"The time is always right to do what is right"
Dr. Martin Luther King Jr.
It appears to me that everyone can agree that training with a heart
rate monitor is a good idea. And they seem to agree that the majority
of pre season training should be aerobic to build a strong aerobic base
with a smaller percentage time spent training at or above threshold.
But what too few can agree upon is how you locate that crossover point.
So here I wade into the dark realm of "determining threshold", a
discussion as congenial as a cancer society/tobacco industry debate
Let's start with something that almost everyone can agree upon: your
maximum heart rate is a genetically set number that cannot be changed
but your anaerobic threshold (AKA aerobic threshold, or lactate
threshold) is something that can be improved upon. I want to keep this
simple, so let's define some terms: max heart rate (max HR) is pretty
straightforward. It's your ceiling - it's as hard as you can go. Your
threshold (AT), on the other hand, is a point at which the body
switches from the aerobic energy system to the anaerobic energy system.
It may help to think of these as two different engines in the body. The
aerobic engine is an efficient, environmentally friendly machine that
can run all day. The aerobic engine runs pretty much on oxygen and fat
(of which the body has plenty) and produces waste that is pretty easy
to deal with like sweat, urine, carbon dioxide and a small amount of
lactic acid. The anaerobic engine is another story. It's more like the
engine you would take to the quarter mile drag strip - lots of power,
but it won't last long. It runs pretty much on stored glycogen
(glucose) alone and produces some ugly amounts of lactic acid as waste.
So much lactic acid, in fact, that the body can't flush itself of the
toxin fast enough and performance begins to decrease.
A triathlete needs an efficient energy system that can last a long
time. Even a sprint distance race that lasts as little as an hour is a
race that predominantly uses the aerobic energy system. By training the
aerobic system to be the best that it can be the athlete will push the
threshold boundary farther away. The results are simple; you get
faster. To train the aerobic engine you need to know where your AT is
and you need to stay under it. A heart rate monitor can tell you what
your pulse rate is but you need to first determine what number
represents your threshold. This is where the arguments can really get
heated. There are several methods to finding your AT and they seem to
be dependent on these factors: Time, Expense, Accuracy - choose any
two. The most accurate results come from a lab, and after you get an
appointment you're going to pay anywhere from $120 to $600 for the
test. The quick and easy methods are cheap but the results can differ
greatly. I submit my own personal info as an example:
My AT was determined by a lab last year to be at 161 beats per min (bpm).
One of the oldest methods to determine max heart rate is to take 220
and subtract your age. For me that would be 220-31=189 which is nice
but as stated earlier, everybody agrees that max heart rate is a pretty
useless number since its genetically set and I can't do thing to
improve it. I've got a half a dozen books in my office that claim
lactate threshold is approximately 65 to 90 percent of max. That broad
spectrum tells me that my AT is some where between 122 bpm and 170 bpm.
The difference in effort between those numbers is huge and would not
result in very specific training.
A more complicated equation is the Karvonen Formula. Here again we
start with 220 less my age (31) and get 189, then we subtract my
resting heart rate (42) and get 147. Then I take that number and
multiply by the desired intensity level. If AT lies between 65 and 90
percent then we will use those intensity levels; 65% of 147 is 96 and
90% of 147 is 132. Then to complete the formula we add the resting
heart rate back on and determine that my AT is somewhere between 138
and 174. Better, but still too much gap.
When Mark Allen spoke to the TZ crew last month he said that to
determine your AT all you needed to do was subtract your age from 180
and then tweak it by subtracting 10 if you're a couch potato,
subtracting 5 if you're a weekend warrior, leaving the result unchanged
if you workout 3 to 4 times per week for the last several months or add
5 if you have been training consistently for the last 2 years. That
would put my AT at 154. How could anyone argue with Mark, he's a super
nice guy and judging from his resume, this clearly works for him.
There is agreement that most athletes can maintain a heart rate that is
at (or slightly above) their AT for a 30 to 45 minute workout. A great
way to judge your AT would be to run a 10K or ride a one hour time
trial and take your average heart rate for that effort. What is nice
about this method is that you can revisit the test and change your
training as you improve your AT. This method also settles another
argument, the discussion over weather or not your AT remains the same
for all three sports. This test will give you results specific for you
on your bike or your run. Wearing a monitor during swim training isn't
very functional but if you are really set on knowing your swim
threshold then swim a 3000 yard or meter time trail and get your 100
yd/m average - that will be your threshold pace for a "hundred" and can
be put to use for training.
Regardless of the number you get or how you got it, making an effort
can help your training. On those days when youre alone and motivation
is needed, the heart rate monitor and an assumed number can be a real
driving force. And on the other side of the coin, if you're on a group
ride or run and you feel like your killing yourself to keep up with the
hammer heads - that monitor and estimated AT can be the thing that
helps make the decision to slow down to a more logical zone. Heart rate
can be influenced by heat, hydration, fatigue, overreaching,
over-training, and other factors. Its just a tool designed to assist
your training, try not to become a slave to the device and remember to
listen to how you are feeling first. ?