This little data field keeps track of how much time you spend in each Zone. The ZONEs are based on % of FTP (a UserSetting you set). I use the Trainer Road and Training Peaks zones (I combined the TR "Tempo" and "Sweet Spot" Zones to make it a little easier to see). For POLARIZED training, avoid the Tempo/SS Zone, and spend closer to 80% in Enduro and 20% mixed between Threshold and VO2. The LAP button resets the Zone % Times so you can start tracking after, say, a warmup. Or track by Lap. You can also set the Short (3-20sec) -vs- Long (30-60s) duration Power Indicators. The default is 10sec and 30sec. You can also turn off the Reset on Lap feature.</p>
v2.6: Added feature to write to the FIT file the Zone Percentages for the ENTIRE activity (not the last lap)</p><p>v2.5: Fixed a minor issue in the display... a floating-point to interger.</p><p>v2.4: Added Lap# and HR to the bottom row</p><p>v2.3: Rounded the Zone Percents rather than set to Integer. Now they will add up to 100% rather than 96-98%.</p><p>v2.2: Added an optional HR Zone indicator that shows you how your HR is running, relative to your power. I've used a formula to map HR to Power Zones, using Coggin's HR and Power zone chart. HR Zone requires that you update the Lactate Threshold HR (LTHR) in User Settings.