Physiology of Heart Rate Variability

At its core, HRV is a measure of the tiny variations in time between consecutive heartbeats. These variations are like your heart’s way of dancing to its own unique rhythm, and they carry important information about your health (see the references, 1.-9.)

What is HRV?

Heart Rate Variability (HRV) is like a window into how well your body’s engine, the heart, is running. Imagine your heart as a car engine that speeds up and slows down as you drive. HRV measures these subtle changes in your heart rate. Scientists have discovered that when your heart rate varies a lot—like a car’s engine revving up and slowing down—it’s a sign that your body’s control system is working well. This control system, called the autonomic nervous system, manages everything your body does automatically, like breathing and digestion. HRV can show how balanced this system is (1.,2.,3.,4.).

Heart Rate Variability (HRV) is like a language the heart speaks to the brain, and the brain responds back. Imagine your heart is sending messages to the brain, saying, “I need more energy” or “I’m doing just fine.” HRV measures how varied and flexible these messages are (2.-6.).

 

  • Heart: Your Body’s Engine (2.,3.,4.)

      • The heart is like the body’s engine.
      • It’s a strong muscle in your chest, a bit bigger than your fist.

  • Continuous Pumping:

      • The heart works non-stop, pumping blood all over your body.

  • Blood: The Body’s Delivery System:

      • Blood carries oxygen and nutrients to all body parts.
      • It also helps remove waste and carbon dioxide.

  • Essential for Body’s Functioning:

    • The heart’s pumping is vital for the body to work well.
    • It ensures everything the body needs is delivered to the right places.

  • Brain: Your Body’s Supercomputer (2.,4.)

      • It’s like a control center in your head.
      • Helps you think, learn, and do things.

  • Memory Bank and Learning Hub:

      • Stores all your memories and experiences.
      • Learns new things as you go along.

  • Feelings and Emotions:

      • Lets you feel happy, excited, or even sleepy.
      • Makes experiences enjoyable, like laughter or excitement.

  • Overall Manager:

    • Acts like the boss, managing everything you do and feel.
    • Helps you interact with the world.

When the heart and brain have a good conversation, the heart’s rhythm changes smoothly and shows high HRV. This means the brain trusts the heart to adjust its pace based on what the body needs—like speeding up during exercise and slowing down during rest. It’s like a smart dialogue where the heart and brain work together, ensuring the body functions optimally (2.-6.).

Autonomic Nervous System

  • Autonomic Nervous System (ANS) (5.-9.):

    • This is like your body’s automatic control system.
    • A division of the Peripheral Nervous System 

  • Controls Involuntary Actions:

    • Manages things your body does automatically, like breathing and digesting food.

  • Two Main Parts:

    • Sympathetic Nervous System: Gets you ready for action, like a “go” signal.
    • Parasympathetic Nervous System: Helps you relax, like a “slow down” signal.

  • Balances Body Functions:

    • Keeps a balance between excitement and relaxation.

  • Important for Health:

    • A healthy autonomic system is crucial for overall well-being and functioning of the body.

Sympathetic & Parasympathetic Nervous System

Parasympathetic Nervous System (5.-9.):

  • “Rest and Digest” Response:
    • Promotes relaxation and recovery after stress.
    • Slows down heart rate, decreases blood pressure, and enhances digestion.
    • Helps the body return to a state of balance and conservation of energy.
  • Conservation Mode:
    • Allows the body to conserve and restore energy, essential for long-term well-being.

Sympathetic Nervous System (5.-9.):

  • “Fight or Flight” Response:
    • Prepares the body for action in challenging or dangerous situations.
    • Increases heart rate, breathing rate, and energy availability.
    • Redirects blood flow to muscles, preparing for physical exertion.
  • Quick Response:
    • Acts rapidly to mobilize the body’s resources for immediate action.

Summary

References

  1. Hainsworth,R. (1995).“The control and physiological importance of heart rate,” in Heart Rate Variability
  2. Marieb, E.N.,& Hoehn, K. (2013). Human Anatomy and Physiology
  3. Shaffer, F., McCraty, R., & Zerr, C. (2014). A healthy heart is not a metronome: an integrative review of the heart’s anatomy and heart rate variability
  4. Tortora, G.J., & Derrickson,B.H. (2014). Principles of Anatomy and Physiology
  5. Davis, A.M.,& Natelson, B.H. (1993). Brain-heart interactions. The neuro- cardiology of arrhythmia and sudden cardiac death
  6. Armour, J.A. (2003). Neurocardiology: Anatomical and Functional Principles 
  7. Kukanova, B., and Mravec, B. (2006). Complex intracardiac nervous system 
  8. Cameron, O.G. (2002). Visceral Sensory Neuroscience: Interoception 
  9. McCraty, R. (2011). Coherence: bridging personal, social and global health