Waterproof Heart Rate Strap Buying Guide: Garmin HRM-Tri vs Polar H10 Swimming Accuracy Review

Introduction

Swimming is one of the most difficult activities for heart rate monitoring among all endurance sports. Wrist-based optical heart rate (OHR) sensors suffer a significant drop in accuracy during swimming due to water interference and frequent wrist movement—a problem many runners only discover after transitioning to triathlon. While chest strap heart rate monitors are accurate, brand design differences are significant when it comes to stable operation in a swimming environment. This article focuses on the real-world swimming performance of two mainstream waterproof heart rate straps on the market: the Garmin HRM-Tri and the Polar H10.

Basic Specifications Comparison

Specification	Garmin HRM-Tri	Polar H10
Water Resistance	5 ATM (50 m)	IPX7 (30 min/1 m)
Swimming Data Storage	Built-in memory, syncs after swim	Real-time transmission (requires paired device)
Connectivity	ANT+ (during swimming), Bluetooth (sync on land)	Bluetooth 5.0 + ANT+
Battery Life	Approximately 10 hours	Approximately 400 hours (replaceable battery)
Battery Design	Rechargeable	CR2025 replaceable
Swimming Heart Rate Accuracy	★★★★★	★★★★☆
Taiwan Price	NT$3,500–4,500	NT$2,800–3,800
Device Compatibility	Best with Garmin watches, partial third-party support	Broad compatibility with multi-brand watches and phones

Garmin HRM-Tri In-Depth Review

Core Design Advantages

The biggest feature of the Garmin HRM-Tri is built-in memory. Since ANT+ signals cannot penetrate water during swimming, Garmin’s solution is to store heart rate data directly on the strap itself, then automatically sync it once you approach your watch after the swim. This means that even if the watch cannot display heart rate in real time during swimming, you can still analyze complete swimming heart rate data afterward.

Swimming Accuracy

• Pool Swimming: Excellent—the built-in accelerometer helps identify strokes, and heart rate data is complete with a delay of under 5 seconds (after syncing)
• Open Water: Equally accurate, but it is recommended to ensure a snug fit of the chest strap; salt from seawater and sweat does not affect electrode function
• High-Intensity Intervals: Sensitive peak heart rate capture, accurately recording maximum heart rate during sprint segments

Usage Notes

• The snugness of the elastic chest strap directly affects heart rate accuracy; confirm it fits properly before each use
• After prolonged use, conductive electrodes may accumulate dead skin cells and affect the signal; clean them regularly
• Full functionality requires pairing with a Garmin device; some features may not work with other brand watches

Polar H10 In-Depth Review

Core Design Advantages

The Polar H10’s advantage lies in its broad Bluetooth compatibility, connecting to nearly all training apps that support heart rate straps (including Garmin Connect, Wahoo, Strava, Zwift, etc.), and it can connect to two Bluetooth devices simultaneously. The replaceable battery design lowers long-term usage costs.

Swimming Accuracy

• Pool Swimming: Requires a device with swimming heart rate strap reception capability, such as the Polar Vantage V2, Suunto, etc., or use the swimming mode in the Polar Beat App
• Open Water: Bluetooth does not penetrate the water surface; a paired watch with a swimming mode is recommended
• High-Intensity Training: Excellent electrode quality, accurately capturing heart rate across the range from resting to maximum

Usage Notes

• If the watch cannot receive data in real time during swimming, post-swim syncing depends on the level of support from the paired device
• Bluetooth 5.0 delivers excellent real-time connectivity above the water surface, ideal for displaying heart rate during running and cycling

How to Choose

Choose the Garmin HRM-Tri if you:

• Use a Garmin watch (Forerunner, Fenix, Instinct series)
• Value the completeness of swimming heart rate data and post-analysis
• Compete in triathlons and need full recording across swim → bike → run

Choose the Polar H10 if you:

• Use Polar, Suunto, or other brand devices
• Have multi-device needs (watch + phone app connected simultaneously)
• Prefer a replaceable battery design and don’t want to worry about charging when traveling abroad for races

Chest Strap Comfort Comparison

• Strap Width: Garmin is slightly narrower; Polar is slightly wider, with slightly less pressure felt during extended wear on the Polar
• Strap Material: Both use soft materials; long-distance triathletes report no significant discomfort after wearing either for 3–4 hours or more
• Sensitive Skin: Some people experience mild irritation from the electrode pad material; Polar offers more accessory options

Conclusion

For swimmers within the Garmin ecosystem, the HRM-Tri’s built-in memory is a killer feature, eliminating the blind spot in swimming heart rate data. The Polar H10, with its broad compatibility and durable replaceable battery design, becomes the best choice for multi-device users. If you’re buying just one heart rate strap for full triathlon use, the HRM-Tri offers more complete feature integration; if your primary focus is swimming heart rate monitoring but you also run and cycle, the H10 offers greater flexibility.

Related Reading

• Heart Rate Monitoring for Swim Training: Effective Ways to Use a Waterproof Heart Rate Strap
• Running Heart Rate Monitoring: In-Depth Accuracy Comparison Between Heart Rate Straps and Optical Sensors
• Heart Rate Strap vs Optical Sensor Review: Polar H10 vs Garmin HRM-Pro vs Apple Watch Accuracy
• Heart Rate Strap vs Optical Watch: Which Wins in Heart Rate Monitoring Accuracy?