Biofeedback is a term that describes two distinct sports science concepts. Biofeedback is a methodology used to obtain data relating to various aspects of bodily function in athletic performance. Biofeedback is also a training and coaching method.

As a methodology, biofeedback is a monitoring process by which different kinds of equipment are used to obtain information concerning a number of different functions controlled by the autonomic nervous system. Biofeedback data will commonly include heart rate, blood pressure, respiration, and other quantifiable features of human performance.

Biofeedback also describes the ongoing relationship between the physical performance of the human body in conjunction with the thinking and the emotional processes of the subject. In this sense, biofeedback is a training and coaching method, one that is designed to alter the behavior of the subject; biofeedback is intended to permit an athlete to acquire a skill that may be used to best manage the relationship between physical and mental performance.

In the data-gathering sense, biofeedback utilizes a number of different tools. The most common of these devices is a heart monitor, which collects data with respect to heart rate and physical performance. Heart monitors are portable devices that do not interfere in the performance of an athlete to any significant degree. Sophisticated biofeedback technologies include the measurement of heart rate, blood pressure, oxygen uptake (VO2max, an expression as to how much oxygen can be processed by the body at different stages of exertion), and the perspiration rate (an indicator of how efficiently the thermoregulatory system functions under variable stresses). In addition to these factors, an electroencephalograph (EEG) may be employed to monitor the brain wave activity, coupled with an electromyography (EMG), which measures the amount of tension and electrical activity in the muscles at different times, when subjected to varying stresses.

The data obtained through these biofeedback measurements may be readily compared with the results of other physical tests of autonomic function, such as the analysis of urine and blood.

One of the prominent biofeedback applications employed by athletes is relaxation techniques. The ability of an athlete to relax in the stressful circumstances of competition is an important component of the overall emotional control required of the athlete in competition. The development of a relaxation strategy for the individual athlete begins with the biofeedback testing to provide the physical data concerning the function of the autonomic nervous system of the athlete. The data must be gathered in a fashion that simulates the athlete's actual competitive performance. Once obtained, the information can be plotted in comparison to actual progress made by the athlete from the start to the finish of the simulated competition. The scientist or trainer conducting the testing then evaluates the results in conjunction with the athlete. The athlete must provide their subjective input concerning the various parts of their performance. The question for the athlete is "How did I feel at each segment of the competition? How do my subjective feelings about my performance compare with the measured heart rate, perspiration rate and other data?". This process permits the athlete and the trainer to compare the objective data gathered through testing of the athlete's autonomic function with the athlete's subjective assessment of his or her performance.

By comparing objective biofeedback data with subjective athletic impression, the athlete can develop strategies to combat any competitive areas where they feel increased stress or nervousness. As an example, biofeedback techniques can be employed to assist a long jumper who repeatedly commits a foot fault (where the jumper's foot goes past the end of the jump board, rendering the jump illegal). A trainer, with the athlete performing a simulation of the event, will use the biofeedback data to identify the precise moment of excess tension in the athlete's body during the jump sequence to assist the athlete in developing a strategy to maintain a consistent emotional level throughout the jump. The moments of excess tension will be likely be apparent in the testing through indicators such as increased heart rate and breathing function, among other data gathered. To settle this athlete, a number of relaxation techniques may be employed, including deep breathing techniques and the use of positive mental images by the athlete as an aid to concentration. Breathing exercises are intended to relax the jumper before the approach by the athlete to the runway leading to the jump. Quick and irregular breathing patterns are evidence of stress and the corresponding invocation of the body's "flight or fight" response, which also signifies an elevation in levels of the hormone adrenaline. An overly stimulated long jumper is much more likely to fault than a jumper who is calm and composed.

The rhythm of regular breathing is designed to settle the athlete; imagery techniques such as directing the athlete's attention to the sensation of the air on the jumper's body as a successful jump is performed, or the sensation of the sand in the landing pit on the jumper's entry, create a sense of focus and concentration for the athlete on the event at hand.

Biofeedback can also be used to assist an athlete in the planning of future training sessions. The determination of an athletes maximum heart rate, a target against which individual workout intensity can be planned. At moderate training levels, the desired heart rate might be 65% of the athlete's maximum rate; in more intense workouts, the athlete might seek to achieve a heart rate at 90% or more of the maximum.

In warm weather environments, urine and perspiration samples can be tested to determine whether the athlete's diet has sufficient sodium or other electrolytes commonly lost through the body's fluid elimination. This biofeedback data assists both the athlete and coaches to develop an appropriate hydration strategy, to ensure that the athlete's fluid and electrolyte intake remains sufficient both before, during, and after all training and competitive sessions.

There is a powerful interrelationship between biofeedback techniques and the concept of visualization. Visualization is a technique that is intended to reduce stress, to enhance relaxation, and to sustain focus by directing the attention of the athlete to a specific aspect of the athlete's routine or performance. In this fashion, biofeedback can assist the athlete in developing mental cues to help eliminate distractions such as crowd noise or movements.

Auditory (hearing) clues can also be employed as the trigger to induce the athlete to maintain the desired level of autonomic function. The type of clue that will function best for a particular athlete will be tailored to the athlete, as a result of the biofeedback process; there are no set rules as to which type of clue is likely to work best. In shooting sports, athletes seek to reduce their heart rate through deep breathing and other relaxation methods, as they are in their most physically stable position to deliver a shot when their body is between heartbeats. The more efficiently the shooter can breathe and reduce the heart rate, the quicker the shots can be fired.

In some sports, biofeedback can be incorporated with the use of physical simulators to assist the athlete. Bobsledders are among the athletes who use a computer controlled simulator to precisely replicate the sensations that they experience on particular bobsled courses; the biofeedback data such as heart rate and its relationship to the effect of the gravitational forces experienced by the bobsledders is gathered as the simulation proceeds. When the bobsledder knows that a difficult corner or other physical element of the course lies ahead, he can anticipate that he will become more anxious or tense and prepare himself accordingly.

The successful use of biofeedback data is dependent upon both the quality of the physiological testing of the athlete, combined with motivation of the athlete to use the biofeedback process effectively. The gathering of data alone will not provide a remedy to deficiencies in athletic performance.

SEE ALSO Eccrine sweat secretion; Heart rate monitors; Heart rate: Target heart rate; Metabolic response; Visualization in sport.