A good amount of the power increase you see during training is from increased efficiency at producing force through the pedals.
There’s a number of ways to increase this efficiency:
-
More efficient FFA [Free Fatty Acid] metabolism transport and metabolism - more power.
-
More efficient oxygen uptake - more oxygen to the mitochondria equals more power.
-
More efficient neurological muscle recruitment - more/faster muscle activation equals more power.
-
Faster muscle recruitment / increased rate of force development allows for quicker responses to load changes. If you look at your interval power vs. target power you may notice it is closer to the target faster in the interval. When you ‘normalize’ this it becomes apparent that the reduction in lag leads to a higher power average.
Your power growth will be slowed if you can’t provide fuel substrates to your muscles. Dipping into your fat cells to cover the overage will work for a while, but there’s efficiencies in training to be had if you properly fuel … since faster fuel uptake will allow you to further take advantage of the benefits of training.
It’s all cumulative as well, right? If you get 1% more adaptation per session by adding more fuel, well, where does that leave you after 25 sessions?