The warm-up went well (small victory) and then the first 20 minute variable intensity interval got going; easy at first then ramping up. I was hanging in until about 13 mins but I was unable to complete the interval as planned so I dropped into 'recovery mode'. Rather than stopping I back off a little and try to let my body recover, slowly picking up power or maintaining power until the end of the interval. I think this is much better than stopping. Below is a plot of the first interval, Red = HR, Black = power and Blue = speed.
After a 5 minute rest I was ready for the second interval, but I'd backed the intensity off to 95% to give me a chance of completing it; or so I thought. Again, about 13 minutes I got a bad dose of 'the weakness' and I had to back off into recovery mode, getting my HR down and then slowly building my power until the end of the session. I was able to finsh with a flourish and beat the final power peak, but it was a hollow victory after all the recovering I'd done prior to it.
I didn't enjoy it and I don't think I'll be doing it again too soon. If I do it again I'll drop the intensity down to make sure I can get to the end. Considering I can achieve 2x20 at 307W, I'm slightly confused why I only achieved 1x299W then 1x290W on the 20 min intervals today. It is probably the peakiness of the intervals demonstrating the effect that variable pacing has on an interval.