0
Lactate threshold:
what does it really mean?

Andrew R. Coggan, Ph.D.
Cardiovascular Imaging Laboratory
Washington Univers...
Lactate threshold (LT)
•
•
•
•
•

What is it?
How do you measure it?
Why is it important?
What determines it?
How do you t...
LT – what is it?
Definition
• The exercise intensity at which lactate production
exceeds lactate removal, and thus begins ...
Lactate threshold: the theory
Lactate threshold: the reality

Smith et al., MSSE 29:654-660, 1997
Blood lactate as a function of time
during exercise at a constant intensity
245 W

275 W

310 W

325 W

6
5
4

Time to fat...
Lactate minimum as an estimate of
maximal lactate steady state

Tegtbur, Busse, and Braumann MSSE 25:620-627, 1993
LT: why multiple criteria?
• The concept of a lactate “threshold” is really just a
convenient way of describing, with a si...
LT – why is it important?
• LT is the single most important physiological
determinant of endurance exercise performance.
•...
Relationship of performance to LT
when VO2max is constant

Coyle et al., J Appl Physiol
64:2622-2630, 1988
Relationship of muscle glycogen use
to LT when VO2max is constant
LT – what determines it?
Many factors
•
•
•
•

Number and/or size of muscle mitochondria
Fiber type/motor unit recruitment...
Characteristics of human slow and fast
twitch muscle fibers
RAMPLIKE RECRUITMENT OF FIBERS
Fiber type recruitment as a function of
exercise intensity
100
Total

80
60

Type I
a
d
t
u
c
s
r
e
b
i
f
%
i
c
r
x
f
t
e
...
Effect of mode of
exercise on LT in
trained cyclists

Coyle et al., J Appl Physiol
64:2622-2630, 1988
Training-induced changes in LT over the
course of a season in triathletes

+6%
+10%

Kohrt, O’Conner, and Skinner, MSSE 21...
Changes in lactate and epinephrine as a
function of exercise intensity

Mazzeo and Marshall, J Appl Physiol 67:1319-1322, ...
Physiological responses related to LT
• Muscle glycogenolysis
• Glucose uptake,
production, &
concentration
• Plasma K+
• ...
LT – how do you train it?
• At least/especially in untrained persons, training
at a wide range of intensities and duration...
Effect of continuous versus interval
training on VO2max and citrate
synthase activity

Gorostiaga et al. Eur J Appl Physio...
Effect of continuous versus interval
training on blood lactate
concentration during exercise
Continuous exercise
Before
tr...
The “sweet spot”?
100
90

Arbitrary units

80

L2
Training effect
(increase in threshold power)
L1

L4

L3

L5

L6

70
60
...
Key Points
Lactate threshold (LT)
 is, at least in theory, the exercise intensity at which
lactate production exceeds lac...
Key Points (continued)
Lactate threshold (LT)
 provides a measure of a person’s metabolic fitness,
as opposed to their ca...
Key Points (continued)
Lactate threshold (LT)
 responds rapidly (at least initially) to training at a
wide variety of int...
Upcoming SlideShare
Loading in...5
×

Lt what does it really mean

1,014

Published on

Webinar for USA Cycling Coaching Education program.

0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
1,014
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
54
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Transcript of "Lt what does it really mean"

  1. 1. Lactate threshold: what does it really mean? Andrew R. Coggan, Ph.D. Cardiovascular Imaging Laboratory Washington University School of Medicine St. Louis, MO 63110
  2. 2. Lactate threshold (LT) • • • • • What is it? How do you measure it? Why is it important? What determines it? How do you train it?
  3. 3. LT – what is it? Definition • The exercise intensity at which lactate production exceeds lactate removal, and thus begins to accumulate in muscle and hence in the blood. Related concepts • OBLA, MLSS, lactate minimum, individual anaerobic threshold, ventilatory (anaerobic) threshold, critical power, etc.
  4. 4. Lactate threshold: the theory
  5. 5. Lactate threshold: the reality Smith et al., MSSE 29:654-660, 1997
  6. 6. Blood lactate as a function of time during exercise at a constant intensity 245 W 275 W 310 W 325 W 6 5 4 Time to fatigue @ 310 W: 58 min 3 ) / m ( a L H d o l B 2 1 0 0 2 4 6 Time (min) 8 10
  7. 7. Lactate minimum as an estimate of maximal lactate steady state Tegtbur, Busse, and Braumann MSSE 25:620-627, 1993
  8. 8. LT: why multiple criteria? • The concept of a lactate “threshold” is really just a convenient way of describing, with a single number, the non-linear relationship between lactate concentration and exercise intensity.
  9. 9. LT – why is it important? • LT is the single most important physiological determinant of endurance exercise performance. • Many physiological responses to exercise are more closely related to metabolic fitness (i.e., LT) than they are to cardiovascular fitness (i.e., VO2max).
  10. 10. Relationship of performance to LT when VO2max is constant Coyle et al., J Appl Physiol 64:2622-2630, 1988
  11. 11. Relationship of muscle glycogen use to LT when VO2max is constant
  12. 12. LT – what determines it? Many factors • • • • Number and/or size of muscle mitochondria Fiber type/motor unit recruitment Mode of exercise (muscle recruitment) Hormonal response
  13. 13. Characteristics of human slow and fast twitch muscle fibers
  14. 14. RAMPLIKE RECRUITMENT OF FIBERS
  15. 15. Fiber type recruitment as a function of exercise intensity 100 Total 80 60 Type I a d t u c s r e b i f % i c r x f t e s n o 40 Type IIa 20 Type IIb 0 25 50 75 % of VO2max Vollestad et al. Acta Physiol Scand 125:395-405, 1985 100
  16. 16. Effect of mode of exercise on LT in trained cyclists Coyle et al., J Appl Physiol 64:2622-2630, 1988
  17. 17. Training-induced changes in LT over the course of a season in triathletes +6% +10% Kohrt, O’Conner, and Skinner, MSSE 21:569-575, 1989
  18. 18. Changes in lactate and epinephrine as a function of exercise intensity Mazzeo and Marshall, J Appl Physiol 67:1319-1322, 1989
  19. 19. Physiological responses related to LT • Muscle glycogenolysis • Glucose uptake, production, & concentration • Plasma K+ • Plasma NH4+ • • • • • • Pi/PCr (ADPf) • Etc. • Epinephrine • Norepinephrine Growth hormone Cortisol ß-endorphin Ventilation iEMG • Muscle pO2
  20. 20. LT – how do you train it? • At least/especially in untrained persons, training at a wide range of intensities and durations will tend to lead to rapid improvements in LT, but • For trained athletes there may be particular benefit to continuous training at circa-threshold intensities.
  21. 21. Effect of continuous versus interval training on VO2max and citrate synthase activity Gorostiaga et al. Eur J Appl Physiol Occup Physiol 63:101-107, 1991
  22. 22. Effect of continuous versus interval training on blood lactate concentration during exercise Continuous exercise Before training Interval exercise Same Same absolute relative Before training Same Same absolute relative intensity intensity intensity intensity 4.7±1.1 2.5±0.4* 2.5±0.3*† 6.2±0.8 4.1±0.3* 5.8±0.8 4.8±1.0 3.0±0.7* 5.1±0.9 8.8±1.6 4.3±0.4* 9.0±1.3 Continuous training group Interval training group Gorostiaga et al. Eur J Appl Physiol Occup Physiol 63:101-107, 1991
  23. 23. The “sweet spot”? 100 90 Arbitrary units 80 L2 Training effect (increase in threshold power) L1 L4 L3 L5 L6 70 60 50 40 Physiological strain 30 20 10 Maximum duration (volume) 0 40 50 60 70 80 90 100 110 120 Exercise intensity (% of functional threshold power) 130 140 150
  24. 24. Key Points Lactate threshold (LT)  is, at least in theory, the exercise intensity at which lactate production exceeds lactate removal.  can be measured in various ways, all of which provide different, but closely interrelated, values.  is an excellent predictor of endurance exercise performance. (continued)
  25. 25. Key Points (continued) Lactate threshold (LT)  provides a measure of a person’s metabolic fitness, as opposed to their cardiovascular fitness (i.e., VO2max).  determines numerous metabolic and neurohormonal responses to exercise.  in turn is determined by numerous factors, but especially muscle respiratory capacity (mitochondrial content). (continued)
  26. 26. Key Points (continued) Lactate threshold (LT)  responds rapidly (at least initially) to training at a wide variety of intensities and durations, but  may be particularly improved by continuous training in the “sweet spot”.
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×