Netrin Coaching Team
Regular physical exercise is an effective strategy for improving health and quality of life. On the other hand, increasing sedentary rates and the associated increase in diseases such as obesity, highlights that there is still a need for identifying effective methods to prescribe exercise.
The main principles of exercise prescription that are extensively used include intensity, duration, frequency and mode (type) of exercise. The ability to successfully quantify training intensity is essential in determining the effect (adaptation) of a given exercise plan.
Intensity can be described using an external measure/load (e.g., pace, weight, velocity, etc), or an internal measure/load (e.g., heart rate, RPE, blood lactate, etc). Internal training intensity better reflects the physiological response that drives adaptations within our body.
Benefits of measuring HR
Measuring heart rate (HR) offers a practical, portable and non-invasive method of quantifying internal training intensity because HR increases along with exercise intensity.
What are HR zones?
A heart rate zone is a specific heart rate range, measured in beats per minute, that is used for monitoring training intensity during exercise. Zone based training can help you progress gradually toward your goals (not doing too much too soon), and improve fitness when used properly. Commonly 5 heart rate zones are considered during training, ranging from Zone 1 to Zone 5.
Heart rate zones will vary from person to person, based on his/her maximum heart rate (MHR). These zones are sometimes also represented by different colours and at Netrin we use the following colour codes to make it easy for you to associate with what intensity you should be training at on a particular day.
How do I calculate these zones?
Commonly, heart rate zones are calculated based on a percentage of your MHR. It is the highest number of beats per minute that the heart can pump blood under maximal stress. Primarily for safety reasons and lack of testing facilities, this number is generally not measured through maximal fitness testing, but rather through a simple calculation and is called estimated MHR.
At Netrin, we use the formula [210 - (0.65 * age)] to calculate thes estimated MHR at the start of the training journey. A percentage of this MHR represents the Target heart rate (THR) that you should be exercising at to gain different types of adaptations based on your fitness level and goals.
Each of us have unique physiological differences meaning that our ideal heart rate zones may vary. Factors such as fitness level, gender, training history, medical history and genetics can all play a role. Hence at Netrin we regularly assess and adjust training zones as needed to fine-tune each workout, ensuring training sessions remain challenging but sustainable without hitting a plateau.
Heart Rate Zones and Their Training Benefits
Let’s take a closer look at the different heart rate zones, w.r.t. what training in those zones should feel like and individual benefits .
HR Zones | % of MHR | Effort Rating | Benefits |
Zone 1 | 50 - 60% | Very easy - no sensation of effort in your legs, easy breathing and be able to maintain a long one-sided conversation without needing to take in deep breaths |
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Zone 2 | 60 - 70% | Easy - should feel pretty easy, at least in the beginning, but you should feel as though you have to work if you exercise in this HR zone for several hours |
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Zone 3 | 70–80% | Medium - you can sustain it for longer periods but would need to periodically pause to take a breathe during a conversation |
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Zone 4 | 80–90% | Hard - can sustain it for a limited time (20-60 minutes), conversation is difficult but not impossible |
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Zone 5 | 90 - 100% | Hardest - can sustain only for a short burst of time (2 - 5 minutes) and conversation is impossible |
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Periodizing your training with HR zones
Periodization stays the mainframe in developing an exercise program and HR zone-based periodization can be easily tailored to individual fitness levels and goals. By adjusting the duration and intensity of time spent in each zone we can create personalized training plans that target specific energy systems and physiological adaptations at different points in the training cycle.
Periodization allows us to focus on building stamina and endurance using zones 1 to 3, speed and power with zones 4 and 5, and recovery with zone 1 at the right times, leading to a steady, well-rounded progress.
Accuracy - key to maximizing the benefits of each HR zone
To gain benefits from each HR zone, it is essential to ensure that you are able to capture your heart beats accurately. Smartwatches and armbands provide convenience, but ECG-based sensors offer superior accuracy, reliability, and real-time responsiveness, especially for those tracking heart health and focused on improving cardiovascular fitness.
Why ECG sensors are more accurate
Feature | Smartwatches & Armbands (PPG) | ECG-Based Sensors |
Technology | Optical (LED-based) | Electrical (measures heart signals directly) |
Placement | Wrist or upper arm (prone to movement interference) | Chest or direct skin contact (stable signal) |
Response Time | Slight delay in tracking rapid heart rate changes | Instant response to heartbeats |
Skin Interference | Can be less accurate on dark skin, or on tattoos | Works for all skin types |
Overall Accuracy | Moderate | High (Medical-grade) |
Realtime Guidance and periodization of your training
Most devices, especially smartwatches only display heart rate zone ranges, leaving you to interpret the data yourself. Some offer basic alerts (e.g., vibrations when leaving a zone) but don’t tell you how to adjust your workout to stay in the desired HR zone, neither do they guide you on when and why you should train in a particular HR zone. This results in a passive tracking of your training without any practical, realtime guidance based on your goal, fitness level, workout type, or long-term progress.
Additionly, as your heart becomes stronger and more efficient along with improvements in your resting HR and heart rate varaibility (HRV) your HR zones should change. A true fitness-based HR zone adjustment factors in multiple performance indicators. Smartwatches don’t track this well, and generally rely on static formulas leading to inaccurate training zones over time. This results in the user left to figure out how to adjust their intensity based on general ranges, which isn’t as effective for personalized improvement.
The Netrin solution
At Netrin, we use a clinical grade ECG based sensor that measures the heart’s electrical signals directly, to provide more accurate and reliable data than many optical-based heart rate monitors, ensuring we get precise feedback during exercise.
Heart beats from the sensor are transmitted to the Netrin Enhance app in real-time. This allows the app to track how your heart rate fluctuates during exercise and actively interacts with you to deliver instant feedback on your training. If your heart rate moves too high or too low from the target zone, the app proactively gives you adaptive prompts to guide your pace (just as if a coach is guiding you). For example, it may tell you to slow down or pick up speed to get back into the optimal HR range for achieving the session training goal.
The biofeedback based audiovisual cues allows for targeted training, i.e. it helps you train the specific energy systems you want to improve—whether it’s building endurance, improving speed, or increasing power—by staying in the optimal zone for that goal.
For those new to exercise, the adaptive prompts helps ensure they don’t overdo it, making workouts safe and takes the guesswork out of training. The real-time coaching aspect also increases motivation by providing a sense of accomplishment every time you stay within your target zone or adjust your pace accordingly. The Guided Training feature is part of a broader training ecosystem that helps you set, track, and achieve goals through personalized workouts.
With improvements in fitness and physiological metrics, at Netrin the HR zones are dynamically changed ensuring that training intensity remains personalized and effective.
Master your zones, master your fitness
Now that you understand the power of heart rate zone training, why not give it a try to have a more targeted approach to your workouts? Connect with us now and see how guided workouts can transform your fitness journey!
For those already training using HR zones, please do share your experiences in the comments and let us know how heart rate training has shaped your fitness journey.
References
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Nimmerichter A, Eston RG, Bachl N, Williams C. Longitudinal monitoring of power 398 output and heart rate profiles in elite cyclists. Journal of Sports Sciences. 2011/05/01 399 2011;29(8):831-839.
Pilar Martín-Escudero, Ana María Cabanas, María Luisa Dotor-Castilla, et al. Are Activity Wrist-Worn Devices Accurate for Determining Heart Rate during Intense Exercise? Bioengineering (Basel). 2023 Feb 15;10(2):254
Daniel Koerber, Shawn Khan, Tahmina Shamsheri, et al. Accuracy of Heart Rate Measurement with Wrist-Worn Wearable Devices in Various Skin Tones: a Systematic Review. J Racial Ethn Health Disparities. 2022 Nov 14:1–9
Dustin T. Weiler, Dustin T. Weiler, et al. Wearable Heart Rate Monitor Technology Accuracy in Research: A Comparative Study Between PPG and ECG Technology. September 2017Proceedings of the Human Factors and Ergonomics Society Annual Meeting 61(1):1292-1296
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