A Foray Into Biofeedback

By Judy Finerghty, Head Coach, Vassar College  @VassarWLax

It seems everywhere we look, there is a new app, watch or gadget designed to track fitness, heart rate, location, calories, sleep, and even mood. At the same time, we coaches are also vigilant in preaching to our players the importance of getting adequate sleep, good nutrition and managing stress in order to optimize performance, avoid illness and to prevent and recover from injuries. Despite our efforts and the imposing amount of evidence supporting the need for rest and recovery, our student-athletes still push their limits. Compounding this, there is an unspoken ‘competitive hypervigilance’ that exists on many college campuses, whereby students attribute a sense of valor to functioning on little sleep; hammering out long academic papers, readings and projects while also managing other organizational commitments. We’ve all heard students talk about not sleeping because they had to write a 15-page paper and study for an exam on the same night, only to be one-upped by another that had a 20-page paper and two exams the next day. Certainly, this brand of competitiveness is not ideal.

      Photo courtesy of Vassar Athletics.

Generally speaking, we determine what kind of mental, physical or emotional state our players are in simply by recognizing signs of fatigue or from talking with and observing them. Sometimes those signs are less visible, and the cumulative effects of physical training, lack of sleep and chronic stress can result in injury, sickness or poor performance.

In looking for a way to both quantify the deleterious effects of fatigue and chronic stress and also to encourage athletes to become more intentional about taking better care of their bodies, we turned to the Heart Rate Variability (HRV) metric that provides accurate and useful biofeedback. HRV differs from heart rate in that it furnishes information about a greater range of physiological responses than heart rate alone. HRV is the only non-invasive means of measuring vagus nerve function which moderates the Autonomic Nervous System (ANS) signaling changes in physiology including inflammatory response, stress levels and recovery.

Functions such as heart rate, blood pressure, body temperature, digestion, electrolyte balance, pupillary response, and others are regulated by the ANS. Comprised of two branches, the ANS sympathetic division (which controls one’s fight or flight response – when being chased by an assailant for example) is necessary for short-term survival, and the parasympathetic (which influences rest, recovery and digestion), is needed for long term survival. Sympathetic pathways are also invoked during exercise, fatigue, episodes of challenging mental work, or even during arguments. Long term incitement of sympathetic activation results in chronic stress loads that exceed amounts that can be mitigated by the parasympathetic system. HRV measures quantify the overall health of the ANS and show how well the parasympathetic complex is countering and coping with sympathetic stimulation.

Specifically, HRV measures the interval between the R waves in a heartbeat. One may think logically that a regular and consistent time interval between those wave points would indicate a healthy person. But the opposite is actually true. The R intervals vary in milliseconds reflecting the microchanges of the push and pull mechanisms as the sympathetic and parasympathetic pathways respond to shifting stimuli. Therefore, a high variability indicates a healthy system, and low variability reveals a weakened system.

HRV can be measured in several ways ranging from electrocardiograms (EKG) to wearable devices such as chest straps, finger sensors and watches. Those devices however can be costly or inconvenient to use. There are also apps that enable users to measure their HRV through a cell phone camera. We chose this method because the results still have a high degree of accuracy and don’t require a purchase other than the cost of the app (there are some free apps available as well, but those typically necessitate a fee-based subscription after the trial period). Measurements are read by the app when the user taps the start button and places a finger over the camera, holding still for two minutes. Consistency is the key for obtaining the best results so readings should be taken at about the same time every day and in the same body position (lying in bed when one first wakes up is an ideal time to do this). The app takes about 10 days to two weeks to obtain a baseline measure for each individual. After that the app reveals daily HRV and readiness scores. Upward or downward movement in scores over a few days or longer reveal trends in homeostasis, but single significant and precipitating events that occur on one day can also be valuable (for example an especially bad night of sleep). HRV baseline scores vary between individuals based on factors like age, fitness level, and sex, so it is important to evaluate a person relative to their own baseline, although population norms are also available.

So, what’s the real point and does it even work? Again, primary goals for this venture were to assess and track each player’s overall health, well-being and recovery, and to offer tangible feedback that inspires them to become more mindful and deliberate about taking better care of themselves. The app we use is HRV4training.com. There are several other apps including Apple Health, EliteHRV, SweetwaterHRV, and Welltory among others. HRV4training was selected because it can be used on both Android and iPhones, and it also has a Coach’s Dashboard that provides a snapshot of the entire roster’s HRV and Daily Readiness scores (indicating improving or declining trends in their physiology). This gives clues as to how the team’s recovery is trending and assists in making decisions about the intensity of conditioning during practice. I found the dashboard helpful for getting this quick look at the team’s state of being, as well as for looking more closely at individual player’s data over the course of the season. The information also alerted me to check in with those individuals that showed an acute downward spike in HRV or a declining trend, and most of the time the cause was academic stress, injury or illness. I also tracked my own HRV from February through July last spring as well and was not shocked to see that scores trended upward just after the season ended!

Admittedly, some of the athletes were more consistent about taking HRV readings than others. But most reported that using the app influenced them to try and improve their numbers by managing time, getting more sleep, eating healthier, or using relaxation strategies like meditation or yoga. There is so much more to learn about the information provided via HRV readings, but for now, anything that can be done to heighten awareness and develop habits that promote physical and emotional health will assuredly lead to improved performance on the field as well.

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