HR was consistently 90% of maximum for the 30TT and 85% for the 60TT. HR during the 30TT was approximated by HR corresponding to OBLA and Dmax, whereas HR during 60TT was approximated by LaT.
AB - The purpose of this investigation was to relate the heart rate and lactate response during simulated cycling time trials to incremental laboratory tests. Subjects (N = 10) were tested for V̇O2max (56.1 ± 2.4 ml·kg-1·min-1) and lactate threshold during incremental tests to exhaustion. Power output and heart rate (HR) at threshold was assessed by 3 methods: lactate deflection point (LaT), onset of blood lactate accumulation (OBLA), and the point on the lactate curve at maximal distance from a line connecting starting and finishing power output (Dmax). Power output determined at these thresholds was 282.1 ± 4.2, 302.5 ± 1.3, and 296.0 ± 1.8 W, respectively, whereas HR was determined to be 88.6 ± 0.01, 92.2 ± 0.01, and 91.0 ± 0.01% of maximum, respectively. Power output and HR were significantly lower for LaT than for the other 2 methods (p < 0.05). On separate visits, cyclists were instructed to perform maximum efforts for 30 and 60 minutes (30TT and 60TT). Lactate, HR, perceived exertion (RPE), and metabolic variables were measured during the time trials. During the 30TT, participants sustained a significantly higher lactate level (5.29 ± 0.3 vs. 3.43 ± 0.3 mmol·L -1, p < 0.001), percentage of maximum HR (%HRmax) (90.3 ± 0.02 vs. 84.6 ± 0.01, p = 0.009), and overall RPE (15.5 ± 0.5 vs. 14.4 ± 0.5, p = 0.009), than during the 60TT. V̇O2 was not significantly different between the time trials; however, V̇CO2 (p = 0.008), ventilation (p = 0.004), and respiratory exchange ratio (p = 0.02) were significantly higher during the 30TT. Correlations were found between HR at LaT (r = 0.78), OBLA (r = 0.78), and Dmax (r = 0.71) for the 60TT, but not for the 30TT. These data suggest that despite a large variability in blood lactate during time trial efforts of 30 and 60 minutes (from 1.8 to 10.8 mmol·L-1), HR was consistently 90% of maximum for the 30TT and 85% for the 60TT. HR during the 30TT was approximated by HR corresponding to OBLA and Dmax, whereas HR during 60TT was approximated by LaT.
KW - Anaerobic threshold
KW - Dmax
KW - Lactate deflection point
KW - Lactate threshold
KW - OBLA
UR - http://www.scopus.com/inward/record.url?scp=33749000583&partnerID=8YFLogxK
U2 - 10.1519/R-17525.1
DO - 10.1519/R-17525.1
M3 - Article
C2 - 16977709
AN - SCOPUS:33749000583
SN - 1064-8011
VL - 20
SP - 601
EP - 607
JO - Journal of Strength and Conditioning Research
JF - Journal of Strength and Conditioning Research
IS - 3
ER -