blood lactate accumulation and removal
DESCRIPTION
Blood Lactate Accumulation and Removal. Effects on Blood Lactate Concentration. Lactate Response to Prolonged Exercise (70% of VO 2max ). (Kolkhorst & Buono, Virtual Exercise Physiology Lab , 2004). Lactate Response to Prolonged Exercise. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/1.jpg)
Blood Lactate Accumulation and Removal
Effects on Blood Lactate Concentration
![Page 2: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/2.jpg)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 30 60 90 120 150 180
Time (min)
La
cta
te (
mM
)
Lactate Response to Prolonged Exercise(70% of VO2max)
(Kolkhorst & Buono, Virtual Exercise Physiology Lab, 2004)
![Page 3: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/3.jpg)
Lactate Response to Prolonged Exercise
![Page 4: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/4.jpg)
Lactate Response to Incremental Exercise(endurance-trained athlete)
0
2
4
6
8
10
12
0 10 20 30 40 50 60 70 80 90 100
% of VO2max
La
cta
te (
mM
)
(Kolkhorst & Buono, Virtual Exercise Physiology Lab, 2004)
![Page 5: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/5.jpg)
Anaerobic Threshold: Does it Exist?(or blood lactate inflection point?)
• Wasserman et al. (1973) proposed that muscle became hypoxic at higher intensities and thus produce ATP and lactate anaerobically as well as VE
• Challenges to Wasserman theory– McArdle's syndrome patients lack phosphorylase
• still demonstrate VT
– does muscle become hypoxic?– are there other factors that explain the sudden
increase in blood La?
![Page 6: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/6.jpg)
Muscle intracellular PO2 and net lactate release. Note that PO2 remains above critical mitochondrial O2 tension (1 torr).
Relationship between mitochondrial VO2 and PO2. Critical mitochondrial PO2 is around 1.0 torr.
Mitochondrial PO2 during exercise
![Page 7: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/7.jpg)
Motor Unit Recruitment Pattern -- Size Principle
![Page 8: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/8.jpg)
La and EPI Response to Exercise
La
EPI
![Page 9: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/9.jpg)
Metabolic Fate of Lactate
![Page 10: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/10.jpg)
Lactate Shuttle
![Page 11: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/11.jpg)
Cori Cycle
![Page 12: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/12.jpg)
Influence of exercise intensity on rate of blood La clearance during recovery
![Page 13: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/13.jpg)
Metabolic Fate of Lactate
• During exercise:– ~¾ oxidized by heart, liver, and ST fibers
• During recovery:– oxidized by heart, ST fibers, and liver (1 fate)– converted to glycogen– incorporated into amino acids– La metabolism depends on metabolic state
![Page 14: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/14.jpg)
Fate of lactate under three conditions 4 hr after injection. Note that oxidation is the 1 pathway of removal.
![Page 15: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/15.jpg)
Effect of Altitude on La Response
At altitude:• blood [La] is higher at same absolute
workloads• muscle blood flow similar at same absolute
workloads • La threshold occurs at same relative intensity• EPI threshold occurs earlier at altitude• Lactate paradox – peak [La] is less under
hypoxic conditions than at normoxia
![Page 16: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/16.jpg)
Determining lactate turnover during exercise: tracer methodology
• use naturally occurring isotopes– 13C and 2H isotopes most commonly used
• pulse injection tracer technique– isotopically-labeled La added to blood in
single bolus– concentration measurements taken over
time– rate of concentration decline represents
turnover rate
![Page 17: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/17.jpg)
Pulse injection tracer technique
![Page 18: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/18.jpg)
Continuous-infusion tracer techniques
• Continuous-infusion technique – isotopically-labeled La added at increasing rate until
equilibrium point is reached• La appearance = La removal
• Primed continuous-infusion technique– priming bolus of isotopically-labeled La added initially
• speeds time to reach equilibrium
– remaining isotopically-labeled La added at continuous, constant rate
– [isotope] depends on rate of infusion and volume of distribution (estimated)
![Page 19: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/19.jpg)
Continuous infusion tracer technique
![Page 20: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/20.jpg)
Primed continuous-infusion technique(used by Stanley et al. and MacRae et al.)
• turnover rate = appearance - disappearance• Ra dependent on:
– volume of distribution– arterial [La]
• Rd = Ra minus arterial [La]• metabolic clearance rate (MCR) = Rd / [La]
– calculates La clearance rate relative to arterial [La]– increasing MCR indicates Rd is dependent upon [La]
![Page 21: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/21.jpg)
Read one of the following articles for next Tuesday
Holden, S.-MacRae, S.C. Dennis, A.N. Bosch, and T.D. Noakes. Effects of training on lactate production and removal during progressive exercise in humans. J. Appl. Physiol. 72: 1649-1656, 1992.
Stanley, W.C., E.W. Gertz, J.A. Wisneski, D.L. Morris, R. Neese, and G.A. Brooks. Systemic lactate turnover during graded exercise in man. Am. J. Physiol. 249 (Endocrinol. Metab. 12): E595-E602, 1985.
![Page 22: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/22.jpg)
Lactate response to graded exercise(Stanley et al., JAP, 1985)
• Ra and Rd exponentially related to VO2
• linear relationship between arterial [La] and Ra
• curvilinear relationship between arterial [La] and Rd
![Page 23: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/23.jpg)
Rates of blood lactate appearance (Ra) and disappearance (Rd) during graded exercise
before and after training
MacRae et al., JAP, 1992
![Page 24: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/24.jpg)
Training adaptations to lactate kinetics(MacRae et al., JAP, 1992)
• submaximal Ra by training• peak Ra similar regardless of training status• at same relative intensities, Ra was at <60%
and similar at >60% • Rd by training• peak Rd • at same relative intensities, Rd was similar at
<60% and at >60%• MCR at higher exercise intensity and with
training
![Page 25: Blood Lactate Accumulation and Removal](https://reader035.vdocuments.net/reader035/viewer/2022062322/5681449a550346895db1456c/html5/thumbnails/25.jpg)
Effect of training on blood lactate response
65% pre-training
65% post-training – same relative workload
45% post-training – same absolute workload
45% pre-training