Now that you have your lactate threshold heart rate
what do you do with it? Using the chart below calculate
your heart rate based upon the lactate threshold heart
rate you established in the field test.
% of LT
% of LT
1 - Active Recovery
2 - Endurance
3 - Tempo
4 - Subthreshold
5a - Suprathreshold
5b - Aerobic Capacity
5c - Anaerobic Capacity
Zone 1: Active Recovery: Research indicates
that after hard workouts, very easy workouts
accelerate recovery more than complete rest.
Easy aerobic training stimulates circulation
which speeds up healing of tissues that have
been damaged by hard training. For this purpose,
it is absolutely critical to maintain an intensity
that is enough to increase blood circulation
and to trigger a growth hormone release, but
not intense enough to increase the damage from
which the athlete must recover.
Zone 2: Aerobic Threshold (AeT): Training
at this intensity maximally overloads the
muscle fibers, increasing endurance. Since
these fibers produce most of the energy and
create most of the power for any endurance
event lasting four minutes or longer, workouts
at this intensity should comprise most of
your training. Note that training in this
the most effective way to overload the endurance
fibers and that training above this intensity
is less beneficial for this purpose.
At low intensities, fat is the primary fuel
for exercise. Obviously, this is important
for body-fat reduction but it is also important
when training for events of two hours or
longer. The body stores one to two thousand
as carbohydrate, but even the leanest athlete
stores many thousand calories as fat. Carbohydrate
will always run out before fat. Therefore,
fat is the ideal fuel for long distance racing.
Training at this intensity increases fat
burning and decreases carbohydrate burning.
Athletes training for shorter events with
higher intensity need to perform much of
at this level to stimulate improvements in
the slow-twitch fibers. Performing basic
aerobic workouts at too high intensity reduces
effectiveness of harder workouts on subsequent
days by fatiguing and/or depleting carbohydrate
stores of the fast twitch fibers.
This zone will feel very easy - you may find
it hard to believe that this is training
at all! For many people, the most difficult
of following a systematic heart-rate training
program is keeping the intensity low enough
on easy days and long workouts. Staying in
zone 2, when appropriate, is critical for
everyone. Going too hard on easy days is
the #1 cause
Zone 3: Tempo Training In zone 3, the body
is still functioning aerobically. The effort
is comfortable, conversation is possible,
and burning in the legs and shortness of
are minimal. Still, the intensity is too
high for maximal stimulation of the slow-twitch
muscle fibers and for fat-burning. As intensity
increases from zone 2 to zone 3, the circulatory
system cannot get proportionally more oxygen
to the muscles. Since it takes more oxygen
to burn one calorie from fat than from carbohydrate,
more carbohydrate and less fat will be burned.
Zone 3 training does increase glycogen storage
in the muscles and has a slight aerobic benefit,
but the cost is high for recovery before
workout. Since training in zones 4 and 5 burns
nearly 100% carbohydrate, it is critical that
carbohydrate stores be full on these hard days.
At zone 3 intensity, you really aren’t
going hard enough to make yourself faster,
but you are going hard enough to deplete yourself
for tomorrow’s workout.
Zone 4: Lactate Threshold Lactate Threshold
(LT or AT for anaerobic threshold) is the
highest intensity at which the body can recycle
acid as quickly as it is produced. In zone
4, the aerobic and anaerobic systems are
working together in balance to provide energy
Anaerobic metabolism is slow enough that
lactic acid, the substance that makes muscles
during hard exercise, does not accumulate.
At this intensity, the athlete is working
very hard, but the exercise can be maintained
lactic acid levels in the blood and muscles
are steady, not increasing. Increasing the
intensity just slightly causes lactic acid
to build up and brings premature fatigue
and dramatically delays recovery from the
Training near lactate threshold decreases
the amount of lactic acid being produced and
lactate removal at a given output. At this
intensity we train the FOG fibers to produce
less lactic acid and we train the slow twitch
fibers to burn more acid, both of which raise
the speed or wattage of lactate threshold,
a primary goal of training. Since lactic acid
levels are controlled, recovery from this type
of training is quicker than from other high-intensity
training methods, therefore Zone 4 training
has the best Cost : Benefit ratio of any type
The lower end of Zone 4 is best for long
(20-60 minutes) tempo segments at a very
The primary function of training in low zone
4 is to increase the endurance of the FOG
muscle fibers, which extends the duration
is able to maintain anaerobic threshold intensity.
The higher end of Zone 4 is best for cruise intervals
or moderately long (12-30 minutes) tempo segments.
Cruise intervals are short tempo segments of four
to six minutes with one to two minute recovery segments
at a lighter intensity between efforts. The primary
benefit of high zone 4 training is to increase the
power output of the FOG fibers.
Zone 5a: Super-threshold Training: In zone 5a, the
energy demand is too high to be met mostly through
aerobic metabolism. Anaerobic metabolism increases
to the point where lactic acid accumulates in the
muscles and blood. At this intensity, lactic acid
slowly, so this intensity may be sustained for a
relatively long period. This is effective work since
such as a 40K time trial or a 10K running race occur
at this intensity. Workouts at this intensity are
also effective for increasing lactate tolerance,
of the muscle to continue to produce speed and power
effectively despite the accumulation of acid.
5b : Aerobic Capacity Training: In zone 5b,
lactic acid builds up quickly, so this intensity
cannot be sustained for long periods. At this intensity,
the aerobic system is working at 95 - 100% of maximum.
This training takes two forms:
Interval Training, zone 5b efforts of one to three
minutes followed by short periods of low level exercise
which allow only partial recovery from the repetition.
Usually the work to rest ratio is between 1:1 and
Repeat Training, zone 5b efforts of 3 - 7 min with
longer periods of low level exercise or rest which
allow complete recovery from the repetition. The
work to rest ratio is usually below 1:1.
Zone 5 training is a very effective means of increasing
endurance performance, but, because lactic acid levels
become extremely high, this type of training requires
extensive recovery between workouts. Zone 5 training
carries a high cost and benefit.
Make sure to include these workouts when appropriate,
but be just
as sure not to overdo them. A little bit goes a long
way. Aerobic capacity training is a powerful tool, but
a little bit goes a long way.
Zone 5c Anaerobic Capacity Training: While
aerobic conditioning is critical to endurance performance,
situations arise in races where the energy cost far
exceeds the athlete’s aerobic capacity. These
situations call for high levels of anaerobic energy
production followed by a period of recovery. Training
for short durations in zone 5c prepares the athletes
for these demands.
addition to increasing an athlete’s sprint
power, training at this intensity will improve an
athlete’s economy, or efficiency. Every athlete
should take this kind of training seriously as it
take a long time to recover from these workouts.
There are numerous books that cover heart rate monitor
training in detail and this article is intended to
give the basics for heart rate monitor training.
For a much more in depth guide to using a heart rate
monitor and a great resource in general I recommend
reading Joel Friel’s, “Triathlete’s
Many of the ideas in this
article are based upon Joe’s training philosophy.
Thanks to Ken Mierke of Fitness Concepts for allowing
me to use his descriptions of training zones.