CT Scan of lung in COVID - pulmonary rehab exercises

Biofeedback for Pulmonary Rehab-COVID 19

As the world continues to grapple with the effects of COVID-19, the importance of pulmonary rehabilitation has come to the forefront. Pulmonary rehab is essential for patients recovering from the virus, as it helps restore lung function and improve overall health. Incorporating targeted breathing exercises for the lungs can significantly enhance this rehabilitation process, promoting better oxygenation and respiratory efficiency. Additionally, utilizing a breathing exercise device for lungs can further aid recovery by providing structured support for lung function improvement. Many individuals can benefit from pulmonary rehab exercises at home, allowing them to engage in effective recovery routines in a comfortable environment. This article explores the role of breathing and HRV biofeedback in optimizing pulmonary rehabilitation after COVID-19, highlighting how these techniques can support patients on their journey to recovery.

COVID-19 ASSOCIATED PNEUMONIA

SARS-CoV-2, the virus that causes COVID-19, is part of the coronavirus family.

When the virus gets in your body, it comes into contact with the mucous membranes that line your nose, mouth, and eyes. The virus enters a healthy cell and uses the cell to make new virus parts. It multiplies, and the new viruses infect nearby cells.

Think of your respiratory tract as an upside-down tree. The trunk is your trachea or windpipe. It splits into smaller and smaller branches in your lungs. At the end of each branch are tiny air sacs called alveoli. This is where oxygen goes into your blood, and carbon dioxide comes out.

As the infection travels the respiratory tract, the immune system fights back. The lungs and airways swell and become inflamed. This can start in the alveoli of one part of the lung and spread to the nearby alveoli of other parts.

In pneumonia, air sacs in the lungs fill with fluid, limiting their ability to take in oxygen and causing shortness of breath, cough, and other symptoms.

Doctors can see signs of respiratory inflammation on a chest X-ray or CT scan.

On a chest CT, they may see “ground-glass opacity” because it looks like the frosted glass on a shower door.

 (a) Axial thin-section non-contrast CT scan shows diffuse bilateral confluent and patchy ground-glass (solid arrows) and consolidative (dashed arrows) pulmonary opacities. (b) The disease in the right middle and lower lobes has a striking peripheral distribution (arrow). [Radiological Society of North America].

THE EFFECT OF COVID-19 IN SHORT-TERM AND LONG-TERM FOLLOW-UP

The effect of COVID-19 will vary significantly throughout the disease, with most people experiencing some of the following symptoms:

  • fever,
  • cough, sputum production, shortness of breath,
  • fatigue,
  • anorexia,
  • myalgia,
  • central nervous system manifestations (such as headaches, migraines, dizziness, and ataxia),
  • and peripheral nervous system manifestations (such as nerve pain, speech, vision, and taste problems).

While some of these symptoms may resolve naturally, some people may have impairments that persist, particularly following a prolonged hospital and ICU stay.

Doctors in Hong Kong (March 13, 2020) reported the findings of the first follow-up clinics of recovered Covid-19 patients. They suppose some recovered patients have lost between 20% and 30% of their previous lung function (South China Morning Post). The doctors report that lung scans of recovered patients also reveal substantial lung damage.

Researchers revealed that six weeks after hospital dischargemore than half of the patients had at least one persistent symptom, predominantly breathlessness and coughingCT scans still showed lung damage in 88% of patients. However, by the time 12 weeks after discharge, the symptoms had improved, and lung damage was reduced to 56% (COVID-19 Patients Suffer Long-Term Lung and Heart Damage – But They Can Recover With Time – By European Lung Foundation, September 7, 2020). There’s the initial injury to the lungs, followed by scarring. Over time, the tissue heals, but it can take three months to a year or more for a person’s lung function to return to pre-COVID-19 levels.

In the recovery period, people with COVID-19 may be expected to present with significant muscle wasting in both the locomotor and respiratory muscles. This may contribute to ongoing breathlessness and fatigue, reduced exercise capacity, poor balance, and loss of functional independence (Rehabilitation following COVID-19 in the pulmonary rehabilitation setting. JUNE 2020. Respiratory Network).

PULMONARY REHABILITATION PROGRAMS AFTER COVID-19

Changes in the anatomical and physiological properties of the chest’s tissues and organs caused by disease lead to decreased elasticity in the lungs and surrounding tissues. As a result, the energy cost of ventilation increases. The respiratory muscles must work harder to overcome both elastic and bronchial resistance, significantly raising their workload. This increased energy cost, combined with the depletion of respiratory muscles, contributes to shortness of breath and a sensation of air hunger. Together, these sensations form the complex experience commonly referred to as “shortness of breath.”

Many pulmonary diseases reduce the respiratory surface of the lungs and lead to ventilation disorders, such as restrictive syndrome. This decrease in lung volume occurs for two main reasons. First, hardening of the lung tissue contributes significantly. Second, restricted lung mobility also plays a crucial role. Together, these factors lead to a notable reduction in lung volume. Adhesions can form and prevent the lungs from expanding fully. When pleural inflammation also occurs, chest movement becomes intentionally limited, as severe pain restricts chest excursion.

Exercise therapy in pulmonology has several key tasks. First, it aims to achieve regression of reversible changes in the lungs. Second, it focuses on stabilizing irreversible changes. Additionally, exercise therapy promotes compensation and normalization of lung function.

  • General tonic effect: stimulation of metabolic processes, increase in neuropsychic tone, recovery, and increase of tolerance to physical activity, stimulation of immune processes;
  • Preventive effect: mastery of breathing control technique, an increase of the protective function of the respiratory tract, reduction of intoxication;
  • The pathogenic (therapeutic) effects include several essential improvements. First, exercise therapy enhances external respiration functions. Second, it corrects the mechanics of breathing. Additionally, it accelerates resorption during inflammatory processes and improves bronchial patency. Furthermore, it removes or reduces bronchospasm. Finally, it regulates external respiration functions and increases their reserves.

General Tonic and Special Breathing Exercises

In exercise therapy for respiratory issues, various techniques are applied to improve overall health and target specific respiratory functions.

First, general tonic exercises help enhance the function of all organs and systems, while moderate and high-intensity exercises specifically stimulate external respiration.

Low-intensity exercises, however, lack a training effect on the cardiovascular and respiratory systems.

Additionally, special breathing exercises strengthen the respiratory muscles, increase chest and diaphragm mobility, and reduce congestion. These exercises promote pleural stretching, ease sputum excretion, and enhance breathing coordination and movement.

Furthermore, breathing gymnastics techniques focus on correcting pathological breathing patterns, relaxing tense muscle groups, and improving respiratory muscle function.

Muscle Relaxation Techniques

Techniques such as autogenous training, post-isometric muscle relaxation, and physical exercises for associative and segmental muscles are helpful to support relaxation. Therapeutic massages, including myofascial release and segmental reflex massage, also address myofascial muscle changes. Exercises involving segmental and associative muscles are most effective for these issues. Moreover, incorporating weights like sandbags in breathing exercises strengthens the abdominal and intercostal muscles and increases diaphragm mobility.

Fundamental Lows of Breathing

Performing breathing exercises requires compliance with the fundamental laws of breathing:

  • before any physical activity, it is necessary to remove residual air from the lungs, for which it is necessary to exhale through the lips folded into a tube;
  • inhalation is mainly (80%) carried out by the diaphragm, while the muscles of the shoulder girdle should be relaxed;
  • the duration of the exhalation should be approximately 1.5-2 times longer than the inhalation;
  • Inhalation occurs when the chest is extended, and exhalation occurs when it is compressed (for example, when bending over).

Techniques for Exhalation and Breathing Rate Control

Exhalation is usually carried out by relaxing the muscles involved in inhalation under the influence of the chest’s gravity; delayed exhalation occurs with the dynamic inferior work of these muscles. The elastic forces of the lung tissue remove air from the lungs.

Forced exhalation happens when the muscles responsible for exhalation contract. You can strengthen exhalation by tilting the head forward, bringing the shoulders together, lowering the arms, flexing the trunk, and raising the legs forward. Additionally, breathing exercises allow you to adjust the breathing rate freely.

More frequently, exercises focus on voluntarily slowing down the respiratory rate. In this case, it is helpful to count silently to yourself. This practice reduces the speed of air movement and decreases resistance as air passes through the airways. Increased breathing frequency increases breathing speed. Consciously learning to regulate breathing starts with static exercises. Incorporate rhythmic static breathing exercises, as these help decrease respiratory movements by deepening them. At the same time, this practice strengthens the respiratory muscles and tones the intercostal muscles.

Enhanced Breathing Techniques and Muscle Strengthening

Breathing with additional resistance (inhalation through lips folded into a tube, through a tube, inflation of rubber toys) reduces the frequency. It increases the depth of breathing and activates the work of the respiratory muscles. Breathing through the nose is recommended because it moistens and purifies the inhaled air. Moreover, irritation of the receptors in the upper respiratory tract reflexively expands the bronchioles. As a result, this deepens breathing and increases blood oxygen saturation.

If necessary, to spare the affected lung, apply the initial positions that limit the chest’s mobility from the affected side (lying on the affected side).

Using weights such as sandbags when performing breathing exercises helps strengthen the abdominal and intercostal muscles and increases the mobility of the diaphragm.

To dose physical activity effectively, you can adjust several factors. First, change the initial position. Second, modify the pace and amplitude of the movements. Additionally, vary the degree of muscle tension, the number of exercises performed, and their duration. Finally, rest pauses and relaxation exercises should be incorporated to enhance the overall effect.

  • THE ONLY RMT DEVICE FEATURING INDEPENDENT INSPIRATORY/EXPIRATORY DIAL CONTROL.
    The Breather functions as both an inspiratory and expiratory muscle trainer, with adjustable dials for independent resistance settings for inhalation and exhalation. It is the ultimate device for respiratory care. Think of it as a lung trainer, supporting respiratory health and efficiency by promoting diaphragmatic (belly) breathing.
  • DESIGNED TO HELP IMPROVE OXYGEN FLOW.
    This inspiratory exerciser benefits those undergoing respiratory treatment. The Breather is a respiratory trainer or exerciser that improves lung strength and capacity by increasing oxygen uptake to vital organs.
  • DRUG-FREE THERAPY FOR COPD, CHF, AND DYSPHAGIA
    The Breather is used by those affected by COPD, CHF, dysphagia, and neuromuscular disease. Continued use has improved dyspnea, peak cough flow, laryngeal function, QOL, vent weaning, and speech and swallowing performance.
  • ONLINE VIDEOS AND A DEDICATED MOBILE APP.
    PN Medical, creators of The Breather, offers self-paced, online video protocol training for therapists, patients, and consumers. Additionally, the Breather Coach mobile app lets you track and monitor your progress from your phone.
  • There are five expiratory and six inspiratory adjustable independent pressure settings. You can adjust the resistance on each inhalation and exhalation. The higher the setting, the higher the resistance.

CLINICAL BENEFITS

The Breather exercise optimizes the blood flow to your working muscles, increasing your performance capacity and extending your exercise limits. It improves the strength of your diaphragm and other respiratory muscles while maximizing lung function. The exercise strengthens your cardiac system and circulation, reducing blood pressure and improving sleep.

Special techniques of breathing exercises

Sound gymnastics

It is a unique breathing exercise consisting of pronouncing consonant sounds in a certain way – buzzing (zh, z), sibilant and hissing (s, f, ts, ch, sh), growling (r), and their combinations. In this case, the vibration of the vocal cords is transmitted to the smooth muscles of the bronchi, lungs, and chest, relaxing the spasmodic bronchi and bronchioles. Sound gymnastics aims to develop the correct ratio of inhalation and exhalation – 1: 2 (1.5). All sounds should be pronounced in a strictly defined way, depending on the purpose of gymnastics. For example, in bronchial asthma, buzzing, growling, and hissing sounds are pronounced loudly, energetically, exciting, and in chronic obstructive bronchitis with severe respiratory failure – softly, quietly, acceptable in a whisper (soothing).

Method of volitional elimination of deep breathing (VEDB) K.P. Buteyko

This technique originated in 1960 when Novosibirsk doctor K.P. Buteyko developed it. Its goal is to voluntarily correct incorrect (deep) breathing and gradually eliminate it. This is important because deep breathing can lead to a lack of carbon dioxide in the blood. Consequently, this deficiency causes a shift in the acid-base balance towards alkalosis and results in tissue hypoxia. When low carbon dioxide levels, oxygen binds firmly to hemoglobin and fails to enter cells and tissues.

The main tasks of the VEDB method are:

  • to normalize the ratio of inhalation and exhalation,
  • to reduce the speed and depth of inhalation,
  • to develop a compensatory pause after a long and calm exhalation,
  • to normalize the carbon dioxide content in the blood,
  • to reduce the number of asthma attacks and prevent their occurrence.

Paradoxical breathing exercises

These exercises help relieve an attack of suffocation. Gymnastics is called “paradoxical” because inhalation and exhalation are performed simultaneously with the movements of the arms, trunk, and legs, complicating this breathing phase. When the chest is compressed, inhalation is made, and when the chest expands, exhalation is made. The inhalation should be short, sharp, noisy, active, and forced by the diaphragm; exhalation occurs passively and spontaneously. Inhalation is carried out only through the nose, exhalation independently, passively (so that it is not audible), preferably through the mouth. You should not delay exhalation. 

The action mechanism of paradoxical respiratory gymnastics on the body consists of restoring disturbed nasal breathing, improving the drainage function of the bronchi, and activating the work of the diaphragm and chest muscles. Gymnastics promotes the resorption of inflammatory formations, the restoration of normal lymph and blood supply, and the elimination of local congestion. Eliminating morphological changes in the bronchopulmonary system enhances alveoli and tissue respiration gas exchange. It leads to an increase in oxygen absorption by tissues, which has a positive effect on metabolic processes. The coordination of breathing and movement helps to restore the regulation of breathing by the central nervous system, improves the psycho-emotional state, and has a general tonic effect.

The Role of Modern Oriental Respiratory Techniques and Pulmonary Rehabilitation in Health Recovery

Modern oriental respiratory systems, such as qigong, tai chi, and hatha yoga, focus on voluntarily controlling breath depth and frequency while balancing inhalation and exhalation. In these practices, the diaphragm plays an active role in breathing, and concentration and relaxation are equally important. Learning specific types of breathing—such as upper chest, costal, diaphragmatic, and full breathing—also becomes essential. Eastern breathing techniques are often promoted by enthusiasts and used in alternative medicine. Beyond their physical benefits, these techniques carry philosophical meanings to achieve harmony, harness inner strength, and enhance overall health.

To determine if a technique is suitable, one should consider one’s health status after exercise. Physical activity, in general, directly improves muscle function, motivation, mood, and symptoms. It also positively impacts the cardiovascular system, contributing to overall well-being.

Video – How to perform pulmonary rehab exercises at home

Special Considerations for COVID-19 Pulmonary Rehab

For individuals recovering from COVID-19 and undergoing pulmonary rehab, it is essential to consider the risk of pulmonary rehab exercise at home desaturation due to impaired gas transfer. Monitoring oxygen saturation levels may be necessary, and some individuals may require supplemental oxygen during rehabilitation exercises. Pulmonary rehabilitation programs should integrate both physical and psychological components and begin as early as possible after hospital discharge. Ideally, rehabilitation should continue for weeks or months to promote full recovery. By extending this support, patients are less likely to experience long-term disability after pneumonia and more likely to regain health.

THE ROLE OF RESPIRATORY (BREATHING) AND HRV BIOFEEDBACK IN PULMONARY REHAB AFTER COVID-19

Respiratory (breathing) and Heart Rate Variability (HRV) Biofeedback is a relatively new method of teaching people to change the parameters of respiration and cardiac activity. Recent research indicates the effectiveness of these biofeedback modalities in the treatment of many medical and psychological conditions, including:

  • anxiety disorders,     
  • depression,
  • asthma,
  • chronic obstructive pulmonary disease,
  •  cardiovascular diseases,
  • cardiac rehabilitation,
  • hypertension of various origins,
  • chronic fatigue,
  • chronic muscle pain,
  • post-traumatic stress disorder (PTSD),
  • insomnia
  • and other conditions, as well as to improve performance and professional efficiency.

Since the onset of the coronavirus pandemic, breathing and HRV biofeedback have been widely used in pulmonary rehabilitation after COVID-19.

Breathing and HRV biofeedback are not separate forms of therapy/training but are part of a larger multimodal team approach to pulmonary rehab exercises after COVID-19.

What is the mechanism of action and effectiveness of breathing and HRV biofeedback in pulmonary rehabilitation after COVID-19?

The HRV biofeedback technique includes training in breathing at the resonant frequency of the cardiovascular system. Breathing at this rate causes the heart rate to increase and decrease in the same phase as breathing. The heart rate increases with inhalation and decreases with exhalation. Then, the efficiency of gas exchange in the respiratory tract is maximal. The higher the HRV indicator (that is, the greater the difference in heart rate during inhalation and exhalation), the higher the degree of organism adaptation to the different external and internal stressors.

HRV biofeedback stimulates a specific reflex in the cardiovascular system with a particular rhythm. It is called “baroreflex” and helps control blood pressure. It also helps control emotional reactivity and improves breathing efficiency. Baroreflex is controlled by the nucleus of the solitary tract located in the brainstem. This center communicates directly with the amygdala, the center of emotional control, through a pathway through the islet. It is perhaps for this reason that various studies have shown the beneficial effects of respiratory biofeedback and HRV in the treatment of anxiety, phobias, and depression.

When blood pressure goes up, the baroreflex causes the heart rate to go down, and when blood pressure goes down, the heart rate goes up. This causes a rhythm in heart rate fluctuations. The baroreflex system resonates when a person breathes at this exact rhythm (which varies among people, generally between 4.5 and 6.5 times a minute).

How do we find the frequency at which the baroreflex system resonates for each person?

This frequency will produce the most significant swings in heart rate between inhaling and exhaling. To find this frequency, a person should try to breathe at various rates per minute to find the exact frequency at which the cardiovascular system resonates. This will be his/her resonance breathing frequency. This frequency varies from individual to individual, but it is approximately 0.1 Hz or six breaths per minute. The baroreflex system is stimulated and strengthened when people breathe at this frequency. Through projections to other systems in the body (e.g., inflammatory and limbic systems), different events occur that produce the many beneficial effects of HRV biofeedback. These changes are achieved with the help of HRV biofeedback training.

The Benefits of Controlled Breathing and HRV for COVID-19 Recovery

At around six breaths per minute, controlled breathing enhances internal regulation by establishing a balanced respiratory cycle. With each cycle, this method creates pronounced shifts in the autonomic nervous system, smoothly transitioning from parasympathetic to sympathetic states and back again. Heart rate variability (HRV) reflects this dynamic balance between sympathetic and parasympathetic influences on the heart rate, which signals autonomic flexibility. This flexibility represents the body’s ability to respond in a well-regulated way to various stimuli.

The resonance of the baroreflex circuit amplifies respiratory sinus arrhythmia, resulting in significant fluctuations in vascular tone, heart rate, and blood pressure. This ideal balance of relaxation and alertness supports homeostatic functions, optimizes neurovisceral integration, enhances efficient gas exchange in the lungs, reduces pain perception, stimulates anti-inflammatory responses, and builds resistance to both physical and emotional stress. Because of these benefits, patients with COVID-19 are encouraged to practice controlled breathing at a rate of six breaths per minute in the early stages of the disease. This practice promotes neuromodulation and may help prevent vascular and immuno-inflammatory complications.

Pulmonary Rehabilitation with Breathing and HRV Biofeedback

Incorporating breathing exercises and HRV biofeedback into COVID-19 pulmonary rehabilitation accelerates lung function recovery, restores tone in respiratory and skeletal muscles, and improves gastrointestinal and psychoemotional health. This comprehensive approach may also prevent pulmonary complications following COVID-19, offering holistic support for full and sustained recovery.

HOME-USE PERSONAL BIOFEEDBACK DEVICES FOR PULMONARY REHABILITATION AFTER COVID-19

Today, thanks to the development of technology, there are many HRV and breathing biofeedback devices for personal use at home.

Various companies have developed and presented commercial products ranging from $80 to $200.
The main requirements for HRV and breathing biofeedback devices for personal use are that the equipment must have a sensor for measuring heart rate (heart rate variability) using an electrocardiogram (ECG) and a respiration sensor using a breathing belt (recording the respiratory rate).

The eSense Respiration and eSense Pulse HRV Biofeedback devices are the most effective home-use devices for breathing and HRV biofeedback, allowing individual home comfort training.

HRV in sport performance

Heart Rate Variability in Athletes

Heart rate variability in athletes has gained significant attention as a crucial indicator of physical fitness and recovery. This metric reflects the body’s ability to adapt to stress and is particularly valuable for monitoring the training and performance of athletes. Analyzing the HRV of athletes, coaches, and trainers can gain insights into an athlete’s autonomic nervous system activity, recovery status, and overall well-being. Understanding heart rate variability (HRV) helps optimize training loads and plays a vital role in preventing overtraining and injuries. In this article, we will explore the importance of HRV in athletes, its impact on performance, and how it can be effectively utilized to enhance athletic outcomes.

Athletes' Pursuit of Improvement and the Role of HRV

As an athlete, you always look for that 1% improvement in every aspect of your game. However, as elite athletes improve and the margin for improvement narrows, achieving a 1% improvement becomes harder. With that in mind, athletes are conditioned to revert to the “train harder” mentality to grab that 1%. This mentality doesn’t always work because, much too often, overtraining and injuries occur. If you want to ensure your body is peaking at the right moments, having insight into HRV becomes that coveted 1% of all athletes are looking for.

Heart rate variability (HRV) represents variations between consecutive heartbeats (beat-to-beat or R-R interval) over time. This beat-to-beat variation in heart rhythm is considered normal and even desirable. When variations between consecutive heartbeats disappear, autonomic dysfunction is often the cause. This dysfunction can link to neurological, cardiovascular, and psychiatric diseases. Many studies show that higher heart rhythm variability relates to reduced mortality, improved quality of life, and enhanced physical fitness. (Learn more about Heart Rate Variability here).

Physiological Background and HRV’s Impact on Athletes’ Performance

The physiological background of HRV is complex and affected by circulating hormones, baroreceptors, chemoreceptors, and muscle afferents. An important factor influencing HRV is respiratory sinus arrhythmia – the natural variation in heart rate (HR) during breathingDuring inspiration, HR increases, whereas during expiration, HR decreases. The autonomic nervous system (ANS), through sympathetic (SNS) and parasympathetic (PNS) pathways, regulates the function of internal organs and the cardiovascular system. During training or competition, sympathetic activity (“fight or flight”) increases an athlete’s cardiac contractility, heart rate, breathing, and muscle tension.

In contrast, parasympathetic (vagal) stimulation (“rest and digest”) reduces an athlete’s heart rate, relaxes muscles, and allows for digestion. Any source of stress (psychological, physical, or illness) will provoke disturbance in the ANS and, consequently, in HRV. The long-term presence of an imbalance between sympathetic and parasympathetic tones can impair athletes’ performance.

HRV data offers a unique view into nervous system activity. This insight helps athletes find the right balance between training and recovery.

Heart rate variability in athletes

HEART RATE VARIABILITY IN ATHLETES DURING AND AFTER EXERCISE (INDICATORS OF STRESS/TRAINING LOAD)

During exercise, HRV is reduced (shorter R-R intervals), and heart rate is increased due to augmented SNS and attenuated PNS activity. Not only are the intervals between R-R peaks shorter, but they also become more uniform (reduced R-R variability).

The relationship between sympathetic and parasympathetic activity during exercise depends directly on training intensity. During physical activity, sympathetic nerves can increase cardiac output to 2 to 3 times the resting value.

Caution should be taken when interpreting HRV analysis during exercise. When exercise intensity exceeds 90% of VO2 max, breathing frequency rises. This increase boosts vagal contribution, or PNS activity, due purely to the heart’s mechanical properties rather than any neural input from the ANS. As a result, PNS activity, driven by faster respiration, can mask actual SNS activity at these higher intensities. To ensure accurate results, the athlete should maintain a stable respiration rate as much as possible during an incremental test to exhaustion.

TRAINING LOAD

The distribution of training loads is a fundamental component of periodization. The elements that comprise the training load are training volume and intensity. The interplay between these two elements will define the total training load. Higher training loads will cause greater ANS disturbance and sympathovagal imbalance. Post-exercise HRV analysis appears to be a valuable indicator for evaluating variations in performance level and can indirectly reflect training loads. There is evidence that HRV parameters are highly correlated with the intensity and volume of exercise and are inversely related to the training load level.

RECOVERY AND HEART RATE VARIABILITY IN ATHLETES PERFORMANCE

Understanding Stress, Adaptation, and Recovery in Training

On the assumption that physical activity causes stress (a stimulus), the body will respond with a stress reaction on different physiological levels. In addition to a stress reaction, adaptation processes occur during recovery. Suppose the magnitude of the stress stimulus (training load) is high enough (overload principle) to evoke a reaction in the body. In that case, the response will be proportional to the stress level, and, as a result, greater training effects will be accomplished (adaptation).

To reach higher performance levels in sports, it is essential to understand that well-designed and integrated rest periods are crucial. Recovery after training is considered an integral part of the training methodology. Performance will not improve if there is a lack of optimal recovery. Problems occur when the demands are so frequent that the body cannot adapt. This means the body will continuously be under sympathetic domination during rest and activity.

Most athletes and sports science personnel understand the importance of recovery after exercise, defined as the return of body homeostasis after training to pre-training or near pre-training levels.

The Role of Recovery and Its Impact on Performance

Recovery involves getting adequate rest between training sessions/competitions to allow the body to repair and strengthen itself in preparation for the subsequent bout. Optimal athletic performance is supported when recovery to pre-training or near pre-training levels is permitted. If recovery is insufficient, hindrance of physiological adaptation and reduced athletic performance should be expected. Recovery plays a major role in minimizing the harmful effects of training (fatigue) while retaining the positive impact (improved fitness/strength/performance).

Without monitoring recovery after exercise, fatigue can build up and become excessive before competition. This buildup reduces athletic performance and may even lead to overtraining syndrome. The overtraining syndrome occurs when training stress is too high, and recovery is insufficient, causing fatigue and decreased performance.

Heart rate variability in athletes performance: Train-Recover-Perform

Every training session stresses the body and disturbs homeostasis and ANS modulation. These changes in ANS activity manifest as increased sympathetic activity or decreased parasympathetic activity, which reflects in HRV parameters. One crucial aspect of recovery is sleep, during which parasympathetic activity should dominate. However, an optimal recovery state typically features parasympathetic (vagal) predominance of the ANS, regardless of the time of day.

HRV as a Noninvasive Tool for Monitoring Recovery

Various parameters can be used to measure post-exercise recovery (VO2 max, creatine kinase, C-reactive protein, plasma cortisol, blood leukocyte, myeloperoxidase protein level, and glutathione status). However, these methods are mostly invasive, time-consuming, and expensive for everyday use. Accordingly, the importance of a noninvasive, easy, and affordable method to evaluate recovery is obvious. Thus, HRV technology is increasingly used to evaluate the status and level of recovery.

Long-term high-intensity training sessions gradually decrease the parasympathetic component of HRV, which increases during the rest of the period. The sympathetic component demonstrates the opposite tendency.

Reactivating HRV’s parasympathetic activity to pre-exercise levels as quickly as possible significantly improves athletes’ recovery. When HRV parameters cannot return to pre-exercise or optimal levels within a reasonable time, this indicates a chronic disturbance in ANS activity. Such a disturbance can lead to overtraining.

Today, HRV-based devices and software assist in athletes’ recovery analysis, providing easily interpretable data to trainers and athletes. The most common procedure to evaluate recovery level involves overnight measurement (nocturnal) of HRV, although systems that can assess a quick recovery index (5-minute measurement) are also available.

THE USE OF HEART RATE VARIABILITY IN ATHLETES: OVERTRAINING AND HOW AVOID IT?

Sometimes, the line between optimal performance level and overtraining is skinny.

Overtraining syndrome (OTS) results from a long-term imbalance between stress (internal and external) and recovery periods. A large body of evidence implies that overtraining syndrome causes significant cardiac autonomic imbalance between the two ANS pathways (sympathetic and parasympathetic).

The literature contains conflicting results about ANS modulation in overtrained athletes. Some studies report a predominance of sympathetic and parasympathetic autonomic tone during an overtrained period. The description of different types of overtraining might explain these disputed results.

Two types of OTS have been reported: sympathetic and parasympathetic overtraining, each with specific physiological characteristics.

Sympathetic tone

Insomnia

Irritability

Tachycardia

Agitation

Hypertension

Restlessness

Parasympathetic tone

 

Fatigue

Bradycardia

Depression

Loss of motivation

 

The early stages of performance impairment feature sympathetic domination of the ANS at rest. This condition is often called an “overreaching state” or “short-term overtraining.” This means that the disturbance of homeostasis was not high and long enough to provoke a chronic overtraining state. Therefore, the time needed to fully recover all physiological systems typically encompasses several days to weeks.

Sports that require higher exercise intensity generally show increased sympathetic tone. If the overreaching state (sympathetic autonomic tone domination) continues for longer, OTS and domination of parasympathetic autonomic tone will develop. Parasympathetic OTS dominates in sports characterized by high training volume.

LIMITATIONS, IMPROVEMENTS AND FUTURE PERSPECTIVES OF ANALYSIS OF HEART RATE VARIABILITY IN ATHLETES PERFORMANCE

Analysis of heart rate variability in athletes’ performance has become a widely accepted method for noninvasive evaluation of ANS modulation during and after exercise. To overcome the aforementioned disadvantages, the recording signal must contain a minimum of 5 minutes of HRV fluctuation to get reliable results.

In the last 5 years, the number of devices and software programs/apps using HRV technology has increased exponentially. The current trend in software engineering is to make all wireless sensors for capturing and transmitting HRV data compatible with smartphones. Hardware and software engineers are continuously improving the accuracy of sensors that record and receive HRV signals (heart rate belts, wireless technologies, and protocols) and HRV analysis techniques (software, mathematical models). This provides the trainer and athlete with quick and easy analysis of HRV data during and after a training workout (training load, recovery, and overtraining).

THE GOAL OF MONITORING OF HRV IN ATHLETES PERFORMANCE

HRV provides an excellent objective status of the autonomic nervous system. The primary goal is reducing injuries, decreasing overreaching, improving player health, increasing adaptation, and learning more about training. However, winning requires that talent is available and optimized in performance, not just uninjured. The essence of monitoring heart rate variability in athletes is to drive a routine and accountability process for winning. The data collected from HRV can guide athletes like a compass to a training program blueprint, but only if the commitment exists with everyone. Winning requires talent and preparation, and while only a few can be on top of the mountain, HRV can increase those odds if appropriately used.

MEASUREMENT PROTOCOL

Metrics

  • RMSSD is the most commonly used and trusted metric. It is a clear marker of parasympathetic activity (recovery). RMSSD is linked to performance changes, fatigue states, overreaching, and overtraining. The return of RMSSD to baseline after exercise has been related to the clearance of plasma catecholamine, lactate, and other metabolic byproducts, in addition to restoring fluid balance and body temperature.
    Therefore, RMSSD serves as a global marker of homeostasis, reflecting various aspects of recovery. This marker may explain why planning intense training when HRV is at or above baseline can help improve endurance performance.
  • Duration: 60 seconds to 2 minutes in the morning is the ideal measurement protocol for reliability and practical applicability in team settings. Night measurements are also a valid method.
  • Frequency: To establish a valid baseline, at least three days per week are required. More measurements can be beneficial, up to five ideally. If compliance is an issue, prioritize the three days in the middle of the week, far from matches, to avoid residual fatigue.

Data analysis: The most important parameters to examine are baseline HRV and the coefficient of variation (CV).

  • HRV baseline: computed as the average HRV over a week (or 3-5 days if daily measurements are challenging to obtain). An athlete’s average values should be analyzed. Typical values are a statistical way to represent historical data collected in the previous 30 to 60 days. This should give us insights into where we expect the HRV baseline to be, provided no significant stressors are present. In case of such significant stressors or issues in responding to training or lifestyle stressors, the baseline will deviate from the expected typical values.
  • CV: Coefficient of Variation, or the amount of day-to-day variability in HRV.

Insights

Pre-session: load can be adjusted based on individual responses as shown in baseline HRV and CV. In particular:

  • Athletes showing a reduced HRV and increased CV most likely struggle with the load and might benefit from reduced load or other recovery strategies (sleep, diet, yoga, or different ways to minimize non-training-related stress, for example).
  • Athletes showing a stable or increasing HRV are likely coping well with the increased load.
  • Athletes showing a reduced CV likely cope well with the increased load unless their baseline HRV reduces or goes below average. In this case, the reduced CV might highlight an inability to respond to training.

The same patterns throughout the session can help you understand individual responses to changes in training load. Use HRV as a continuous feedback loop rather than a target to optimize toward a specific value. Staff working with athletes and physiological measures should prioritize baseline and CV changes to determine individual responses and adaptations.

HRV ADDITIONAL INFORMATION AND PRACTICAL RECOMMENDATION

  • HRV is an indication of your resilience – the ability of the nervous system to respond and recover from physical or psychological stressors;
  • HRV values depend on the length of the measurement
    – 5 minutes = short term HRV
    – 24 hours = long term HRV;
  • HRV is age and gender-dependent;
  • HRV has a circadian rhythm;
  • HRV may change day to day with your biorhythm or due to emotional or physical stress;
  • HRV is dependent on body position;
  • Chronic low HRV is an indication of systemic health (psychological or physical) issues;
Circadian Rhythm of HRV
HRV and body position
  • HRV measurement should be provided for the same length of time each day (3 minutes typical);
  • HRV should be taken at the same time each day
    – First thing in the morning is recommended
  • HRV should be taken in the same position
    – Lying down
    – Sitting
    – Standing

ESENSE PULSE WEARABLE ECG MONITOR

Heart Rate Variability (HRV) refers to the variable time between individual heartbeats. An ECG can accurately measure HRV. A basic heart rate monitor can also provide this data, but the HRV will not be as accurate.
Only elite athletes and their coaches had access to HRV data in the past because devices that measure ECG were costly and difficult to wear.

In the last five years, innovations in wireless technology have significantly increased the number of devices on the market that use HRV indices to control and manage athletes’ training processes. Now, with accessible, wearable, and user-friendly technology like the eSense Pulse wearable ECG monitor, everyone from professional athletes to weekend warriors can use HRV data to enhance their training.

TARGET HEART RATE

While using eSense Pulse, the eSense App displays the current heart rate and the target heart rate during recording in the overview area. The target heart rate can be adjusted at any time in the settings of your eSense App. You can either set it directly or as a percentage of the predicted maximum heart rate. By default, the target heart rate value is 85% of the expected maximum HR.

The predicted maximum heart rate is calculated using the following formula: Predicted Maximum Heart Rate = (220—your age in years). Normally, you should maintain your heart rate below your target level (85% of a predicted maximum heart rate, based on your age and medical conditions).

HRV focuses on the distance between peaks. In the eSense App, the SDNN (Standard deviation of all NN intervals) and RMSDD (Root Mean Square of the Successive Differences) is one of a few time-domain tools used to assess heart rate variability, the successive differences being neighboring RR intervals) values relate to the time interval between peaks, but RMSDD best shows parasympathetic or “rest and digest” activity. Accurate RMSDD measurements can also be taken in 60 seconds or less, which makes RMSDD quick and easy.

HOW CAN RMSDD BE USED TO CALCULATE HRV AND PLAN OPTIMAL ATHLETIC TRAINING?

The power of HRV as a training tool comes from establishing an RMSDD baseline. To establish a baseline, an athlete needs to wake up, strap on the eSense Pulse for a minute, and take a reading each day for one week. At the end of the week, if they average all of their RMSDD measurements, they will have a baseline RMSDD number.

In the future, if their RMSDD numbers fall below their baseline in the morning, they will know to ease off on training for optimal performance. If their RMSDD number goes above their baseline, they are more than recovered and can take on a challenging workout. In other words, higher RMSDD numbers correspond with more parasympathetic activity or a more recovered state.

RMSDD AND HRV LET YOU KNOW WHEN AND HOW TO TRAIN

In a perfect world, an athlete’s mind and body would be in total sync, and athletes would intuitively know how hard to push themselves. In reality, athletes may gradually stop making progress without knowing exactly why. They are either over or undertraining. They may attribute their fatigue to not working hard enough when, in fact, they are working too hard. HRV measurements like RMSDD give athletes an objective way to justify a rest day or, on the other end of the spectrum, prompt them to increase the intensity and volume of the training. Heart rate variability in athletes used to be available only to world-class athletes. However, with technologies like eSense Pulse, HRV analysis can be used by cyclists, runners, endurance athletes, and even gym enthusiasts.

References

Bojan Makivic, Pascal Bauer – Heart Rate Variability Analysis in Sport, Utility, Practical Implementation, and Future Perspectives. Aspetar Sports Medicine Journal, p.326-331 – www.aspetar.com/journal

Simon Wegerif. – Using Heart Rate Variability to Schedule the Intensity of Your Training. – https://www.trainingpeaks.com/

Cian Carroll. – Monitoring An Athlete’s Internal Response: A Comprehensive Guide To Analysing Heart Rate Variability & Heart Rate Recovery. – https://statsports.com/