Zephyr makes some interesting bio-logging products. Their harness tracks “medical-grade ECG, as well as heart rate, breathing rate, and 3-axis accelerometery.” You can also use a shirt, and add an optional GPS. Here’s what they say about their shirts:
Zephyr’s Team BioHarness 3 Compression Shirts were designed specifically for the BioHarness system. Available in a variety of sizes, these shirts are uniquely designed to make connecting your BioHarness a snap! Simply pop the sensor directly into the chest receptacle.
The Team Compression Shirts currently support the following measurements: – Heart Rate – Heart Rate Recovery – Heart Rate Variability – Accelerometry – Intensity & Load – GPS Sensors (GPS Receiver sold separately)
Note:Respiration is currently not supported by the Team Compression Shirt. If you need support for Respiration measurement, take a look at the BioHarness 3 Side Strap!