Why can steady exercise feel easier after an initially difficult start?
Show answer & explanation
Answer: Oxygen use and circulation adjust to the ongoing effort
Muscles suddenly unlock a separate hidden fuel supply — Muscles do not unlock a separate hidden fuel supply. They already use a mixture of available fuels, and the balance changes gradually with intensity and duration.
Oxygen use and circulation adjust to the ongoing effort ✓ — Oxygen use and circulation increase after exercise begins, helping support a steady effort. This adjustment can contribute to feeling more comfortable, but there is no universal ten- or twenty-minute switch and the feeling can have several causes.
The lungs suddenly double in size to hold extra air — The lungs do not suddenly double in size during a workout. Breathing becomes faster or deeper as needed while circulation and oxygen use adjust.