Why Power Zone Training Reduces Your Resting Heart Rate

In a recent forum post, I came across a member’s query regarding a potential decrease in their Resting Heart Rate (RHR). Let me provide you with a brief explanation of how effective training can impact RHR.

Our body requires a specific amount of blood supply to function at any level of exertion. This blood supply delivers essential nutrients to our cells and removes waste products. The quantity of blood flow pumped by our heart at any given moment is known as Cardiac Output (CO). Generally, CO ranges from approximately 4 liters per minute to around 28 liters per minute, depending on the body’s requirements. This means that during periods of maximum demand, our heart can increase its output by about sevenfold. This increase demonstrates that our heart’s output is influenced by our level of exertion. Factors such as illness, injury, and over-training can also lead to an increased demand for blood supply without necessarily exerting ourselves physically. In such cases, our Cardiac Output may increase without a corresponding rise in our heart rate. The remaining increase in output is primarily caused by heightened contractility, which refers to the power with which our heart squeezes.

However, for the purpose of discussing RHR specifically, let’s set aside the complexities of exercise-level heart function for another conversation.

Cardiac Output comprises two main components: heart rate and contractility. Heart rate can be loosely compared to the cadence in cycling, as alterations in either can affect the overall output. On the other hand, contractility, which measures how forcefully the heart contracts, can be likened to resistance, with changes in contractility also influencing the output.

The heart rate is responsive to the levels of waste products present in our bloodstream. Many individuals have observed that their heart rate tends to fall within a specific range corresponding to each Power Zone they engage in during their cycling sessions. When we exert a certain wattage output on the bike, our body produces a particular amount of waste product known as lactate, which needs to be eliminated through buffering. If the amount of lactate increases, our body reacts by increasing the cardiac output to enhance the supply of fresh blood.

Peloton Power Zone training has a direct impact on the efficiency of our heart. Here’s a breakdown of what occurs:

  • Endurance-focused training in Zones 2-4 leads to an enlargement of the chambers in our heart, including the atria and ventricles. This expansion allows these chambers to accommodate a greater volume of blood. Consequently, with each heartbeat, more blood can be pumped. As long as the muscular walls of the heart strengthen proportionately, this enlargement of the chambers is advantageous. (*Get ready for an insightful moment about special PZ training!)
  • Power-oriented PZ training, particularly in Zones 6 and 7, requires the heart to exert more force to counteract the elevated blood pressure resulting from intense exertion. Visualize a weightlifter straining to complete a heavy lift: the blood pressure in their aorta surges, and their heart must exert greater effort to push blood against this resistance. These high-resistance endeavors cause the heart muscle to thicken and strengthen, much like how bicep curls contribute to the growth of our biceps muscles, and so on.

Consequently, we are left with a heart that possesses a larger capacity for single-stroke volume and greater muscular strength!

During periods of rest, our body requires a minimal yet essential amount of blood flow. With our heart now being slightly larger and stronger, we require fewer beats to meet this demand. As a result, there is a reduction in heart rate not only during rest but also at other levels of exertion. We adjust our “idle” speed accordingly. For instance, what used to take 60-70 beats per minute may now only require 50 beats.

While I have glossed over certain details, this is essentially how it functions!

Now, let’s explore why engaging in various types of Power Zone rides is crucial:

  • If we solely focus on endurance rides at lower levels of exertion, our heart chambers enlarge; however, the muscle stretches without the corresponding increase in strength obtained from high-exertion workouts. A large, flabby heart is not desirable.
  • Conversely, if we solely engage in high-exertion workouts, the chambers do not enlarge as much, but the muscular walls become thicker. This process limits the amount of blood pumped in a single beat since it becomes more challenging to stretch the chamber and fill it with blood for pumping.

Therefore, the combination of different Power Zone ride types is strategically designed to yield the most effective training stimulus for heart development. Now, the “secret benefit” of PZ TRAINING is unveiled. This is why I am passionate about assisting others in comprehending and maximizing this process.

If you are still wide awake after reading this, it must be due to the incredible Power Zone heart that enables you to stay alert! 😂

Learn more about the Peloton FTP test and why it’s important.

This article is part of an ongoing series on Power Zone Training. You can find the other entries below in suggested reading order:
#1 – What is Peloton Power Zone Training?
#2 – Peloton FTP Test Strategies & Lessons
#3 – Peloton Power Zone Training – My Zones Are Too Easy!
#4 – Living with new zones & more FTP test
#5 – Post Peloton FTP Test New Zone Struggles (Mental & Physical)
#6 – Decreases in Peloton FTP
#7 – Age-related limitation & degradation of FTP in Power Zone Training
#9 – Resting Heart Rate: Why Power Zone Training reduces it (This article)
#10 – The “Training Effect”


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