I’m going to just jump straight in and hopefully as time goes fill in the more pertinent personal detail and data as and when it seems fit.
Basic Heart Rate Variability (HRV) is the change in time between successive heartbeats (also called inter-beat intervals, R-R intervals, N-N intervals, etc.).
Unlike Heart Rate (HR) that averages the number of heart beats per minute, HRV looks much closer at the small fluctuations of the heart that occur in response to internal and external events.
HRV is a direct link to your Autonomic Nervous System (ANS) and can therefore be used to gain insights into your nervous system, stress and recovery activity.
Your Nervous System in a Nutshell
Your Autonomic Nervous System controls your body’s unconscious processes (with the help of the endocrine system, etc.) such as blood sugar, adrenaline, digestions, pupil dilation, heart rate, and much more. The ANS has two main branches: the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PNS).
The Sympathetic Nervous System controls your body’s “fight or flight” reactions in response to internal or external stressors. It stimulates blood glucose, pupil dilation (to see tigers better), slows digestion/peristalsis, and increases heart rate. The SNS is ideally activated to overcome short term stress situations and typically ignores long term health.
The Parasympathetic Nervous System controls your body’s “rest and digest” responses and is associated with recovery. Parasympathetic activation conserves energy, constricts pupils, aids digestion, and slows heart rate. The PNS is meant to help build for the long term and is needed to grow faster, stronger, healthier.
Both branches are always working and both are needed to maintain homeostasis in your body. With every single heartbeat, your nervous system is saying “slow down – speed up” based on feedback from all your senses, emotions, etc. A healthy nervous system has a balanced but strong push and pull between the Sympathetic and Parasympathetic branches.
So. Polar HR strap, free app, 2:30mins every morning, get information about what’s going on with your ANS. I’ve been taking readings for a short while and do find the information useful, if only to reinforce what my brain and body are telling me about tiredness or overtraining and the like.