Strava

Spending a long time in Threshold is one way of training effectively, although I'd question those heart-rate-bands as definitions for the zones; Are those zones configurable or do they adapt or are they fixed and unscientific?

My Garmin takes my inputted resting and max heartrate and does the rest.

It wont explain why my threshold training on the turbo seemed pretty useless when back on the bike. Science can GTFO >>>>>