Choosing the right heart rate monitor can be the difference between training smart and training blind. Whether you're logging 100km weeks on the bike or chasing a sub-40 minute 10K, accurate heart rate data is the foundation of every effective training plan. Two of the most popular options on the market right now are the Polar H10 Heart Rate Monitor — the gold-standard chest strap — and the COROS Heart Rate Monitor, an optical armband designed for athletes who want freedom of movement. So which one belongs in your kit bag?
The Case for a Chest Strap: Polar H10
The Polar H10 has earned its reputation through one thing above all else: accuracy. Using electrical impulse detection (ECG-based sensing) rather than optical light sensors, the H10 reads your heart's electrical signal directly — the same method used in medical-grade equipment. For interval training, HIIT sessions, and any workout where your heart rate spikes and drops rapidly, this matters enormously.
Key Specs — Polar H10
- Sensor type: ECG (electrocardiogram)
- Connectivity: Bluetooth 5.0 + ANT+
- Memory: Stores one training session onboard
- Battery life: Up to 400 hours
- Water resistance: 30m / IPX8 — swim-safe
- Compatibility: Polar Flow, Garmin, Wahoo, Zwift, most fitness apps
The dual Bluetooth + ANT+ connectivity makes the H10 the ultimate plug-and-play device for multi-device setups. Connecting simultaneously to your COROS Pace 3 or COROS Apex 2 watch AND a bike computer like the COROS Dura Solar is seamless. If you're a triathlete or multi-sport athlete, this versatility is invaluable.
The downside? A chest strap isn't for everyone. Some athletes find the strap uncomfortable for long efforts, or find it slips during high-sweat runs. It also requires a degree of skin contact to function, meaning it performs best when moistened slightly before use.
The Case for an Armband: COROS Heart Rate Monitor
The COROS Heart Rate Monitor takes a different approach. Worn on the upper arm, it uses optical PPG (photoplethysmography) sensors — the same technology used in most GPS sport watches — but positioned on the arm rather than the wrist, where blood flow is more stable and interference from wrist movement is eliminated.
Key Specs — COROS Heart Rate Monitor
- Sensor type: Optical PPG (upper arm)
- Connectivity: Bluetooth + ANT+
- Battery life: Up to 24 hours continuous
- Water resistance: IP67
- Compatibility: All COROS watches, Garmin, Zwift, and most ANT+/BLE devices
For runners especially, the COROS armband removes the chest-strap faff entirely. No gel, no tightening, no post-run strap marks. And because the upper arm sits closer to the brachial artery, it offers notably better optical accuracy than most wrist-based sensors — particularly during steady-state aerobic efforts.
Pair it with a COROS Pace Pro or COROS Apex 2 Pro and you have a clean, cable-free setup that's ideal for long trail runs, marathon training, and daily easy runs where comfort is king.
Accuracy Head-to-Head
Let's be direct: for raw accuracy — particularly during high-intensity intervals, sprints, and rapid heart rate changes — the Polar H10 wins. ECG-based sensing will always outperform optical sensors when it comes to transient spikes and drops in heart rate. If you're doing VO2 max intervals, threshold sessions, or Zwift racing, you want the H10.
For steady-state efforts — easy runs, long rides, Z2 aerobic base building — the COROS Heart Rate Monitor performs very well and the accuracy gap narrows considerably. For many athletes training predominantly in lower zones, the COROS will be more than sufficient.
Comfort & Wearability
The COROS armband takes this category. It's lighter, easier to put on, and many athletes forget it's there after a few minutes. The Polar H10 strap, while redesigned with a softer textile electrode, can still cause chafing on very long efforts and requires proper positioning every session.
Connectivity & Ecosystem
Both devices support Bluetooth and ANT+, meaning they'll pair with almost any modern GPS watch, bike computer, or training app. That said, the Polar H10's ability to connect to two Bluetooth devices simultaneously gives it an edge for athletes using multiple devices. The COROS armband integrates particularly well within the COROS ecosystem, especially for athletes already running a COROS watch.
Building out a full performance tracking setup? Take a look at our Train Smarter Kit Pro — Polar Edition or the Endurance Training Bundle — COROS Edition for complete ready-to-go training kits.
Which Should You Buy?
Here's our honest breakdown:
- Choose the Polar H10 if you do high-intensity training, intervals, or multi-sport racing and need the most accurate real-time heart rate data available. Also the better pick for swimmers.
- Choose the COROS Heart Rate Monitor if you prioritise comfort, train primarily in aerobic zones, and are already embedded in the COROS ecosystem.
- Own both? You're not alone — many serious athletes use a chest strap for hard sessions and an armband for easy days.
Whatever you choose, training with accurate heart rate data will transform how you approach your fitness. Explore our full range of heart rate monitors and GPS sport watches at North Sports, or build your perfect kit with one of our curated Performance Tracking Bundles.
Not sure which GPS watch pairs best with your new heart rate monitor? Our team is here to help — get in touch or browse our full wearables range.
