The heart rate analysis features of GPSLog Labs have had some big updates:

Firstly, you can now set up heart rate training zones for each tag.

Each zone can have a name and an upper heart rate, to assist configuring the zones, you can set your resting and maximum heart rates and the percentage of your heart rate reserve (maximum - rest) for each zone is displayed.

Once these are set up, you can see breakdowns of the time in each zone on the activity detail heart rate tab:

And best of all, on the activity tables for a log or route, the proportions of time in each heart rate zone are shown as colours in the background of the table cell:

To assist in calculating your heart rate zones, I've also created a maximum heart rate calculator page. This page is accessible without a GPSLog Labs account and might help you wade through the mass of different formulas for calculating a maximum heart rate that are out there (or at least the ones on the Wikipedia page.)

It's been possible for a while now to upload additional heart rate data for an activity. This allows you to use a stand-alone heart rate logger (such as a Polar HRM) if your GPS logger doesn't record heart rate directly.

The upload process has been made more flexible, it now imports data from more formats (such as GPX and Garmin Training Centre TCX) and will automatically detect the format.

The uploaded heart rate files are now stored together with the log files and will be automatically reapplied after processing or editing filters.

There's a new tab on the uploaded log file page where the heart rate data can be previewed and downloaded or removed too if necessary.

Heart rate data can also be uploaded for manual entries, for example for data logged on a treadmill or wind-trainer.