Hi Danny,
We created a very quick introductory video on how you can use the XATA advice and the real-time focus available on your Garmin (or via Android) to freestyle a workout. Generally, your goal is to accumulate as much time near the target power as possible (increasing the specificity of the ride), but obviously you don’t want to fatigue yourself too much. When I’m aiming to do this, I’ll usually aim for ~50% of the TTE of the recommended power… i.e. if the recommended interval is at my 10 min power, I’ll try to ride it ~5 min. We don’t have ‘zones’, but if you can stay around +/- 10W of the recommended interval, that’s generally sufficient. How many intervals you may do likely depends on many factors that you may need to account for, including what is your recommended XSS target, how fresh are you, are you aiming to get a BT from the workout as well, etc. You can quickly create workout (even if you don’t save it) to give you an idea of how many intervals you need, and how long they need to be (approx).
You’ll notice that it will become increasingly difficult to move the focus duration the longer into the ride that you get, since focus is determined from total strain. This is why the Focus will jump around so much at the start of a ride before eventually settling in to a point where you can start to manipulate the focus towards the target focus via your interval intensity and durations. Generally, anything over a focus of 20:00 is almost pure endurance day, so those days I simply aim to keep the intensity below LTP until I’ve accumulated the recommended XSS.
Hope this is a good starting point. Would like to hear if any other people are using this as well, or if you have any other questions. Cheers