You can climb cliffs, swim through rapids, lift boulders, and so much more. Your body is a valuable tool that you have honed to perfection.
Experience: You gain athletics experience if you have lost Stamina as a result of physical exertion, or defeated someone in a physical (non-deadly) competition.
Complication: You pull a muscle! Until you regain Stamina, you have disadvantage on rolls using that muscle and can't use Athletics powers that rely on that muscle.