Over-training is a form of burnout experienced in athletes resulting in unexplained performance drops and sensations of above-normal fatigue for the same workload. This phenomena has been well-documented.

But it’s not just a physical thing. A training overload can induce “cognitive control” fatigue in the forefront of the brain, which is associated with reduced “prefrontal cortex” activity and the feeling of a “tired brain”.

This in turn is associated with acting impulsively (opting for immediate rewards instead of bigger ones that would take longer to achieve) and impaired decision-making.

So while endurance exercise is generally good for your health, overdoing it can have adverse effects on your brain’s mental ability to perform optimally (as well as a tired aching physical body).

Excessive Intellectual Work Also Leads To Burnout

“The lateral prefrontal region affected by sport-training overload is exactly the same that is vulnerable to excessive cognitive work”

Both excessive intellectual work and physical training induce a similar “cognitive fatigue”, because both require “cognitive control” and both exert a similar effect on the same part of the brain.

So the second key message here is: Neural states matter: you don’t make the same decisions when your brain is fatigued. It’s important to monitor your fatigue levels in order to prevent bad or poor decisions being made – across all domains of your life.

So there you have it. Both Mental and Physical Effort can overload your brain and affect the quality of your day-to-day decisions. This reinforces the importance of recharging and recovering fully (physically and mentally) before making an important decision.

Source: Neuro-computational Impact of Physical Training Overload on Economic Decision-Making