Outline
• Basis for muscle contraction
• Metabolic pathways for the generation of
energy for muscle contraction
• Lactate production and the lactate threshold
• Establishing the Lactate threshold in the lab
• Classification of training intensities
• Prescribing individual training intensities
based on the lactate threshold
• The use and accuracy of handheld lactate
meters in a club setting
• Lactate threshold Special Populations
Prescribing training intensities
based on the Lactate
Threshold
David Ashley
School of Health and Human Performance
Dublin City University
Firstly I’d like to thank The Coach Education Committee for inviting me here to
speak today, in particular I’d like to thank Pat McInerney for all his hard work in
putting this conference together but especially for giving me such an easy act to
follow. Thanks Pat, I owe you one.
So what we’re going to do in this session is try and arrive at an understanding of
how Individual exercise training zones are set.
To do this, we will briefly examine the energy source and mechanisms by which our
muscles are able to contract and perform work
We are going to look at an important by product of exercise called lactate, and
examine how intense exercise results in an excess build up of lactate, which limits
performance
We’ll then have a look at how we can measure the point or “threshold” at which
lactate begins to accumulate in the laboratory setting
I’ll touch on some definitions used to describe training zones
I’ll also introduce some of the new portable handheld devices for measuring lactate
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Chemical energy from food to Mechanical
Energy for muscle contraction
Food Molecules
The breakdown of ATP provides
the energy currency for all forms
of biological work
Contains a lot of energy
Energy stored during the
breakdown of food is used
to manufacture a chemical
compound
ATP
Mechanical Work
Stored in muscle cells
Cells use the energy released
from the breakdown of ATP to
perform work
The food we eat is packed with chemical energy!
The breakdown of the high energy molecule Adenosine triphosphate is the basic
cellular energy currency for all biological work
(Carbohydrate, fat, protein and alcohol)
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Bioenergetics
Energy for muscle contraction
In a chemical reaction ATP looses a phosphate to become
ADP, this results in a release of energy
ENERGY
ATP
ADP
Pi
Well how does this molecule ATP work to facilitate muscle contraction?
If we could isolate a particular muscle, in this case the bicep
We would see that
Muscles are connected to bones via connective tissue called tendons
And as we take a closer look we would see that this muscle is composed of bundles
of muscle fibres, which in turn are composed of many muscle cells.
These muscle cells are made up of thick filaments in red named myosin and thin
filaments called actin
The interaction of Hundreds of thousands of these filament complexes allows for the
basic mechanism of muscle contraction
Release of the the bridge between myosin and actin requires binding of ATP. After
Atp binds it is split to ADP and inorganic Phosphate the energy derived from this
reaction is used to cock the cross bridge in preparation for the power stroke. The
power stroke is initiated when the myosin cross bridge binds to actin. The cycle
begins again when another ATP binds to myosin
If you can imagine thousands of these reactions occurring every millisecond in
hundreds of thousands of such units during a muscle contraction you can imagine
the net effect of pushing off a footstretcher or God forbid raising your hand to ask a
question.
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% of maximum energy production
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Energy Systems for
producing ATP
ATP stored in Muscles
2 sec
10 sec
1 min
2 min
2hrs
I’d like to try a little experiment, it might help to waken everyone up for a minute
Could we get everyone in the room to stand up.
Come on everybody!
Now that you’re standing up, I want you to sit down and stand up again as quickly
as you can 3 times without knocking anybody over
Congratulations! You’ve all managed to completely expend all the ATP you had
stored in your leg muscles before you stood up
The quantity of stored ATP in our muscles is sufficient for about 2-3 seconds
maximal activity
High Jump, Shot put, Hammer, Javelin, Golf Swing
So if ATP is the fuel source for all muscle contraction, then how are we all still alive?
Why haven’t our hearts run out of energy and stopped beating?
How are we replenishing our ATP?
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% of maximum energy production
% of maximum energy production
Anaerobic Alactic System
Stored ATP + Creatine Phosphate
2 sec
10 sec
1 min
2 min
Anaerobic System
2hrs
2 sec
10 sec
1 min
2 min
2hrs
Anaerobic Glycolysis results in the production of energy to make of ATP through the
breakdown of glycogen
The next of energy system that is called on to prodice ATP is that derived from
Creatine Phosphate, (you may have heard of the Creatine supplement which is
used to regenerate ATP.
stored in the muscle cell,
It can provide the energy almost as rapidly as that supplied by the ATP/CP reaction,
however it results in the
So combined together ATP + CP provides enough energy for about 8 seconds of
maximal work and it is the main source of energy for activities which require
maximal bouts of work and the 100 m sprint would be a classical example of this
formation of lactate which acts to inhibit muscle contraction and limit performance.
Together these two systems are called the Anaerobic Alactic System, which means
they do not produce Lactate and they do not require Oxygen
Aerobic System
2 sec
10 sec
1 min
2 min
10
% of maximum energy production
% of maximum energy production
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2hrs
“Rowing performance at
racing speed
requires both aerobic and
anaerobic
processes of energy
production”
2 sec
The Last energy system is the Aerobic system (aerobic literally means "with
oxygen"). It is the main source of energy for activity lasting more than 2 minutes
10 sec
1 min
2 min
2hrs
Well you probably noticed that we haven’t seen any rowers yet in any of these
categories, that’s because in terms of it’s energy demands a rowing race falls
between two stools. It has both a significant aerobic and anaerobic contribution to
its energy requirements
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The Rowing Race
The Rowing Race
• The energy demands of a rowing race require
large force production in the initial strokes to
develop boat speed.
• Lactate inhibits muscle contraction and can be felt
as a burning feeling in the active muscle
• This results in a rapid depletion of ATP and CP
stores
• As the race progresses past 1:30 – 2:00 min it
enters the aerobic phase allowing the rower to
maintain lactate at a “manageable” level
• The requirement for ATP greatly outweighs that
which can be supplied by aerobic metabolism
• Performance can only be maintained by the
anaerobic metabolism of glycogen
• In the final stages the intensity increases forcing
the athlete into another anaerobic phase resulting
in a further increase in lactate
• A by product of the anaerobic breakdown of
glycogen is LACTATE
So if we look at the energy demands of a 2000m rowing generally we’ll observe the
following pattern
And from a physiological perspective this is the great challenge of a rowing race
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Blood Lactate against Watts
20
Untrained
Well Trained
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Energy for a 2000 m race
B lo o d L a c ta te (m m o l)
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14
12
10
8
6
4
ATP-PC
Anaerobic
2
Aerobic
0
60
95
130
165
200
235
(Watts)
270
305
340
375
410
So on average the energy contribution of the 3 energy systems to a 2000m race is
generally
Here we see two lactate profiles from a rower at rower at different times of the year
1- 2 % from Stored ATP and Creatine Phosphate
The green line represents the same rower 5 months later at the end of January,
20 – 25% from Anaerobic glycolysis
You should notice the difference in the workload at which the inflection point in
lactate starts to occur
The profile in red represents that of a an Intermediate Oarsmen at the end of
September
And approximately 75 – 8% from Aerobic Metabolism
Approx 215 Watts In Sept
Approx 290 Watts in January
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Historical development of the
Lactate Threshold
Measuring Lactate Threshold
• 1970s East German Sports Scientist, Alois Mader
noticed that his athletes rapidly became fatigued when
their lactate levels increased above 4 mmol/l
• 1981 Bertil Stolin and Ira Jacobs of the Karolinska
Institute in Stockholm used the term Onset of Blood
Lactate Accumlation (OBLA)
• The Lactate Threshold or OBLA is generally considered
to represent a switch in energy production from primarily
aerobic to mainly anaerobic metabolism
• Today the OBLA is generally considered to occur at 4
mmol/l of blood lactate concentration
• However the OBLA (4 mmol/l) method for deriving the LT
has persisted, probably because it is easier to define.
• 4mmol/L threshold is one of approximately a dozen
methods of describing the anaerobic threshold
Blood Lactate response to exercise of
increasing intesnity
Blood La m/Mol
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4 m/Mol Lactate threshold
4
3
2
1
0
35
45
55
65
75
85
% VO2 max
There are probably over a dozen methods used in the scientific literature for
measuring the lactate threshold, and there are also several methods used even
within performance laboratories
To keep it simple I will use the most straight forward, the workload at which lactate
reaches 4mmol/L
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Measuring Lactate Threshold in the
laboratory
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IARU Training Classifications
So we’re going to watch a short video which will show concept of how the lactate
threshold is measured in a laboratory setting.
Class
Name
Energy
U3
Utilisation 3
Fat
Glycogen
U2
Utilisation 2
Fat
Glycogen
U1
Utilisation 1
AT
Anaerobic
Threshold
T
AN
Duration
Lactate
HR
Rate
<2mmol/l
<75% of max
low
<75%
60-120min
<2mmol/l
>75% of max
low - 20
75-80%
Glycogen Fat
30-60min
2-4mmol/l
>80% of max
18 - 24
80-85%
Glycogen Fat
15-30min
4-6mmol/l
>90% of max
24 - 30
85-90%
Tranport
Glycogen
5-20min
6-10mmol/l
<100% of max
30 - high
90-95%
Anaerobic
Glycogen
5-10min
10-max
mmol/l
100%
high
95-100%
>100%
S
Speed
CP Glycogen
<60sec
reps
up to max
up to 100%
max
PS
Power Strokes
Glycogen Fat
15-30min
4-10mmol/l
>80%
low - high
60-120min
2-6mmol/l
>80%
low - high
GS
General
Strength
CP Glycogen
DS
Dynamic
Strength
CP Glycogen
60-90min
SE
Strength
Endurance
Glycogen Fat
90-120min
Speed
Many of you may recognise this table it was published a couple of years ago by
Rowing Ireland. It describes the several training zones and their energy
contributions. Although the terminology may change they are pretty standard
definitions that are widely used.
The test consisted of 3 minute stages with 1 minute rest periods, each stage gets
progressively more difficult.
We are going to use these definitions to define precisely Aerobic and Lactate
training zones for the athlete tested in the video earlier
The video has been shortened to show just 15 seconds from each stage.
You will note that although Heart Rate is rising progressively there is very little
change in the lactate levels in the initial stages.
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U3
Utilisation 3
200
195
190
185
180
175
170
165
160
155
150
145
140
135
130
125
120
115
110
105
100
Energy
Fat
Lactate
Glycogen
< 2mmol/l
U2
HR
< 75% of max
70 - 75 % of MHR = 133 - 143 bpm
Name
Energy
Lactate
HR
U2
Utilisation 2
Fat
< 2mmol/l
75 -80 % of max
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6
Heart Rate (bpm)
10
8
4
U 3 window in this case
200 – 220 Watts, 133 – 143 bpm
2
0
80
Oxygen utilisation Zone 2
Class
14
Athletes Max HR = 190 bpm
Lactate mmol/l
Heart Rate (bpm)
Oxygen utilisation Zone 3
Name
200
195
190
185
180
175
170
165
160
155
150
145
140
135
130
125
120
115
110
105
100
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440
Glycogen
14
Athletes Max HR = 190 bpm
12
75 % of MHR – 2 mmol/L = 143 – 163 bpm
10
8
6
Lactate mmol/l
U3
Class
4
U 2 Training Window
220 – 280 Watts, 143 – 163 bpm
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2
0
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440
Watts (W)
Watts (W)
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Oxygen Utilisation Zone 1
Name
Energy
U1
Utilisation 1
Glycogen
200
195
190
185
180
175
170
165
160
155
150
145
140
135
130
125
120
115
110
105
100
Fat
AT
Lactate
HR
2 – 4 mmol/l
80 – 85 % of max
Name
Energy
AT
Anaerbic Threshold
Glycogen
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75 % of MHR – 2 mmol/L = 143 – 163 bpm
12
U 1 Training Window
280 – 300 Watts, 160 – 166 bpm
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Heart Rate (bpm)
10
8
4
2
0
80
200
195
190
185
180
175
170
165
160
155
150
145
140
135
130
125
120
115
110
105
100
Lactate
HR
4 - 6 mmol/l
85 – 85 % of max
14
Athletes Max HR = 190 bpm
4 – 6 mmol/L = 165 – 170 bpm
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10
8
AT Training Window
295 – 315 Watts, 165 – 170 bpm
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4
2
0
80
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440
Anaerobic Threshold
Class
Athletes Max HR = 190 bpm
Lactate mmol/l
Heart Rate (bpm)
Class
Lactate mmol/l
U1
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100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440
Watts (W)
Watts (W)
The Utilisation 1 Zone as defined by the IARU classifications has very tight
parameters in terms of Heart Rate and Power Output because by it’s very definition
it’s likely that it crosses the Lactate Threshold and therefore even a small increase
in workload at this intensity will result in an exponential increase in Blood Lactate
Concentration
The Utilisation 1 Zone as defined by the IARU classifications has very tight
parameters in terms of Heart Rate and Power Output because by it’s very definition
it’s likely that it crosses the Lactate Threshold and therefore even a small increase
in workload at this intensity will result in an exponential increase in Blood Lactate
Concentration
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U3
Name
Energy
U3
Utilisation 3
Fat
200
195
190
185
180
175
170
165
160
155
150
145
140
135
130
125
120
115
110
105
100
Glycogen
Lactate
HR
< 2mmol/l
< 75% of max
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12
10
Anaerobic Threshold
Oxygen Utilisation 1
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Oxygen Utilisation 2
6
Oxygen Utilisation 3
Lactate mmol/l
Heart Rate (bpm)
Class
4
2
UT 3
UT 2
UT 1
AT
0
80
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440
Watts (W)
So we can produce a Chart for an athlete like this one which is particularly tailored
for the individual for use on the water. With the important Aerobic to Anaerobic
Zones outlined
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Quick note on Power Outputs at
4mmol/L for Elite athletes
HW
Men
LWT
Men
HWT
Wome
n
LWT
Women
2 mmol
(watts)
340
298
220
211
4 mmol
(watts)
380
340
255
245
Provided by Martin McElroy
Or a similar chart for use on the ergo, with the workloads in watts outlined
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Laboratory based Lactate analyser
€12,000 approx
Sample time approximately 30 – 40 secs
Sample size > 40 µl
Handheld Lactate analyser
€450 approx
<€2.00 per sample strip
Sample time 60 secs
Sample size > 5 µl
Handheld Lactate analyzers have been around for quite a few years and are used in
the laboratory as well as by a few coaches and individual athletes.
Handheld Lactate analyzers work in a similar manner to handheld glucose
analyzers. A small droplet of blood is drawn from a finger prick and the a disposable
one time only use sensor strip is slotted into the device and the blood is
automatically aspirated into the strip. The measurement takes approximately 60
seconds
Lactate Pro pictured on the left of the screen is the most widely used and probably
the best validated
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In rowing both for reasons of comfort and hygiene it is generally more appropriate to
take a sample from the earlobe as the blood from a fingerprick may cause some
discomfort while rowing and some blood may make it’s way on to the handle.
However with the new rubber handles on the Model D ergometers this may make it
easier to clean and disinfect the handle after use
Accuracy of the Lactate Pro
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