The message is out there. (Sometimes it’s overwhelming.) “YOU NEED TO EXERCISE MORE.” This is absolutely a generalization, and “more” should be taken with a grain of salt. Just like all good things, moderation is recommended. Perhaps you are already physically active at healthy levels according to general guidelines. Does this mean that doing more is going to be even more beneficial? Or can it end up being harmful? Consider the following:
The autonomic nervous system is comprised of 2 parts: the parasympathetic and sympathetic systems. The parasympathetic system is in play when the body is relaxed and is sometimes referred to as the “rest and digest” state. The sympathetic system is commonly referred to as the “fight or flight” response and is activated when there is a real or perceived threat to or disruption of the body’s homeostasis (or balanced state). The sympathetic response is meant to be a healthy adaptation to increase our chance of survival when a threat is present. It results in dilated pupils to allow greater visual acuity, shunting blood to the brain and skeletal muscles to prepare for battle or flight and release of hormones designed to aid in survival as well. This is good…and normal…and desired. However, it is not normal when it becomes chronic – or the dominant state of the body.
The body does not know how to differentiate between physical exertion, physical threats, and mental stress, so each of these result in activation of the sympathetic nervous system, and it is possible for an individual to get to a point where they are going hard at it all the time…or worrying constantly…and have difficulty activating the much-needed parasympathetic nervous system. Once activated, the parasympathetic nervous system allows the return of normal levels of hormones, increased blood flow to internal organs and restoration of damaged body tissues. (Restoration of damaged tissues includes the anticipated damage done during physical fitness exercise).
Some signs that your body may not have adequately recovered from exercise are excessive soreness with workouts (not anticipated for the difficulty of completion), loss of appetite or decreased motivation to exercise. If these sound familiar, you may want to consider if you are giving your body enough time to recover and reach the parasympathetic state for achieving homeostasis before activating the sympathetic system again. Some common mistakes that may drive chronic sympathetic system status are waiting to eat after workouts, not eating enough protein, avoiding all carbohydrates and drinking coffee immediately after workouts. (Click for PT Articles – some articles require having an account to view).
One metric used to assess which nervous system state you are in is called heart rate variability. It differs from heart rate (beats per minute) in that it measures the milliseconds between heartbeats. It has been shown that heart rate variability is high when the body is at rest, and it should be low during periods of stress or exercise. Therefore, it is one way to gauge what state you are in. It is typically measured at rest and indicates whether or not the parasympathetic nervous system is engaged as expected. It requires specific equipment to be accurate, but there have been some apps developed to allow tracking of this health metric. You can read more about it Here.
Activating the parasympathetic system is possible with simple techniques such as meditation (including mindfulness, guided meditation, and deep breathing), increasing rest between workouts, being in nature and playing (especially with kids or animals).
Consider learning more and implementing changes if you feel you are lacking in this area. Your physical therapist may be able to help you identify areas in need of attention by assessing your current habits.