(This post was originally written by me for Austin Fit Magazine www.AustinFitMagazine.com)

Organisms must adapt to environmental and physical demands to ensure their survival, and the athlete organism is no different. Adaptability and physiological variability ensures an athlete’s success in competition, in training, and in recovery. Humans are hardwired to be able to react to stressors, as well as quiet their system when there are few demands and rest is needed.

Problems occur when athletes can neither react to new stimuli and demands nor shut down when recovery is needed. We’ve all had bad training days where something just seems “off.” Either there isn’t the energy to perform or we’re over-stimulated, reaching physiological barriers early in the workout and at much lower levels of stimuli. As a physical therapist, I am constantly trying to get in touch with the state of my patients’ nervous system so that I can apply the most appropriate therapeutic intervention for their given level of sensitivity. I recognize that their objective (and subjective) presentation is a mere reflection of their holistic ability to switch on or switch off.

The autonomic nervous system (ANS) is a major player in unconscious, automatic functions of the human body, such as respiratory and heart rate, digestion, and blood pressure. This is opposed to the voluntary aspect of the nervous system–the somatic nervous system—that controls movement and sensation, or the wiring behind skeletal muscle activity.

Human performance is dependent on a healthy functioning neuromuscular system to perform complex movements, to move heavy loads, or to persist when the legs are burning. Tasks like these are primarily controlled by the somatic system (which, from an evolutionary perspective, is the more modern part of the nervous system). When presented with a challenge, the brain processes the variables and instructs the muscles to perform a task. We sense; then, we react. On a basic level, this is how the somatic nervous system works.

But on a deeper and more primitive level, the ANS is busy fine-tuning things. Due to its wide range of physiological effects, the ANS can be considered the gauge and control center for how the body reacts to those things that we really shouldn’t have to think about. Again, we sense and we react. But in this case, we may not even be aware of the bodily changes taking place, such as changes in heart rate, blood pressure, perspiration, or arousal level. It also applies to more complex changes in muscle tone, the secretion of sugar and other metabolites for use by our tissues, respiratory rate and pattern, and the release rate of stress hormones into the bloodstream.

Athletes with an adequately functioning autonomic nervous system are easily capable of preparing for competition and performing at an appropriate energy level. They can also return to a restful, quiet state when it’s time to recover. In other words, they can turn on when it’s “go time” and they can turn off when it’s not. This ability is vital to sustaining a regimented workout program, especially one that is structured and timed for a specific event. Understanding athletes’ biological readiness is key in applying appropriate workouts that will avoid the pitfalls of overtraining, poor adaptation to training, and, ultimately, injuries or burnout.

The ANS has two subdivisions, sympathetic and parasympathetic. The sympathetic nervous system (SNS) is responsible for “fight or flight.” It can be thought of as the part of the ANS that reacts to stress and stimulates physiological systems that prepare us for action. The parasympathetic nervous system (PNS) is responsible for control of activities when we are at rest (“rest and digest,” or “feed and breed”). Sympathetic and parasympathetic divisions can at once be thought of as opposite and complementary of one another. While the SNS quickly reacts to immediate stressors, the PNS looms in the background, constantly fine-tuning the body to maintain homeostasis, or system neutrality, finally taking over when there is no longer significant stress.

It is desirable for athletes’ SNS to drive them during competition and intense workouts. Remember: the ANS has a direct effect on important physiological systems, such as heart rate, breathing rate, and the mobilization of sugar and other metabolites used by muscles. It is the SNS that ramps up these variables to prepare us for and sustain us during athletic endeavors. However, all too often the SNS becomes over stimulated due to chronic stress or a poorly timed training regimen. The nervous system may get bombarded to the point that it is no longer able to switch off. We begin to get rigid—our physiology becomes less able to adapt to new stressors in a variable way and the body tenses up, causing the PNS to be suppressed.

There are methods to measure athletes’ physiological readiness as well as their neuromuscular adaptability. Austin coaches Aaron Davis and Ben House of Train. Adapt. Evolve. use the Omegawave system to measure their athlete’s readiness for upcoming training sessions. Through electrocardiogram analysis, factors such as fatigue and stress levels can be measured, allowing Davis and House to dose workouts through objective as well as subjective data. To a large degree, the Omegawave is quantifiably measuring the state of the autonomic nervous system. The volume, intensity, and type of workout or practice can then be fine-tuned and structured based on this personalized information.

Davis and House explain that, “as strength and conditioning coaches, we are dealers of stress, and we can only give you what your body can handle.” Omegawave (which is now being used by a variety of professional sports franchises) allows them to get a peek inside their athletes’ ANS, their potential physiological limitations, and their readiness for that day’s workout. This is an important factor in ensuring that the proper load and intensity can be applied in a manner that allows athletes to avoid nervous system rigidity and a musculoskeletal system that is unable to adapt. Without respect for how the autonomic nervous system functions, full athletic potential may not be reached, risk of injury is elevated, and burnout is inevitable.