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Finding the Balance

The brain is the dominant organ, and is in control of maintaining our internal environment: homeostasis. It responds to changes from stimuli, both internally and externally. Our nervous system transmits responses and is comprised of our Central and Peripheral systems. Within the Peripheral system, there are subdivisions including the parasympathetic, or 'rest and digest' and sympathetic or 'fight and flight' responses. These systems are complementary, so when one is active, the other is suppressed.

Detecting Stress

When the brain detects a perceived threat from the environment, the sympathetic response becomes elevated, resulting in a stress response such as increased breathing rate, increased heart rate and increasing blood glucose output in preparation for the 'fight-or-flight' response. This is a beneficial process to ensure survival. Over time, the brain can become sensitised to stress signals and the response becomes habituated, or to an extent, learned. This can come through exposure and practice, so we don't get overloaded by the same stimulus. However, a dysregulation of the sympathetic system is associated with increased risk of poor hormonal, metabolic and cardiovascular health (Mastorakos et al., 2005). Moderating and keeping the two systems in balance, so we are not always in 'fight-or-flight' mode, is a key skill to develop for health and performance. Regular physical activity of the right kind, and cognitive behavioral techniques like mindfulness and meditation can help keep these systems in balance (Mc Wewen, B.S., 2017).


There are many signals in our environment that can contribute to the sympathetic response, such as email notifications, sleep disturbances, drug and alcohol abuse, and overall work-life balance. Stress is cumulative, so if there is a lot going on, that one extra stress might be too much to handle. It is difficult. Particularly if we have disrupted sleep, this can impair the balance and over time, contribute to impaired glucose tolerance, systemic inflammation and increase chronic disease risk.

Training: Needing, Wanting, or Feeling?

Needing to train is very different from wanting to train, which again is different from feeling like training. Add poor sympathetic regulation to the stress of 'needing' to train, especially to a performance metric in competitive session or group, added anxiety and stress to each session will keep the systems out of balance, and substantially increase risk of injury. This could be further compounded by an external or internal pressure to 'perform better' in the next session.


Attempting to destress via an exercise that activates the 'fight or flight' response, such as High-Intensity Interval Training, can cause further stress, elevate blood glucose particularly if untrained, and cause hormonal dysfunction. Even in recreationally active individuals 'over reaching', in as little as three weeks, increases in muscle sympathetic activity decreased performance (Coates et al., 2018).

So What?

Across a competitive season, or in life, ignoring the underlying condition of the body is a recipe for poor health and performance in the long term. Stress is cumulative, and by practicing regulating the parasympathetic and sympathetic systems, through techniques such as breathing, and mindset, low-intensity exercise, can help to reduce overall stress, improve blood flow, focus the mind and improve performance in the long term.

Go slow, especially if you're untrained, for better parasympathetic regulation.

Take home: Track Heart Rate Variance (HRV) over time to monitor the balance of the parasympathetic and sympathetic systems. Salivary Cortisol Tests have recently been developed to easily check stress hormones. Know when you're in balance, and when you're not. Training when you are out of balance will reduce health and performance.

Listen to the body, train by feel, and have fun!


  1. Coates, A., INCOGNITO, A., SEED, J., DOHERTY, C., MILLAR, P. and BURR, J., 2021. Three Weeks of Overload Training Increases Resting Muscle Sympathetic Activity.

  2. G, M., M, P., E, D. and GP, C., 2021. Exercise and the stress system. [online] PubMed. Available at: <> [Accessed 3 May 2021].

  3. McEwen, B., Nasca, C. and Gray, J., 2021. Stress Effects on Neuronal Structure: Hippocampus, Amygdala, and Prefrontal Cortex.

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