riina scores every workout using heart rate data. The algorithm classifies effort zones, calculates time-in-zone distributions, and derives a point score that feeds into team leaderboards. Garbage HR signal in means garbage scores out. This page explains what makes a good HR source and lists the wearables we have tested and recommend.
Most wrist-worn wearables use photoplethysmography (PPG) — green LEDs that measure blood volume changes through the skin. PPG works well at rest and during steady-state cardio, but can struggle with motion artifacts during high-intensity or wrist-flexion-heavy activities like rowing or CrossFit.
Chest straps use electrical sensors (ECG-grade) that detect the heart's actual electrical impulses. They are largely immune to motion noise and deliver near-clinical accuracy across all intensity levels. For riina, this translates to more reliable zone classification and fairer scoring.
riina's AI scoring model ingests the full HR time series alongside your resting HR, max HR, and ventilatory thresholds. A wrist sensor that reads 20 BPM low during intervals will under-count Zone 4/5 time, costing you points. Conversely, a sensor that spikes erroneously can inflate scores unfairly. Either case undermines the competitive integrity of team games. The devices listed below are ones we have validated to produce clean, scorable signals across a range of workout types.
The links below are Amazon affiliate links. If you purchase through them, riina earns a small commission at no extra cost to you. We only recommend devices we have tested and validated with the riina scoring pipeline.
If you primarily do HIIT, CrossFit, rowing, or any workout involving rapid wrist movement, a chest strap like the Polar H10 will produce noticeably cleaner data. It pairs to your phone or watch via Bluetooth and the HR samples flow through to HealthKit or Health Connect the same way native wrist data does.
For steady-state running, cycling, or walking, modern optical sensors from Garmin, Apple, and Polar are accurate enough that you will not see a meaningful scoring difference versus a chest strap.
riina does not connect to wearables directly. It reads workout data from Apple HealthKit (iOS) and Android Health Connect. As long as your wearable syncs HR data to one of these platforms, it will work with riina. The devices on this page are the ones we have specifically validated for HR signal quality during real scored games.