When embarking on an exercise program it is natural to focus
most of your attention on workouts because without the stimulus of appropriate
exercise done at the correct frequency, intensity and for the right amount of
time you will not make progress. However
it is easy to lose sight of the fact that exercise is a stimulus and stressor
and that progress actually occurs during
recovery from exercise!
So while providing the correct amount of exercise stimulus
is important -- optimizing recovery is as or more important. This is particularly the case as we get older
because our ability to recover from exercise stress tends to decrease as we
age. There are many factors which
affect our ability to recover from and improve from exercise including adequate
sleep, breathing patterns, hydration, nutrition, and mental ability to relax to
name a few.
The art of exercise often comes down to knowing when you are
training to much or too hard and NOT recovering adequately. This is
particularly true as you get older and for serious athletes who must walk a
knife edge between exercising enough and at a high enough intensity and allowing
for adequate recovery.
The great news is that there is a highly accurate way to easily check your recovery status/stress response by monitoring heart rate
variability or HRV for short. HRV
refers to the fact that the time between each heartbeat continuously
varies! The picture at the beginning of this article shows
the variation in time between each beat of the heart measured with an
electrocardiogram. Even though the
time between each heart beat is always varying your heart rate as expressed as
the number of heart beats per minute can be steady at times.
So for example, an average heart rate of 60 beats per minute
(bpm) does not mean that the interval between successive heartbeats is exactly
1.0 sec, instead they may fluctuate/vary from 0.5 sec up to 2.0 sec. During exercise, HRV decreases as heart rate
and exercise intensity increases. HRV also decreases during periods of mental
stress.
As a general rule of thumb we want to see HIGHER Heart Rate
Variability. Higher HRV indicates that
your Autonomic Nervous System (ANS) is in a highly responsive state and able to
quickly adjust to changes and challenges to optimize homeostasis (homeostasis
refers the fact that any living thing must maintain a consistent internal
environment to maintain life so your body must constantly adjust to changes
such as increased temperature, muscle activity, lightness, darkness, etc. to
keep all the cells and organs functioning)
HRV is regulated by the autonomic nervous system (ANS) which
controls the function of our internal organs such as heart, lungs, intestines, level
of arterial tension, etc. The ANS has
two parts: Sympathetic and
Parasympathetic.
The sympathetic nervous system is often considered the
"fight or flight" system, while the
parasympathetic nervous system is often considered the "rest and digest"
system. In many cases, these systems have "opposite" actions where
one system activates a physiological response and the other inhibits it.
Parasympathetic activity decreases heart rate and increases
HRV, whereas sympathetic activity increases heart rate and decreases HRV. Recovery and stress relief is all about increased
parasympathetic activity.
When there
are inappropriately high levels of Sympathetic Activity and low levels of
Parasympathetic Activity – particularly for prolonged periods of time – you cannot
recover from stress and sooner or later you will begin to experience
physiological symptoms and physical performance decrements.
HRV and Heart Disease
When your Parasympathetic Nervous System (PNS) is inhibited your HRV is low and directly influences stress on your heart. An under-active (PNS) and overactive Sympathetic Nervous System (SNS) is a direct cause of high blood pressure, inflammation, and heart disease. In fact research shows that the PNS activity of patients with heart disease is one-third lower, on average, than that of a healthy individual.
Measurement of HRV
Measurement of HRV allows you to know how your body is
responding and adapting to all the stressors in your life including exercise
BEFORE you experience symptoms or a decrease in physical performance. By measuring HRV each morning upon waking
before you rise from bed or eat or drink anything you can very accurately track
your recovery status/stress response. To measure your
HRV you need a chest strap type heart rate monitor that puts out a Bluetooth Signal
so it can connect to your mobile phone.
Most chest strap monitors do put out a Bluetooth Signal. Then download one of several HRV apps for
your phone such as this excellent app: https://elitehrv.com/
Follow the directions to set-up the app and connect your
monitor to the app. Then in morning put
on your monitor and let the app run for 2 minutes or so. Record the HRV numbers and look at them
over a couple of days. It will take a
few days before the numbers will become meaningful. Take notes on your workouts to
see the correlations between your numbers and how you feel. The
numbers are related to you and are not useful unless you can compare it to your
previous data (furthermore, different apps use different algorithms, so the
numbers between apps will be different, as well). You can use recommendations from the app as rough rules
of thumb, but rely mostly on your numbers relative to previous numbers to track recovering and stress response.
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