The Autonomic Nervous System
Have you ever consciously thought about how your heart beats, how you digest that burger from last night? Or how to keep your blood sugar and body temperature stable? Of course not! This is what your autonomic nervous system (ANS) is doing for you, all day everyday. Your ANS like the word says it regulates everything that is going on in your body on a non-conscious basis.
Rest & Digest vs Fight or Flight
The ANS is divided into two branches:
1. Parasympathetic Nervous system (PNS) commonly referred to as your rest and digest
2. The sympathetic nervous system (SNS) or Fight or flight response.
As you can see in the chart above, these systems have many implications on the body and are complete opposites of each other. The PNS / SNS Continuum It’s not that you are either in a fight or flight state, or a rest and digest state. Instead it is somewhere on a continuum between the two. Where that depends on under how much stress your body currently is and how well you are able to recover from this stress. We can objectively measure where you are on the continuum using HRV.
Heart Rate Variability
HRV emerges from the interplay between these two competing branches. Essentially, in a balanced nervous system, our hearts are constantly getting “mixed messages” — commands to increase heart rate from the sympathetic nervous system and commands to decrease heart rate from the parasympathetic nervous system — these mixed messages cause the resulting heart rate to be in a constant state of fluctuation. HRV measures irregularity in the heart rate. Consider a heart rate of 60 beats per minute; one might take this to imply that the heart is beating consistently once per second, while in actuality, beat-to-beat times could range from 1⁄2 a second to 2 seconds.
Accumulation of stressors
When we think about stress we often think about work or exams etc. Less obvious stressors are, poor nutrition, poor sleep, inflammation, training, but also arguments with your spouse, family tragedies, basically just life in general. The accumulation of these stressors we call the allostatic load.
- Poor nutrition
- Poor sleep
- Nutrient deficiencies
- Intestinal permeability(leaky gut)
- Work stress
- Social stress
When it gets nasty
All this being said, stress doesn’t have to be a bad thing perse. During training for example we put a certain amount of stress on the body in order to make it adapt. For example grow muscle, get stronger, run longer, faster etc. When it gets nasty is when the accumulation of stressors becomes greater than the body’s ability to recover from this stress. In other words the allostatic load becomes bigger than the recoverability.
When it gets really nasty
You probably don’t need to worry too much when this happens every so often. When it really gets problematic is when you’re under these stressors for a prolonged period of time. What happens then is best explained through Dr. Han Seyl’s General Adaptation Syndrome(GAS) model.
- Alarm phase: The body releases stress hormones / mobilizes energy in response to the stressor
- Resistance phase: Prolonged stress leads to stress hormones accumulating to sustain arousal
- Exhaustion phase: Bodies resources are depleted
The crucial phase
It can take months or even years for the exhaustion phase to kick in. But when it does kick in, it can get pretty nasty, burnouts, depression and inability to perceive pleasure to name a few. It is therefore crucial to detect the resistance phase early on and handle appropriately. The problem is that the body will often downregulate your perception of stress until it’s too late. So how can we then detect if we are moving towards the exhaustion phase?
Signs & Symptoms
- Feeling tired / sluggishness
- Decreased performance
- Energy levels are down
- Being sick more frequently then normal
- Can’t get enough sleep
- Disrupted sleep / waking up early
- Difficulty concentrating / impaired cognition
- Low libido and sexual drive
- Low HRV
- Increased blood pressure
- High resting heart rate
- Elevated morning blood glucose
Tipping the scale
In order to restore balance we can do two things:
- Increase recovery
- Decrease stress
Although there are probably tons of things the average person could do to improve their recovery, I will focus on the things that have shown to have the biggest impact on the ANS and HRV.
- Improve aerobic fitness: action number one is to improve the body’s ability to recover. How does this work? The aerobic system is the primary system aiding recovery at rest. By improving the aerobic systems ability to produce energy the body is able to recover faster, this also makes the body more resilient to stress. Furthermore aerobic training causes vasodilation(widening) of blood vessels which decreases heart rate and it has also shown to have a positive effect on HRV.
- Sleep: One night of poor sleep will probably not affect your HRV that much, it’s when sleep debt accumulates over a period of time problems arise. Essentially, we want to focus on sleep quantity but also sleep quality. Waking up at night and waking up early have been shown to be early signs of depression and burnout. More on this here: Robert Sapolsky – Biology of depression
- Breathing: The way we breathe is highly correlated with the state of our ANS. High (chest) breathing indicates a fight or flight state, low (belly) breathing a more relaxed state. When we know this we can pay attention to when our body is shifting towards a more stressed state and we can implement some breathing techniques to bring it back down. So the next time you feel tightness in your traps, neck etc.
Try some of the following:
– High / low breath
– PRI 90 / 90 breathing
– Diaphragmatic breathing
To effectively manage stress, it’s essential to streamline your approach due to the multitude of options available. Here, I’ll provide high-impact strategies that yield maximum benefits with minimal effort.
- Mindful Meditation: Just 10 minutes of mindfulness meditation can lower cortisol levels by over 20%, aiding your perception to stress.
- Strategic Training: While exercise helps, intense movements like heavy squats or deadlifts stress the nervous system. Consider shifting focus to structural or higher-rep exercises for a period.
- Stop eating crap: Eliminate junk and highly processed foods, which contain inflammatory agents that can lead to intestinal permeability. This, in turn, triggers immune responses and inflammation.
- Engage in Hobbies: Pursue enjoyable activities without excessive alcohol consumption. Hobbies, especially with like-minded individuals, significantly reduce stress levels and enhance stress management skills.
- Body Fat Reduction: Your fat cells actually act as an organ itself in the body, which means they send out hormones like leptin, but also pro-inflammatory chemicals which cause systemic inflammation.Inflamed fat cells feel rock hard and can also hurt when you grab them. Yes I’m talking about your love handles..!
- Ashwagandha: This adaptogenic Chinese herb normalizes cortisol output, aiding stress regulation during challenging phases. It’s a valuable temporary aid, not a permanent solution.
*Note: These strategies primarily target physiological stress management and should be coupled with psychological support for optimal results.*
Stress is an accumulation of psychological and physiological stressors. We can measure the current state of the body using subjective and objective markers such as HRV, HR, BP and blood glucose. By looking at trends of these measurements we can actively start implementing protocols to improve recovery and decrease stress levels.