Other than FTP, What are some subtle ways to see if you're gaining fitness?

[DaveWh]

I’d like to become more like the dashed line in this chart.

Not as easy to measure as FTP unfortunately.

Thanks to @Mikael_Eriksson for this:

FTP Energy Source?

@madman2 and @DaveWh already gave some great answers. To add my two cents: The one thing I would disagree with from @madman2’s response is that it’s hard to change only one system at a time (aerobic or glycolytic). It can be done, but requires careful consideration of how to train and knowledge of your own physiology and metabolism. Although nutritional strategies can be used to alter the contribution of aerobic oxidative/glycolytic energy at any given power, the very large part of change…