What it is and How it can be used to monitor
Readiness to Train and Recovery Status
The Autonomic Nervous
System
The Autonomic Nervous System consists of two sub-systems.
They are the sympathetic and parasympathetic systems. As most will know both
these systems are central in managing all our involuntary actions and reactions
that take place throughout the various organs of the body. When we are relaxed
and rested our parasympathetic system is balanced with our sympathetic system,
but when for example, you get a fright or have to react within a stressful
situation (the classic ‘flight or fight response’) the sympathetic system takes
over. Various hormones such as adrenaline are pumped through to certain organs
we get ready to move or fight. Our pupils dilate and our heart rate speeds up
and blood is shunted to the muscles so as to flee or to fight.
When danger is over our parasympathetic system stars to
become prominent again and the Vagus Nerve starts to exert its calming influence
on our organs and body reactions.
So during a given day both systems work together to manage
the stress responses and the recovery responses to these stresses. HRV is a
reflection of the balance between these two most important Autonomic or
Involuntary systems. Thus, as we have seen in our last blog, when we measure
the interval between RR waves we get a snapshot of how well our ANS system is
balanced. HRV also tells us if the parasympathetic system is dominating as in
when we feel rested, calm and in control. When the sympathetic system is more
dominant as in when we have to get ready to talk to a group or to meet our
athletes or to start training and competing, then the sympathetic system starts
to kick in and it exerts its important influence in releasing hormones and
speeding up heart rate as well as many other important actions within our body.
When we start to calm down and relax the parasympathetic
system becomes dominant and in this environment recovery starts to happen.
HRV an ideal system
to monitor Training, Competition and Other Stressors
Training load is an important factor to monitor in sport as
it is related to the stress and fatigue and ultimately the adaptation and gains
that are made in performance. Other lifestyle stressors such as sleep or the
lack of it, work and study related stressors, relationships and environment are
all equally if not more important in affecting the balance within the ANS. For
example, a recent study examining the contribution of lifestyle stressors and
training loads in youth sportplayers showed that non-training stressors were
more relevant in accounting for any overtraining that occurred.
HRV when assessed using a short time period (say a 5 minute
period in the morning) gives us a snapshot of the balance within the ANS. When
assessed over a longer duration as during a 24 hour period the balance within
the ANS is well described and we can determine the quality of sleep and
recovery that has taken place at nighttime.
In our next blog we will look at some key studies that
investigated the role of HRV in tracking fatigue and recovery in endurance,
sprint and weightlifting individuals. These studies point to HRV as a very
useful tool in monitoring athletes and players.
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2 comments:
Great information for people looking to monitor their HRV for training and sports purposes!
Cheers, appreciate the feedback!
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