Support for heart rate logging in GPSLog Labs has been added for Garmin devices that use the Garmin Training Center format (i.e. .TCX files).

You can see graphs of your Heart Rate vs Time and a histogram of your heart rate on the activity detail page:

Heart rates will be repeated to fill in gaps if the readings occur less than once per second, up to a maximum of 5 minutes.

If you have a device that logs heart rates, and the graphs aren't showing up in GPSLog Labs, please let me know and I'll add support for it.

Note that this will only work for logs out doors where a latitude and longitude is recorded with the heart rate, so if you're using something like a Garmin EDGE705 in indoor mode, you won't be able to view your activity or heart rates.

If you don't have a GPS logger that records your heart rate at each point, you can still record average and maximum heart rates against your activity manually (i.e. based on a non-logging heart rate monitor strap.)

To switch heart rates on manually:

1. Go to tags, and select a tag you want to record heart rates for (e.g. Running or Bike)
2. Edit the tag, click the "Edit heart rates" checkbox.
3. Now, when you go to activity tagged with that tag, you'll see the "heart rate" tab (this usually only shows up if your logger supports heart rates.)
4. On that tab, the average and maximum heart rate values will show "edit", click that, type in the heart rate and click the save button.
   

Once the system has heart rates recorded against your activity (either automatically or entered manually) they will show up in summary and comparison tables and graphs for routes and tags.