Hot on the heels of the addition of the Explore tile, an update to the Microsoft Health application overnight brought with it a software update to the Band 2 accessory, adding in colour-coded heart icons according to the 'heart rate zone' that you're working out in. A nice touch (though I've yet to get anywhere near a high enough rate to trigger it!) for the young at heart - literally!

The changelog is via the message on the Band 2 itself:

Track your heart rate zones on Band: Improve your workout health with notifications for heart rate zones. When you're at 80% maximum heart rate, the heart rate on Band turns orange. At 90%, it turns red.

It's not yet clear whether this is just when working out in the gym or when running or cycling - I suspect it's all of the above. If you're able to trigger this then maybe you can comment? Actually, I'd like to see Microsoft go further, with more 'zones' for the (ahem) older users, perhaps green for at 70% max heart rate.