Triathlon Heart Rate Monitors

A heart rate monitor gives you real-time insight into your effort level during training and racing. For triathletes that is extra valuable: you train in three disciplines each with a different energy consumption and recovery demand. By measuring your heart rate you know whether you are training in the right zone, attacking too hard or staying below your potential.

Heart rate monitors are available as a chest strap or as a wrist sensor. A chest strap measures via ECG technology and is more accurate, especially at high intensity and interval training. A wrist sensor measures optically via your skin and is simpler to use but slightly less precise with rapid heart rate changes. For triathletes who want to measure all three disciplines, waterproofing and the connectivity of the device are also important criteria. The most important selection criteria are the type of measurement, the protocols for connection with watch and cycling computer, and whether the model is suitable for use in the water.

Which heart rate monitor suits you?

The right choice depends on which disciplines you want to measure, how precisely you want to train and which devices you already use. The following scenarios help you quickly find the right direction.

You want to measure your heart rate during all three disciplines, including swimming: Choose a waterproof chest strap with swim support or a heart rate monitor with an optical wrist sensor that also works in water. With a chest strap, pay attention to the waterproof rating: IP68 or an ATM value of at least 30 metres guarantees use during swimming. Some chest straps store heart rate in memory during swimming and synchronise the data afterwards with your watch.

You want the most accurate heart rate measurement with interval training and high intensity: Choose a chest strap. Optical wrist sensors struggle with rapid heart rate rises and falls during tough interval sets. A chest strap via ECG measurement responds faster and more accurately to heart rate changes, which is essential if you train based on zones and want to monitor limits.

You want to simultaneously transmit your heart rate to both your cycling computer and your sports watch: Choose a chest strap with both ANT+ and Bluetooth dual transmission. ANT+ is the standard protocol for cycling computers and can simultaneously send data to multiple devices. Bluetooth generally connects to one device at a time. A chest strap with both protocols simultaneously gives you the most flexibility for a triathlon setup.

You want to start with heart rate training and are looking for a simple entry: A wrist sensor integrated in a sports watch or a simple chest strap with Bluetooth and an accompanying app is the lowest-threshold way to start. You do not need to pair separate devices and immediately have insight into your heart rate and zones via your phone or watch.

What to look for when purchasing?

Chest strap or wrist sensor

A chest strap measures your heart rate via electrical signals from your heart, comparable to an ECG. That gives an accurate and fast-responding measurement, even at high intensity. A wrist sensor measures optically via blood flow under the skin and is less accurate with rapid heart rate changes or in cold water. For serious triathlon training and interval work a chest strap is the better choice. For daily endurance training and general insight a wrist sensor is sufficient for most athletes.

ANT+ and Bluetooth connectivity

Most modern heart rate monitors support ANT+, Bluetooth or both. ANT+ is the most used protocol for sports equipment: it can simultaneously connect with multiple devices and has a stable connection during movement. Bluetooth is more widely available and works well for connection with a smartphone. For triathletes who use a cycling computer and a sports watch, a model with dual ANT+/Bluetooth is the most practical choice, so that both devices simultaneously receive data.

Waterproofing

If you plan to use the heart rate monitor during swimming too, check the waterproof rating. An IP68 certification or an ATM value of at least 30 metres is the minimum for swim use. Keep in mind that not all chest straps offer swim support: some are water-resistant for rain and sweat but not suitable for submersion. Also check whether the chest strap stores heart rate in internal memory during swimming or whether the connection is interrupted as soon as you go under water.

Heart rate zones

Most heart rate monitors work with five zones based on your maximum heart rate. Zone 1 and 2 are light to moderate effort, ideal for base fitness and recovery. Zone 3 is the tempo range. Zone 4 and 5 are high intensity and maximum effort, for interval training and race pacing. The more accurately you know your personal maximum heart rate, the more reliable the zones are. A heart rate monitor with automatic zone determination or connection to a training app helps you set up and monitor the zones well.

Fit and wearing comfort

A chest strap must fit well against your skin for a reliable signal, but must not constrict. Too loose gives noisy readings; too tight is uncomfortable during longer training sessions. Make sure the chest strap is damp before you put it on for better conductivity. Wrist sensors in watches are more comfortable in daily use but must sit firmly enough to deliver accurate measurements, even during movement.

Our advice: Choose a chest strap with ANT+ and Bluetooth dual support if you train with both a cycling computer and a sports watch. That is the most versatile option for triathlon training and prevents you being forced to choose which device receives the heart rate. Do you already have a sports watch with integrated wrist sensor? Then an external chest strap adds accuracy at high intensity without having to purchase a new watch.

Heart rate monitor or sports watch with built-in sensor?

Many modern sports watches have an integrated optical heart rate monitor on the wrist side. That is handy for daily use and endurance training. The limitations are the already mentioned accuracy at high intensity and the limited waterproofing of some models for swimming.

A separate chest strap is more accurate, waterproof and transmits data to your existing watch or cycling computer without having to buy a new watch. For triathletes who already have a good sports watch, a separate chest strap is therefore a cost-efficient way to improve measurement quality without leaving the familiar environment of their existing device.

Who are triathlon heart rate monitors suitable for?

• Triathletes who want to train structurally based on heart rate zones across all three disciplines.
• Athletes who want to accurately dose their training intensity for better performance and less overtraining.
• Beginners who want to start with heart rate training for the first time and want insight into their effort level.
• Advanced triathletes who want to expand their existing sports watch or cycling computer with more accurate heart rate data via an external chest strap.

A separate heart rate monitor is less necessary if your sports watch already has an accurate integrated wrist sensor and you mainly train at low to moderate intensity. In that case the integrated sensor delivers sufficiently accurate data for most training sessions.

Need help with your choice?

Would you like to buy a heart rate monitor but are not sure which type suits your training setup best? Then we are happy to help. You can reach our specialists by phone on +31 (0)413-256800, send an email or visit our triathlon store in Volkel, the Netherlands.

Frequently asked questions about heart rate monitors for triathlon

What is the difference between a chest strap and a wrist sensor?

A chest strap measures heart rate via electrical signals from the heart, comparable to an ECG. That delivers an accurate and fast-responding measurement, even at high intensity and rapid heart rate changes. A wrist sensor measures optically via blood flow under the skin. That is less accurate with intensive interval training or in cold water, but simpler to use for daily endurance training. For serious triathlon training and interval work, a chest strap is the better choice.

Can I use a heart rate monitor during swimming?

That depends on the model. Not all chest straps are suitable for use in the water. Check the waterproof rating: IP68 or at least 30 metres ATM is required for swim use. Some chest straps fully support swimming and store heart rate in internal memory during the swim set, which you synchronise afterwards with your watch. Other models are water-resistant for rain and sweat but not intended for submersion.

What is ANT+ and why is it important for triathletes?

ANT+ is a wireless communication protocol widely used in sports equipment. It can simultaneously connect with multiple receivers, such as a cycling computer and a sports watch at the same time. That is specifically valuable for triathletes: you can simultaneously receive heart rate on your cycling computer on the handlebars and your wrist watch, without having to choose. Bluetooth is more widely available but in most cases connects to only one device at a time.

What are heart rate zones and how do I use them?

Heart rate zones are ranges of your heart rate expressed as a percentage of your maximum heart rate, divided into five zones from recovery and light effort (zone 1-2) to high intensity and maximum effort (zone 4-5). By dosing your training based on zones you train more specifically: zone 2 builds aerobic endurance, zone 4-5 improves threshold values and peak performances. A heart rate monitor makes zones visible in real-time, so that you do not attack too hard in endurance training or are too cautious in interval blocks.

How accurate is a wrist sensor with triathlon training?

A wrist sensor is sufficiently accurate for endurance training at moderate intensity. At high intensity, interval training or in cold water the accuracy decreases because optical sensors struggle with rapid heart rate changes and with reduced blood circulation at the wrist surface. For triathletes who train on accurate zones at high intensity, a chest strap is a better addition to or replacement of the wrist sensor.