Is a chest strap more accurate than a wrist heart rate monitor?
Yes, chest straps are significantly more accurate than wrist-based optical heart rate monitors, especially during intervals and variable-intensity training. Wrist monitors can lag 20-30 seconds and miss sharp spikes. For serious zone-based training, use a chest strap like Polar H10 or Garmin HRM-Pro.
Optical wrist-based heart rate sensors (the green LEDs on modern Garmin, Apple, Coros watches) work by measuring blood volume changes through the skin. They've improved dramatically but still have fundamental limitations — they lag behind real HR by 10-30 seconds, struggle during rapid changes (intervals), can be thrown off by wrist cadence matching your arm swing, and are affected by cold weather, skin tone, and tattoos. For steady easy runs, wrist HR is usually within 5-10 bpm of real HR — fine for rough zone training. For intervals, tempo transitions, or any session where heart rate changes quickly, wrist monitors commonly miss the actual peak by 20-30 bpm and lag by 30+ seconds. Chest straps (Polar H10, Garmin HRM-Pro, Wahoo Tickr) measure electrical signals directly from the heart, giving near-real-time accuracy comparable to medical ECGs. They're the gold standard for serious training. Costs: chest straps are 5,000-12,000 INR and pair with any running watch or phone via Bluetooth/ANT+. If you're doing heart-rate zone training, lactate threshold testing, or relying on HR for pacing decisions, a chest strap is essential. If you just want general fitness tracking, wrist HR is fine. The Polar H10 is widely considered the most accurate chest strap, with 6-7 year lifespan and replaceable battery.