Broadly speaking, stress is experienced in two forms: physical and psychological. And to even things out, the body reacts in two different ways: through the sympathetic nervous system and the parasympathetic nervous system.

Fight Or Flight

Whether it’s physical stress such as pain, injury, or illness, or psychological stress like from a troubled relationship, financial strain, or experiencing a traumatic event, our sympathetic nervous system kicks in to heighten our body’s ability to cope. The resulting release of hormones increases the heart rate, so we’re ready to either stay and FIGHT the stress, or turn and FLY from it.

As well as increased blood flow, the body also experiences an enhanced immune response, which is where the idea that stress inside appropriate time frames is actually good for our immune system.

Rest And Digest

On the other hand, our parasympathetic nervous system serves to calm us down. Among other functions, it regulates the heart rate, blood pressure, digestion, and immune response, to slow things down and help us relax. After a bout of acute stress, it tips the scale back the other way, and it’s this state which allows for productive sleep.

Exercise as the Stressor

A rise in blood pressure, heart rate, and respiratory rate are healthy sympathetic responses to exercise to help us get the job done, but they retreat when we don’t need them anymore. Repeated regularly, this will result in adaptations to our physiological responses – exercise therefor trains our stress response.

CrossFit is designed with this in mind. Good programming takes all of this into account featuring workouts that challenge different energy systems in multiple modalities with rest days built in. We can’t go all out all the time!