Heart rate training for runners isn’t new, but wearable technology and analysis tools continue to evolve.
While the first portable heart rate monitors were introduced in the early 1980s, GPS watches became available only in the 2000s. Ever since, this duo has revolutionized how we plan, monitor, and analyze endurance training, as intensity could now be plotted against pace. That means we now have quantitative data for performance improvements.
However, to get the most out of heart rate training, you need to be familiar with the latest hardware, software, and exercise science — all of which will be covered in this article.
Pace Training vs Heart Rate Training
There are good arguments for both pace-based training and heart rate training. That’s why both metrics should be displayed on the first screen of your smartwatch. But you need to set one metric as the default, as pace-based training and heart rate training don’t overlap. Therefore, I recommend setting your training plan as a default by pace, but keep an eye on your heart rate for anomalies such as training readiness, undulating terrain, and hot summer days.
Training by Pace
- Goal-oriented and race-specific
- Clear and quantifiable progress
- Ideal for interval workouts
Training by Heart Rate
- Tracks aerobic fitness improvements
- Adjusts for the body’s daily readiness
- Adjusts for external conditions
Heart Rate Training Zones
Once you have determined your heart rate reserve, you can calculate your training zones.
Low-Aerobic (Zone 1 + 2)
Low-end aerobic training is training zones 1 and 2. While zone 1 training are recovery runs, zone 2 training are your typical easy runs. Both intensities recruit only slow-twitch muscle fibers. The only exception is in the long run, where some fast-twitch fibers are activated once the endurance fibers are fatigued.
High-Aerobic (Zone 3)
The high-end aerobic training zone includes all intensities between the aerobic threshold (LT1) and the anaerobic threshold (LT2). Here, lactate starts to rise above baseline but your body is still able to metabolize lactate faster than it is produced. That represents 2 – 1 hour race pace, or 30K – 15K pace for intermediate and advanced runners.
Anaerobic (Zone 4 + 5)
All paces faster than your lactate threshold (~1-hour race pace) have a significant anaerobic contribution, causing lactate to accumulate faster than it can be metabolized. That means 10K race pace and faster depend on the anaerobic system to some degree, even though the aerobic system supplies most of the required energy in training zone 4.
For paces beyond VO2 max (2-1 mile pace), heart rate is no longer a suitable indicator for two reasons: First, any effort beyond HRmax comes from the anaerobic system, as the aerobic system is already maxed out. Second, the repetitions are so short that the heart rate doesn’t accurately reflect this effort due to the heart rate lag.
Calculate Your Heart Rate Reserve
Now that we know the training zones, we need to personalize them for you. There are two ways to calculate your heart rate zones: the percentage of your maximum heart rate (%HRmax) and the percentage of your heart rate reserve (%HRR).
Percentage of Maximum Heart Rate (%HRmax)
The most common formula for calculating training intensities is to determine a percentage of your maximum heart rate (HRmax). However, it’s also prone to error because it doesn’t take your resting heart rate into account, which can vary by 20-30 beats, even among runners of similar ability. The only reason it’s still being used is because of its simplicity.
Percentage of Heart Rate Reserve (%HRR)
The gold standard for endurance training is setting up your heart rate zones based on your heart rate reserve (HRR). It is the difference between your maximum heart rate (MHR) and your resting heart rate (RHR). For example, if your maximal heart rate is 185 bpm and your morning resting heart rate is 45 bpm, your heart rate reserve is 140 bpm (185 bpm – 45 bpm).
Target heart rate = ((HRmax – RHR) x % intensity) + RHR.
Tools You Need for Heart Rate Training
To get the most out of heart rate training, you’ll need a few essential tools. These devices and apps help ensure your data is accurate, actionable, and easy to track over time.
GPS Running Watch
GPS and heart rate tracking are now standard features on most entry-level running watches. Higher-priced models include a plethora of additional functionalities, but the real power of any watch lies in its ability to display your pace and heart rate in real time. That’s essential. For serious runners, I recommend a heart rate chest strap. Although wrist-based heart rate monitoring has evolved, a chest strap remains the gold standard, as it provides greater accuracy.
Online Training Log
Online training logs, such as FinalSurge and TrainingPeaks, go beyond simple workout tracking. These platforms overlay heart rate with elevation, pace, cadence, and power (if available). This makes it easy to see how your aerobic fitness is progressing or spot signs of fatigue. If you work with an online running coach, both FinalSurge and TrainingPeaks allow real-time coach access to your workouts and heart rate data. That way, your coach can provide feedback on your workouts and make informed adjustments.
Resting Heart Rate and Heart Rate Variability
Training zones aside, there are two more metrics worth paying attention to as an endurance athlete: resting heart rate (RHR) and heart rate variability (HRV). Both are valuable tools for different reasons.
Resting heart rate (RHR)
Your resting heart rate is a long-term performance metric, not a daily indicator of training readiness. It won’t fluctuate as quickly or dramatically as heart rate variability, but over weeks and months, a consistently lower RHR can reflect gains in aerobic fitness, while a plateau or upward drift indicates stagnation or an excessive training load. However, a change in resting heart rate is less likely for advanced runners whose improvements often stem from superior running economy.
Heart Rate Variability (HRV)
Your heart rate variability, by contrast, provides insight into your immediate training readiness. It measures the subtle fluctuations in time between individual heartbeats, thereby reflecting the balance and responsiveness of your autonomic nervous system. HRV is far more sensitive to day-to-day changes than RHR and can be influenced by factors such as sleep, training load, mental stress, illness, and even travel.
If you have a high-end smartwatch with an optical HR sensor, consider wearing it 24/7 for continuous tracking of your RHR and HRV.
