Let the Nervous System Help Choose the Exercise

Exercise selection is often based on what we want the body to do: strengthen a muscle, improve mobility, increase power, or develop endurance. But there is another question worth asking before choosing an exercise: How does the nervous system interpret the stimulus? The autonomic nervous system (ANS) is constantly responding to sensory information from the environment and from within the body. Its responses can provide valuable insight into whether a particular exercise is being perceived as an appropriate challenge—or as a threat. Check out my Zelos Podcast conversation with Dr. Joel Kerr as we further discuss this topic.

The central nervous system has a fundamental objective: survival. From a very basic perspective, the body is continually managing two primal threats. The first is starvation—the inability to obtain or conserve the energy necessary to survive. The second is being attacked or eaten by a predator. Although modern humans rarely face either threat in its original form, the nervous system still uses many of the same protective strategies. Physical pain, instability, unfamiliar movement, excessive fatigue, loss of balance, or an inability to control a position can all be interpreted as potential threats. The response may be to increase muscular tension, restrict movement, alter breathing, change balance strategies, or simply avoid the movement.

This gives us another way to look at exercise intensity. Rather than determining intensity solely by load, repetitions, heart rate, or perceived exertion, we can observe the autonomic response to the exercise itself. Changes in breathing, heart rate, balance, range of motion, peripheral vision, coordination, and general movement quality can provide clues about how the CNS is processing the input. If a relatively simple exercise produces a disproportionate change in these variables, the stimulus may be exceeding the individual’s current capacity for that movement. Conversely, if the response remains stable and organized, we may have found an appropriate level of challenge.

The practical application is to use the ANS as a kind of barometer for exercise selection and dosage. Establish a simple baseline—perhaps balance, range of motion, breathing, or peripheral vision—then introduce a movement and observe what changes. If the response improves or remains organized, the exercise may be appropriate to progress. If the response deteriorates significantly, rather than assuming the person simply needs to “work harder,” consider changing the position, reducing the load, altering the range of motion, changing the speed, or selecting a different exercise altogether. The goal is not to eliminate stress; it is to provide a stimulus that the nervous system can successfully interpret and adapt to.

Ultimately, effective training is less about forcing the body to perform a predetermined exercise and more about providing the nervous system with an appropriate problem to solve. When we learn to observe autonomic responses, exercise selection becomes more responsive and individualized. Instead of asking only, “What exercise should I do?” we can begin asking a more important question: “What is the nervous system telling me about what this person is ready to do?”