I don’t know if you are a member of the ACSM or have access to their journals, however, here are two peer-reviewed studies you might find of interest.
I am sure if you google the titles, the researchers names will come up with the study.
1. Arterial Saturation During Maximal Exercise Depends upon Capacity to Increase Ventilation.
2. A Comparision of Incremental Exercise Tests During Cyucle and Treadmill Ergometry.
Best to you.
Exercising makes the person breathe in more oxygen. The hemoglobin, a protein in the red blood cell, is bonding with the oxygen in the bloodstream. To give you energy for moving, the oxygen is being delivered to the working muscles.
Is it not amazing how the body works and how much we are still learning?