# Workouts Why 'Power Low=' and 'Power High=' Values?

I have used a text edit to modify some workouts (to duplicate interval pyramids etc.) but in all my workouts the ‘Power Low=’ and ‘Power High=’ Values are set the same be they SteadyState durations or Intervals so my question is why ‘Power Low=’ and ‘Power High=’ Values?

Example,

<IntervalsT Repeat=“4” OnDuration=“60” OffDuration=“540” PowerOnLow=“0.79449993” PowerOnHigh=“0.79449993” PowerOffLow=“0.65449995” PowerOffHigh=“0.65449995” OverUnder=“1”/>

Also what is the difference between and under/over interval and one where that parameter is not set. Some seem to list the parameter some don’t. How do this parameter affect the work out and you target wattage?

PS The ‘Over/Under’ parameter only appears (as far as I can see) on intervals where to are alternating between Z2 & Z3 or Z3 & Z4. Its not there on my workouts when going between Z3 or Z4 and a active recovery period i.e Z1. Hope this make sense.

Can we have a document explaining how to edit the XML file and what the tags mean and do?

I can understand most of them but some I’m trying to work out by trial and error. I find the in program editor a bit time consuming when repeating blocks of training.

Your first paragraph in your first post doesn’t make sense.  Are you questioning my the PowerLow and PowerHigh values are always the same?

If you are then you are creating an interval which starts at a certain intensity and continues at that intensity until the interval finishes.

If you put in a higher value for PowerHigh then the power required to successfully complete the interval will raise during the interval, ie you will not ride a consistent amount of watts for the full duration of the interval.

Ah, so there are kind of ramp intervals. Didn’t know you could increase the required wattage during a interval. I assume the same applies then to the ‘Rest’ or ‘off’ peroid. I will try it. Can’t see how you do that in the app. Ill look again in the morning. Thanks.

Exactly, a ramp interval.

When creating an interval, when you rang and drop the interval type from the right hand side of the screen, select “warm up” or “cool down”.  Although it is called a “warm up” it doesn’t have to be the first interval in the work out.

In theory I think these could be quite interesting. I raised a feature request though stating that I didn’t like how Zwift rounded your intensity to the nearest 5 watts regardless of the interval intensity percentage.  This rounds makes ramps a little crap to me.

You also can’t state the rate at which it ramps up.

my guess is that “PowerLow” and “PowerHigh” designates the range of acceptable power before that client will announce “more” or “less” power. If you fall outside of that range for more than 7 seconds (?) then ERG mode gets disabled.