Question:
Do heart rate monitors and more specifically aerobic target zones
really indicate when your body is engaged in aerobic activity? I
noticed that if I go into a sauna I can keep my heart rate in my
target zone without any activity!
During a workout, how do you separate heat stress from basic
muscle demands? That is, how do I know if my heart rate is just
responding to my overheating demands from the exercise and not
the muscle demand for more oxygen?
The reason I ask this question is I have noticed that I can keep
my heart rate in my target zone with very little increase in
breathing rate. This would imply that most of the heart rate
increase is due to heat stress. Yes? No?
Answer:
It could be that the target HRs you are using are off for you. If you used any of the formulae that
uses an estimation of max HR, then you can easily be off by 10 beats or so. In a recent review of
max tests of well trained and elite distance runners and triathletes that I did, I found that the
average difference between predicted max (220-age) and achieved max while running was 8.5
beats/minute. The range was -12 to +33 (the + means the predicted was that much higher).
The only way for a "fit person" to use a HR monitor properly is to arrive
at a REAL maximum attainable heart rate, then chose the aerobic zones below
it. Obviously, persons with poor fitness can't go out and try to hit 200
beats per minute with out begging for a heart attack, but any real athlete
who trains daily should be able to safely hit their max.
As a competitive cyclist, I'm 43 years old, and my maximum attainable heart
rate is 207 beats per minute. Obviously, the formula is worthless for me
and many other athletes----the reality is that only sedentary people have
any business believing in the simplistic 220 - your age nonsense.
Once you know your max attainable HR, you will find your anaerobic threshold
somewhere between 90 and 95% of max. Whatever this heart beat is, about 20
beats lower should be the bottom of your aerobic (and fat burning) band,
with the anaerobic threshold being your aerobic ceiling. The only rides you
do (or runs, etc) that are more than 20 beats below your anaerobic threshold
would be recovery rides/runs, which are more of a massage for the
muscle---they won't contribute to aerobic fitness anywhere near as much as
the rides that are within the aeroobic zone. My easy rides for fat burning
are done at a heart rate of 170 to 175 bpm, and on my high intensity days I
try to stay between 178 and 190, with a few surges into 195 or a bit higher
Right on! The best way you do this is through a stress test supervised
Certainly. That doesn't surprise anyone. I guess if you're in a sauna
and cycling, you'll have to guess how much of your increased heart-rate
is due to what, but ordinarily it's not an issue.
The training effect that results from aerobic exercise does not occur as a
result of the increase heart rate per se. What is actually occuring is an
increase in the workload of the overall cardiovascular system, which
results in an increased oxygen uptake. During aerobic exercise the heart
rate can be used as a *gauge* of how much oxygen uptake is increasing--but
only during aerobic exercises. Heart rate increases that occur during
non-aerobic activity (in the sauna, during weight lifting, under stress,
while intoxicated, etc), are *not* indicative of aerobic training.
