Heart Rate Variability

Heart Rate Variability

Heart Rate Variability or HRV is a measure that looks at the changes in the time between successive heart beats. Instead of being a measure of the number of heart beats in a given time (heart rate), HRV looks at the small changes in inter-beat-intervals (IBIs) in a given period of time. The inter-beat-intervals are also referred to as R-R intervals, reflecting the measurement of IBIs on an electrocardiogram (ECG) between the R (QRS) waveforms. HRV is typically measured in milliseconds (ms).

In measuring HRV, the frequency of heart rate signals is analyzed, as opposed to analyzing over time as with HR beats per minute. A mathematical process called “spectral analysis” is used to look at the HR power spectrum to determine the frequency of HR signals. Although heart rate over time (for example a one-minute HR) may be reasonably stable, the time between two heart beats can be considerably different. 

This rhythmic fluctuation occurs between heart beats because of the changes in the sympathetic-parasympathetic balance that controls sinus rhythm in the heart. By looking at HR variability you can “noninvasively evaluate the relative contributions of the sympathetic and parasympathetic nervous system at rest and during exercise. There are many physiological influences on HR variability frequency domains.” (Kenney 2019)

  • When the sympathetic nervous system (stress/fight or flight) is more active, you will see a lower HRV. When the parasympathetic nervous system (rest, digest, repair) is more active, you will see a higher HRV.
  • Influence is exerted in the sympathetic branch through the release of adrenaline which acts on nicotinic acetylcholine (ACh) receptors allowing the body to respond to challenges to survival.
  • In the parasympathetic system, the vagus nerve and vagal tone respond to ACh to help conserve and restore energy by reducing heart rate, blood pressure, and the digestive system. (Singh 2019)

At this time, HR variability is primarily being used to examine physiological parameters in a few different ways:

  • in chronic disease risk, cardiovascular disease risk, and health indications
  • in looking at the impact of exercise training, especially in reference to functional and non-functional over-reaching, over training, and recovery.

HR variability is also considered an interesting marker for resilience and behavioral flexibility with applications for psychological and behavioral health.  “It is well established that low HRV is associated with a broad range of medical and psychological health problems.” (Wheat 2010) 

The goal is to maintain balance between the sympathetic and parasympathetic branches. “If we have persistent instigators such as stress, poor sleep, unhealthy diet, dysfunctional relationships, isolation or solitude, and lack of exercise, this balance may be disrupted, and your fight-or-flight response can shift into overdrive.”  HR variability can give insight into the ANS and be a valuable preventive tool metric.

A reduced HR variability (sympathetic) is associated with: 

  • worsened anxiety and depression
  • increased risk of cardiovascular disease and death
  • myocardial infarction
  • chronic heart failure
  • unstable angina
  • diabetes mellitus

An increased HR variability (parasympathetic) is associated with: 

  • better cardiorespiratory fitness
  • resilience to stress
  • lower risk for many chronic diseases

A heart rate that is variable and responsive to demands is believed to bestow a survival advantage. The ability of the autonomic nervous system and sinoatrial node to respond dynamically to environmental changes results in increased HRV and generally indicates a healthy heart. A reduction in HRV is believed to indicate an inability or attenuation in the autonomic nervous system’s or sinoatrial node’s responsiveness to change. 

HR variability moves to a healthier level with:

  • more mindfulness
  • meditation
  • sleep
  • physical activity (Faye 2010)
  • regular aerobic exercise which increases vagal tone (Singh 2019)

Monitoring the autonomic nervous system (ANS) with HRV has become a useful tool for cardiovascular health and fitness:

  • providing insight to cardiovascular risk evaluation and diagnosis.
  • using HRV to alert athletes of overtraining and to optimize training. (Singh 2019)

A resting ECG for a healthy individual will show obvious high frequency values. HRV can lower with aging, sedentary lifestyle, mental load, and possibly overtraining. (Singh 2019) Cardiorespiratory exercise training increases vagal tone therefore increasing HRV.

HRV is the beat-to-beat alteration of the R-R interval of your heart rate. The gold standard for measuring HR variability is to analyze a strip of an electrocardiogram (ECG) to determine the IBIs. With this method being impractical and unavailable to the general public, HRV can also be tracked with a HR/heartbeat monitor (finger/wrist device or a chest strap) and the purchase of an app to analyze the data. There are other ambulatory methods for measuring HRV, many of which are not practical to use at this time but may become more practical as technology advances.

Common metric measurement devices use the following technology: (Singh 2019)

  1. ECG Devices: measurement of ECG still remains the most accurate way to measure HRV. Single lead ambulatory devices are available to analyze HRV.
  2. Photoplethysmography (PPG): “an optical technique that detects blood volume changes in the microvascular bed of tissue under the skin’s surface.” (Singh 2019) This method can be affected by motion and skin characteristics. It measures lower frequency components (sympathetic) and changes in blood volume with each heartbeat. Interest in PPG for measuring HRV is rising due to accuracy and wear ability, but there has been limited validation of this method for tracking HRV. Ongoing research is in progress to improve the accuracy of this method.


  • Most wrist worn tracking devices depend on PPG. Some now are adding ECG sensors.
  • Chest straps with ECG electrodes that record ECG signals are more accurate. Some will send RR data to a cell phone via wireless technology. (Singh 2019)
  • Wearable technology (PPG and ECG) for individual use, research use, and metric monitoring for health and disease risk continues to advance with HRV being a metric in the spotlight.
  • Validity of wearables must continue to be studied for risk stratification, accuracy, and reproducibility. (Singh 2019)

When and How to Measure HRV (www.AgelessInvesting.com)

  • HRV should be measured while you are sitting or standing upright. Parasympathetic saturation, a phenomenon caused while lying down, makes trends in HRV harder to interpret.
  • HRV is best taken in the morning because your cortisol awakening response will make the reading different at any other time.
  • Therefore, if you can’t take the reading within an hour of your usual time then don’t take it that day. Taking your reading at the wrong time will not accurately represent your awakened state and you may alter your baseline.

Emerging Science
Heart Rate Variability is a metric that is growing in interest and understanding. Using HRV as an indicator of heart disease and increased risk of sudden cardiac risk will provide non-invasive evidence that may be a catalyst for change in lifestyle habits for many at risk. HRV and the vagal response are also linking the predisposition and development of chronic disease directly to the importance of adequate sleep, stress reduction, mindfulness, and relaxation. This is a game changer, making the importance of “chilling out” and getting enough quality sleep something that goes from a luxury to a strong necessity that needs to be deeply entrenched in daily life. It is essential to health and quality of life. Our growing understanding of the role physical activity plays in HRV and vagal response will hopefully drive future generations to make physical activity a globally accepted way of daily life.

To Learn more about Heart Rate Variability and Heart Rate Training see the NAFC PowerCert: Heart Rate-Based Training for All Applications to earn .6 CECs. 


  • Kenney WL, Wilmore JH, Costill DL. (2019) Physiology of Sport and Exercise. 7th Human Kinetics.
  • Wheat AL, Larkin KT. (2010) Biofeedback of Heart Rate Variability and Related Physiology: A Critical Review. Appl Psychophysiol Biofeedback (2010) 35:229–242.
  • Singh N, Moneghetti KJ, Christle JW, Hadley D, Plews D, Froelicher (2019) Heart Rate Variability: An Old Metric With New Meaning In The Era Of Using MHealth Technologies For Health And Exercise Training Guidance. Part One: Physiology and Methods. US Cardiology Review VOL13: Issue 1: Spring 2019. https://www.aerjournal.com/articles/Heart-Rate-Variability-MHealth

Understanding the Seven Stages of Grief and Chronic Illness

Understanding The Seven Stages of Grief and Chronic Illness

It is essential to understand the Seven Stages of Grief and chronic disease if you plan to work with clients living with a chronic disease. Many individuals have heard of the five stages of grief created by Elizabeth Kubler-Ross in 1969. This model is used to explain the stages of grief over the loss of a loved one. There has been an updated model called the Seven Stages of Grief for Chronic Pain and Chronic Illness by Dr. Jennifer Martin, PsyD of www.imaginelifetherapy.com

According to imaginelifetherapy.com, there are seven stages of grief for chronic disease: denial, pleading, bargaining and desperation, anger, anxiety and depression, loss of self and confusion, and acceptance. Clients can go from one stage to another until finally reaching acceptance. An individual, for example, can go from denial to anger and back to denial. Everyone will go through the stages in their own way and timing. There is no set time for anyone to reach acceptance of their situation. If your client can see positive changes after working with you, their outlook will be more positive. As they become stronger and learn more skills, clients will become more ambulatory and be able to move more over time.

Many times, clients will be experiencing their symptoms (chronic disease symptom cycle) and the stages of grief simultaneously. We usually think of grief with respect to the loss of a loved one. With chronic disease, your client may be grieving the life they used to live. Knowing that their lives may changed because of an illness is very stressful. In addition, the individual may be thinking about the future and how their health will be ten years from now. As a health fitness professional, you need to help your client to be present and in the moment. Help them understand and focus that the work they do today will influence how mobile they are ten years from now. If they are discouraged by the big picture, it will be harder for them to stay focused.

Each stage of grief has its own parameters and can give you insight as to which stage the client is currently in. Empathy and support are a critical part of helping a client to get through the stages of grief. Tailor exercise programming to what your client can handle each time they train. If they are having a rough day, you can offer the client a meditation session instead of a training session. Having options to meet them where they are each session may improve compliance if they are not mentally or physically ready for an exercise session.

Adapted from: Pratt, Amanda. “7 Stages of Grief for Chronic Pain and Chronic Illness: St. Petersburg Therapist.” Chronic Illness Therapy, 3 Aug. 2018, imaginelifetherapy.com/7-stages-of-grief-for-chronic-pain-and-illness/.

To know which stage of grief a client may be in, you must have an understanding of each stage.

Denial: The individual has just been diagnosed and is in shock. They cannot believe that they have been diagnosed with a chronic disease. They start to wonder how they will make changes and live a good life. Shock can help the person to decide to move on to the next stage and start working through the stages. It may also backfire if the individual chooses to think that the condition will eventually go away or be okay. Sometimes denial presents as pretending the chronic disease is not happening.

Pleading, Bargaining, and Desperation: In this stage the client tries really hard to bargain or plead to not have a chronic illness. The individual also wishes really hard that they could go back to their previous life. They may feel guilty and blame themselves for becoming sick and wondering if they could have done more to prevent their illness. Guilt usually comes with bargaining as the person blames themselves for their situation.

Anger: This is a crucial stage for individuals to begin the healing process. There is no specific timeline for the client to get through the anger stage. Please note that a client may come in angry some days when training. Try to remain empathetic and patient as the individual goes through this stage. Keep in mind that everyone on the healthcare team often sees anger from the newly diagnosed individual. It is normal for the client to be angry at their doctor, caregiver, family, friends, and even you, their trainer. However, they will most likely apologize after showing you that they are visibly angry. Anger typically comes later in the process when the disease progresses, and the individual realizes that life will change.

Anxiety and Depression: These will set in next as life changes are solidified. The feelings of depression can be substantial and seem to the client like they will never go away. If a client starts to withdraw, offer meditation instead of a training session to keep the client on track. Try to also be understanding about their condition and how they are feeling. If they must cancel with you, ask that they do so within a certain amount of time as your time is valuable as well. There may be anxiety about the future and the unknown as the person wonders what will happen to them.

Loss of Self and Confusion: This can be very real for individuals with a chronic illness. In this stage, life has changed so much for this individual that they do not recognize themselves. Some people define and understand themselves by what they can do. Due to the chronic illness, they can no longer do what they used to do in the same way and  they have to figure out how to redefine themselves. This stage may happen at the same time as anxiety and depression or separately.

Re-evaluation of Life, Roles, and Goals: The client will be thinking about how they can move forward as a wife, mother, husband, father, sibling, and friend. They are forced to re-evaluate how they fit into the picture of their new life and what that means in daily life, figuring out how to go about daily activities, and what work will look like for them.

Acceptance: This is the final stage in which the client accepts his or her new reality. The client is not usually happy with it, but they learn how to deal with their new norm. They strive to learn new skills to make life better and discover new things that bring joy into their lives. In this stage, the client will be most accepting of trying new exercises and stress relief modalities in their training sessions.

Adapted from: Pratt, Amanda. “7 Stages of Grief for Chronic Pain and Chronic Illness: St. Petersburg Therapist.” Chronic Illness Therapy, 3 Aug. 2018, imaginelifetherapy.com/7-stages-of-grief-for-chronic-pain-and-illness/.

Robyn Caruso is the Founder of The Stress Management Institute for Health and Fitness Professionals. She has 20 years of experience in medical-based fitness.

Risk Factors and Stages of Alzheimer’s Disease

Risk Factors and Stages of Alzheimer’s Disease

The information in this post is from the Alzheimer’s Prevention and Intervention Specialist Certificate Program: Course 1: Exercise Prescription for Alzheimer’s Prevention and Intervention.
Authored by Dharma Singh Khalsa M.D., Founding President/Medical Director of Alzheimer’s Research and Prevention Foundation.

There is a growing body of research on modifiable risk factors for dementia. However, modern medicine still hasn’t discovered all the answers in this field. Therefore, prevention supports available evidence targeting risk factors for vascular disease such as diabetes, hypertension, obesity, smoking, hyperlipidemia, and physical inactivity. (Dementia: A World Health Priority 2016) Many of these risk factors can be controlled effectively by making healthy lifestyle choices to aid in the prevention of Alzheimer’s disease.

Most experts believe that Alzheimer’s disease, similar to other common chronic diseases, develops as a result of multiple factors instead of a single cause. They also support the idea that some risk factors can be controlled by making smart lifestyle choices.

Physical exercise on a regular basis is a valuable habit to help decrease the risk of Alzheimer’s and vascular dementia. Exercise may benefit the brain cells directly by improving both oxygen and blood flow to the brain. An evidence-based and medically approved exercise program is recommended as part of an overall wellness plan. (Prevention and Risk of Alzheimer’s and Dementia 2016)

There are a number of risk factors that may lead to cognitive decline.
(Adapted from Alzheimer’s Risk Factors 2016 and 2016 Alzheimer’s Disease Facts and Figures 2016)

  • Age
  • Family History
  • Genetic Predisposition
  • Stroke
  • Depression
  • Head/Brain Injury
  • Lack of Adequate Sleep
  • Cardiovascular Disease and Risk Factors.
    • Smoking
    • Diabetes
    • Hypertension (high blood pressure)
    • High cholesterol
    • Physical inactivity
    • Obesity

Exercise is an important part of treatment. Research shows that it may help slow the progression of disease. Be patient and creative when working with clients who have Alzheimer’s disease. Have an understanding of the disease progression, be vigilant in identifying physical decline, and overall, adjust their exercise program to maintain safety. The seven stage model that is commonly accepted and used to stage the progression of Alzheimer’s is provided below. 

When working with clients, it is helpful to understand the stage of progression (often identified by disease symptoms) they are experiencing. This will give you ideas and guidelines for how to most effectively communicate and motivate the client in order to produce results. Different strategies may be required for communication, programming, and expectations during different stages of disease progression.

For more information on risk factors, risk factor reduction, stages of progression, and The 4 Pillars of Alzheimer’s Prevention™, see the FLS course Introduction to Alzheimer’s Disease. Or visit the Alzheimer’s Research and Prevention Foundation Website at www.alzheimersprevention.org.

Seven Stage Alzheimer’s Disease Progression Model for Help with Expectations during Disease Progression.
(Alzheimer’s Disease: Symptoms, Stages, Diagnosis and Coping 2016) 
(Reprinted with permission from HelpGuide.org)

Stage 1:
Subjective Cognitive Decline (SCD). No impairment. Memory and cognitive abilities appear normal, but individual complains of memory difficulties.

Stage 2: 
Minimal Impairment/Normal Forgetfulness. Memory lapses and changes in thinking are rarely detected by friends, family, or medical personnel, especially as about half of all people over 65 begin noticing problems in concentration and word recall.

Stage 3: 
Early Confusional/Mild Cognitive Impairment. While subtle difficulties begin to impact function, the person may consciously or subconsciously try to cover up his or her problems. Difficulty with retrieving words, planning, organization, misplacing objects, and forgetting recent learning, which can affect life at home and work. Depression and other changes in mood can also occur. Duration: 2 to 7 years.

Stage 4: 
Late Confusional/Mild Alzheimer’s. Problems handling finances result from mathematical challenges. Recent events and conversations are increasingly forgotten, although most people in this stage still know themselves and their family. Problems carrying out sequential tasks, including cooking, driving, ordering food at restaurants, and shopping. Often withdraw from social situations, become defensive, and deny problems. Accurate diagnosis of Alzheimer’s disease is possible at this stage. Lasts roughly 2 years.

Stage 5: 
Early Dementia/Moderate Alzheimer’s disease. Decline is more severe and requires assistance. No longer able to manage independently or recall personal history details and contact information. Frequently disoriented regarding place and or time. People in this stage experience a severe decline in numerical abilities and judgment skills, which can leave them vulnerable to scams and at risk from safety issues. Basic daily living tasks like eating and dressing require increased supervision. Duration: an average of 1.5 years.

Stage 6: 
Middle Dementia/Moderately Severe Alzheimer’s disease. Total lack of awareness of present events and inability to accurately remember the past. People in this stage progressively lose the ability to take care of daily living activities like dressing, toileting, and eating but are still able to respond to nonverbal stimuli, and communicate pleasure and pain via behavior. Agitation and hallucinations often show up in the late afternoon or evening. Dramatic personality changes such as wandering or suspicion of family members are common. Many can’t remember close family members, but know they are familiar. Lasts approximately 2.5 years.

Stage 7: 
Late or Severe Dementia and Failure to Thrive. In this final stage, speech becomes severely limited, as well as the ability to walk or sit. Total support around the clock is needed for all functions of daily living and care. Duration is impacted by quality of care and average length is 1 to 2.5 years.


7 Essential Guidelines for Exercise for Diabetics

7 Essential Guidelines for Exercise for Diabetics

November is Diabetes Awareness Month!
The information in this course is from “Exercise, Diabetes, and Metabolic Syndrome,” a continuing education course offered by NAFC.  

There are several precautions a client can take to not only prevent hypoglycemia, but to also have a safe exercise experience. Use these Guidelines to help your client avoid complications during exercise.

  1. Inject insulin in a part of the body that will not actively be used for exercise. The abdomen is recommended.
  2. Check blood glucose levels before, during and after exercise the first couple of exercise sessions and/or if trying a new activity.
    • Activity type, intensity, and duration may affect glucose levels.
    • Typically, 1 hour of exercise = an additional 15 grams of carbohydrates either before or after exercise.
  3. During exercise, a quick source of carbohydrates (that does not also contain fat) should be readily available such as orange juice or hard candy.
  4. Be aware of a delayed post-exercise hypoglycemia in those who take insulin.
    • Metabolism may remain elevated for several hours post-exercise especially during the night.
    • Check glucose at bedtime and again a couple hours after (~1-2AM) especially on a day of increased activity.
  5. Adequate fluids before during and after exercise are recommended.
  6. Wear proper shoes with polyester or blend socks as well as inspecting feet after exercise to practice good foot care.
  7. Carry medical identification.