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As heart-rate tracking technology improves, it’s important to adjust how we use it in our training. Wrist-worn, optical heart-rate sensors offer convenience, but they aren’t perfect. Understanding their limitations—and how to use the data effectively—is key to benefiting from these metrics without getting overwhelmed by them.

Starla Garcia, a 31-year-old runner, found that her Garmin Forerunner 235 often gave her inflated heart-rate readings during easy runs. While external factors like temperature can influence heart rate, research shows that Garcia isn’t alone in experiencing these inaccuracies. A 2017 study revealed that wrist-worn devices were less accurate for certain groups, including men, people with darker skin tones, and those with higher body mass indexes. Environmental factors like altitude and weather conditions can also distort heart-rate readings, according to Neal Henderson, head of sports science at Wahoo Fitness.

So, while tracking heart rate with a wrist device is certainly convenient, it may not be the most reliable way to guide your training. To better understand this, we need to look at how these devices actually work.

How Heart-Rate Tracking Devices Work

There are two primary types of heart-rate monitors: chest straps and wrist-based devices. Chest straps typically measure electrical conductivity in the heart, while wrist and arm devices measure blood flow using optical sensors.

Wrist devices use a method called photoplethysmography (PPG), which detects changes in blood flow. Since blood absorbs green light and reflects red light, optical sensors in these devices emit green light to detect blood flow in the wrist. The more blood flow there is, the more green light is absorbed, allowing the device to calculate heart rate based on these fluctuations.

While this method works fairly well, it’s not as accurate as chest straps. A 2017 study in JAMA Cardiology showed that wrist-based devices often provide less accurate readings than chest straps, especially during exercise. The accuracy of the Apple Watch was better compared to some other wrist-worn devices, but it still fell short of a chest strap.

Similarly, a 2019 study confirmed that chest straps, like the Polar H7, were the closest in accuracy to an electrocardiogram (ECG), while wrist devices like the Apple Watch and Fitbit performed well, but not as accurately.

The Limitations of Wrist-Based Heart Rate Tracking

While wrist-based devices offer greater convenience, they have several drawbacks when it comes to accuracy. One major issue is that many runners rely on heart-rate data to establish training zones, often using maximum heart rate as a baseline. However, determining your max heart rate through a test can be challenging and even risky for some people, such as those new to exercise or with existing health conditions.

Additionally, wrist-based devices are not always effective for all demographics or activities. For example, optical sensors may struggle with darker skin tones or tattoos. High humidity, altitude, and biomechanical changes can also lead to inaccurate readings. Some research suggests that the green light used by these devices isn’t ideal for everyone due to its wavelength, which is more readily absorbed by melanin in darker skin tones.

Alternative Ways to Use Heart Rate Effectively

Despite the limitations of wrist-based heart-rate monitors, these devices can still be valuable tools for personalizing your training. The key is understanding the data, using it appropriately, and not letting it dictate every aspect of your workout.

Training

If you want to track heart-rate data for training purposes, using a chest strap will provide more reliable information. However, it’s essential to interpret this data alongside how your body feels. Running coach Kaitlin Goodman advises runners to trust their bodies. “If your watch says your heart rate is 180 and you feel comfortable, trust yourself,” she says.

Instead of focusing on max heart rate, some runners, like David Roche, prefer to use lactate threshold heart rate (the point at which lactate builds up faster than it can be cleared). This method helps determine the intensity of exercise and can provide more accurate training zones based on individual fitness levels.

Recovery

Heart-rate variability (HRV) is another useful metric for tracking recovery. Devices like Whoop measure HRV to gauge your overall recovery status. A higher HRV indicates better recovery. If your device doesn’t track HRV, you can monitor your resting heart rate (RHR), which is often measured accurately by wrist-based devices. Elevated RHR can be a sign that you need more rest.

Nutrition

Garcia, a registered dietitian, used heart-rate data to monitor her hydration and nutrition levels during training. After noticing discrepancies in her device’s readings, she switched to a chest strap, which gave her more accurate data. During Grandma’s Marathon, for example, Garcia used her heart rate readings to adjust her electrolyte intake based on how she felt, ultimately helping her maintain control over her performance despite rising temperatures.

Where Is Heart Rate Tracking Headed?

Heart-rate tracking technology is still evolving, and manufacturers are working hard to improve accuracy across all skin tones and demographics. Companies like Coros, Apple, and Garmin are investing in more inclusive and accurate optical heart-rate sensors.

Despite its current limitations, heart-rate tracking is a valuable tool when used with care. As Garcia’s experience shows, heart-rate data can help athletes fine-tune their training, recovery, and nutrition strategies. With continued improvements in technology, we can expect even more reliable and useful data to guide our running performance in the future.

Embarking on your running journey can be both exciting and challenging. Whether you’re aiming to build a healthy habit, get fit, or train for a race, this guide is designed to help you take the first step and gradually progress. Running may seem simple, but for beginners, it requires a methodical approach to avoid injuries and build long-lasting endurance. Here’s how you can start running today, no matter your fitness level.

Step 1: Get Motivated and Build a Habit

The first step to becoming a runner is motivation. The key to staying consistent is turning exercise into a habit. Once you make it a part of your routine, it won’t feel as difficult or require as much willpower. As Charles Duhigg, author of The Power of Habit, explains, a habit consists of a cue, routine, and reward. To build your running habit:

• Set a plan: Define your cues, such as a specific time or place to run, and pair them with a reward (like a post-run treat).
• Be consistent: Choose a regular time to run each day and stick to it. The more consistent you are, the more natural it will become.
• Reward yourself: After each run, reward yourself with something you enjoy. This creates a positive association with your runs.
• Create a support system: Running with a friend or joining a local running group can keep you accountable and motivated.

Step 2: Start Moving with Walking

Before jumping straight into running, it’s essential to get your body used to regular movement. Walking is the best place to start if you’re new to exercise. Aim for brisk walks—not leisurely ones—to prepare your body for the physical demands of running. Walking helps strengthen your muscles and joints, reducing the risk of injury when you eventually start running.

Here’s a simple walking plan to get you ready for running:

• First workout: 15-minute walk
• Goal workout: 60-minute walk

Note: If you’re new to exercise or have specific health concerns, consider extending this walking phase to 8-12 weeks to allow your body to adjust.

Step 3: Transition from Walking to Running

Now that you’re comfortable with regular walking, it’s time to add running into the mix. Start with a run/walk approach to gradually build your endurance. The goal here is to run for short intervals, followed by walking, and slowly increase the running duration.

Begin with a seven-week run-walk plan:

• Week 1: 30 minutes of walking
• Goal: 60 minutes with a 2:1 running to walking ratio by the end of the seven weeks.

If you feel ready to challenge yourself more, you can gradually adjust your run/walk intervals. But remember, it’s okay to repeat a week if you feel you need more time.

Step 4: Running Non-Stop

Once you’ve built up your stamina with run/walk intervals, you can work toward running continuously without stopping. The aim is to run at a conversational pace, so you should still be able to talk without gasping for air.

A simple 7-week beginner plan to help you run your first 5K:

• Week 1: 30 minutes, with 20 minutes at a run/walk ratio of 3:2
• Goal: Run 3.1 miles (5K) without stopping.

Before beginning this plan, ensure that you’ve spent at least 6 weeks run-walking, with around 30 minutes of exercise, five days a week. Adjust your pace and duration if needed, but aim to finish the 5K run within 14 weeks.

Step 5: Build Endurance for Longer Runs

Once you’ve mastered a non-stop 5K, it’s time to set your sights on longer distances. Increasing your endurance will allow you to run a 10K and prepare you for future races. This plan incorporates hills and some speedwork to build strength.

A 7-week plan to take you from a 5K to a 10K:

• Week 1: 2-mile run
• Goal: Run 6-7 miles continuously by the end of the plan.

If you’ve been running consistently for at least 30 minutes per session and can comfortably complete a 5K, you’re ready for this challenge. If it feels too fast, don’t hesitate to repeat any week until you’re ready to move on.

Step 6: Improve Your Speed

If you’ve been running for a while and are comfortable with 5-6 mile runs, it’s time to focus on speed. This plan will help you run faster, improve endurance, and build leg strength.

An 8-week plan to boost your running speed:

• Week 1: 2-mile easy run
• Goal: 8-mile run with 4×800 meters at your 5K pace.

This plan is for “advanced beginners,” so you should already be running around 18 miles per week, including a 5-mile long run. If you’re short on time, you can reduce the number of runs per week, but aim to keep up the intensity during your key workouts.

Tips for Success:

• Get a check-up: If you’re over 40 or have health concerns, consult with your doctor before starting any new exercise routine.
• Invest in good gear: A quality pair of running shoes and sweat-wicking socks are essential for preventing injuries.
• Sneak in activity: Take walking breaks throughout the day to stay active and keep your body ready for your running sessions.
• Set realistic goals: It’s important to stay consistent with your running while keeping a pace that feels comfortable. Speed will come with time.
• Stay flexible: If needed, split your runs into shorter sessions. Three 10-minute runs can offer the same benefits as one 30-minute run.
• Track your progress: Use a running log or an app to track your miles and monitor your improvements.
• Be patient: Results won’t come overnight, so trust the process. As your body adapts to running, you’ll notice physical and mental improvements.

Conclusion

Starting to run is a rewarding journey that will enhance your fitness and overall well-being. Whether you’re aiming to complete your first 5K or run a faster 10K, building a strong foundation and progressing gradually is key to achieving your goals. Keep a steady pace, stay consistent, and most importantly, enjoy the process of becoming a runner.