In recent years, there has been an increase in research and practical applications concerning the use of biofeedback training for athletic performance enhancement. It is important to be aware that the terms biofeedback and biofeedback training are not identical, and therefore need to be defined separately. Biofeedback (BFB) is the output from an electronic device with sensors and electrodes, which allows immediate and objective measurements of personal biological functions. This information is monitored on a computer screen and is transformed into auditory and visual signals, helping in learning to regulate body–mind activity in line with a basic psychophysiological principle. The main idea of this principle is that for every physiological change there is a parallel change in an emotional or mental component of human behavior, and vice versa. Biofeedback training (BFBT) is a process of learning psychophysiological self-regulation skills using information from a feedback device. Possible models of BFBT are as follows:
- One-to-one model: Sport psychologist or consultant and athlete work together throughout the sessions.
- Group model: Sport psychologist or consultant and several athletes with BFB equipment for each athlete work in one laboratory.
- Home practice: Athlete trains with portable BFB equipment at home, following sport psychologist or consultant’s written instructions.
Biofeedback modalities refer to the types of physiological indicators used for feedback during BFBT:
- Cardiovascular or heart rate (HR) feedback measures heart activity using beats per minute (bpm) by electrocardiography. In addition, practitioners use measurements of interbeat interval (IBI), the time between heart beat and msec-heart rate variability (HRV). HR generally increases with an increase in stress, and vice versa.
- Muscle or surface electromyographic feedback measures muscle activity in microvolts (µV). In cases of an increase in stress, electromyography (EMG) usually increases, as does muscle tension, and vice versa.
- Temperature or thermal (T) feedback is a measurement of skin temperature as an indication of peripheral blood flow. Temperature feedback is measured in Fahrenheit (F) or Celsius (C) degrees. During an increase in stress, skin temperature decreases, and vice versa.
- Blood pressure (BP) feedback is the measurement of the force exerted by circulating blood on the walls of blood vessels. BP is measured in terms of the systolic pressure over diastolic pressure (mmHg), and it usually increases with increases in stress.
- Electrodermal activity (EDA) feedback is a measurement of changes in the electrical activity of the skin surface. It can be measured by skin resistance (historically known as galvanic skin response [GSR], units of kohms, kΩ), by skin conductance (SC, units of microsiemens, µS), and by skin potential (SP, units of millivolts, mV). SC is the preferred method in psychophysiology research. SC increases with higher arousal, and vice versa.
- Respiration (R) feedback is a measurement of the respiration rate, which is the number of breaths taken within a set amount of time (breaths per minute). Respiration rate can be recorded using a tensometric sensor inserted into a cuff that is fixed around the individual’s chest. R increases with increased stress, and vice versa.
- Electroencephalograph (EEG) feedback, more recently known as neurofeedback (NFB), is a measurement of brain wave activity. EEG frequency groups are: Delta (1–4 Hz), Theta (4–7 Hz), Alpha (8–12 Hz), Beta (13–36 Hz), and Gamma (36–44 Hz). The response range under stress increases from sleep states (Theta waves) to excitement (Beta waves).
Research and Applications
Biofeedback research and applications can be dated back to the 1960s, when the focus was on the medical and clinical field. The primary modalities used in research in health care and cases of trauma and injury were EMG, EEG, and HR, especially in the laboratory setting.
The main goals of the BFB studies in this period were to demonstrate self-regulation skills and symptom reduction. Moreover, researchers attempted to describe an optimal model of BFBT and its applications in clinical practice. Later, in 1975, Leonard Zaichkowsky, the pioneer of biofeedback application in sport, described the positive effect biofeedback had on athletic performance. Research on BFB (usually EMG) efficiency in sport focused on reducing anxiety, increasing muscle strength, and decreasing muscle fatigue and pain in different kinds of sports. The EEG BFB (neurofeedback) studies focused on psychomotor efficiency and skilled motor performance; for example, enhanced performance in golf, shooting, and archery was shown to be associated with an increase in alpha (decreased cortical activation) activity in the left hemisphere. An additional trend in research and application of BFBT in sport was to include BFBT as part of a larger package of psychological interventions. A major limitation of this period was the inability to transfer the results from sterile laboratory conditions to a field setting and integrating BFBT into the training process.
The Wingate Five-Step Approach (W5SA) was developed to overcome this limitation.
The Wingate Five-Step Approach (W5SA)
The W5SA consists of five steps and a self-regulation test (SRT). Three of the steps are provided in a laboratory setting and the last two under field and training conditions. The steps are as follows:
- Introduction: The main goal is to teach the athlete basic self-regulation techniques, such as relaxation, imagery, self-talk, and concentration. At the end of this step, EMG, HR, and GSR BFB are used as part of the athlete’s mental training, especially the use of auditory or visual signals. The duration of this step can last up to 10 to 15 sessions, while each session can last approximately 45 to 50 minutes.
- Identification: In this step, most of the work that is done focuses on identifying and strengthening the most suitable biofeedback modality. Different sports require different biofeedback modalities. For example, in combat sports, EMG and GSR BFB are the most efficient modalities for measuring and practice. In contrast, EEG and HR are more suitable for sports such as golf, archery, and shooting. Additionally in this step, personal characteristics and the specific demands of the sport discipline should be taken into account. The duration of this step is approximately 15 sessions, each lasting 45 to 50 minutes.
- Simulation: The main goal of this step is to practice self-regulation and concentration skills in the laboratory setting using BFB in the natural environment, such as watching video scenes under competitive situations. In addition, the basic self regulation techniques are modified according to the sport’s demands. In this step relaxation is shorter, imagery is set according to competition length, and self-talk is specific to the competitive situation. This step lasts about 15 sessions, each of them approximately 50 to 60 minutes.
- Transformation: The athlete mentally prepares for the upcoming competition. All the skills that the athlete learned and rehearsed in the laboratory are transferred and integrated into the actual training setting by using a portable BFB device. This process allows the athlete to be prepared for future competitions by acquiring self-regulation abilities and mental readiness. This step lasts about 15 sessions and is provided during different parts of the training.
- Realization: In this step, BFB is used in different settings, such as the field, pool, gym, bus, and boat at sea. In addition, the BFB is accompanied with relaxation, concentration, and imagery, which are used in different parts of the competition, such as before the start, between combats, after warm-up, and at the end of competition. The process of this step begins by applying the skills during less significant competitions, and gradually requesting the athlete to apply the skills in more significant events.
Self-regulation test (SRT) is given to the athlete before the beginning of the program and before each step. The goal is to examine the self-regulation level of the athlete. Recently, practitioners have been integrating the W5SA with the athlete’s physical training, incorporating it within the periodization concept.
Neurofeedback (NFB) or EEG BFB relates to changes in electrocortical activity of the brain as the physiological measure of emotional and cognitive processes. The historical development of NFB began in clinical settings using alpha-type training. Later, research focusing on performance enhancement using neurofeedback of alpha activity in the left hemisphere, which is usually associated with expertise. Moreover, some research suggested that alpha range can be used as an indicator of attention processing. In sport, NFB is applied for the purpose of optimizing athletic performance by the athlete being able to master self-control and self-regulation strategies. For example, the first NFB study in sport examined the left–right hemispheric activity in rifle marksmanship. Neurofeedback training in sport is used in models for decreasing arousal or increased relaxation skills (alpha–theta type training) and for increasing attention–performance relationships (theta–beta type training).
BFB in Exercise Psychology
The major goal of using BFB in exercise psychology is to understand exercise behavior and the mechanisms that have an effect on participation rate and exercise adherence. In line with this goal, research has focused on the effect of self-monitoring and self-regulation of exercise intensity
for fitness enjoyment, as well as adherence rate. Results have indicated that the positive effects of BFBT on achieving optimal exercise intensity for health and well-being can be accomplished during a relatively short time period.
Professional BFB Organizations, Journals, and Equipment
There are four major international BFB organizations that provide annual meetings, workshops, and publications: (1) The Association for Applied Psychophysiology and Biofeedback (AAPB) in North America (www.aapb.org); (2) The Biofeedback Foundation of Europe (BFE; www.bfe.org); (3) The International Society for Neurofeedback and Research (ISNR; www.isnr.org); and (4) The Biofeedback Certification International Alliance (BCIA; www.bcia.org), which provides biofeedback certification according to the Professional Standards and Ethical Principles.
There are two major scholarly journals: (1) Applied Psychophysiology and Biofeedback (APB), formerly known as Biofeedback and Self-Regulation, and (2) Biofeedback. Both are supported by the AAPB.
There is a variety of biofeedback equipment that can be used in laboratory and field settings, depending on the intervention goal. Advanced technology and awareness of the possibilities of BFBT have led to the innovative and improvement of BFB electrodes, noncontact monitor tools, telemetric systems, and computer programs.
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