If someone has a resistance training pattern of multiple times a week. One day there is extensive cardiovascular training, with the intention to use fat as energy. Will protein ingestion during the cardio, which can be > 4 hours, be used as an energy sources for the cardiovascular activity, or will it be used as amino acids to recover the muscle micro damage from the resistance training? I am looking for articles and/or views.
My idea is that the protein will be used for muscle recovery, as long as the intention of the cardiovascular activity is not to high. When glycogen is lower after a few hours, and fatty acids get burned, a higher intensity could use the amino acids in that case. So moderate pace will be the clue.
Thanks in advance