they become flabby and smaller.
They weaken
When leg muscles are not used for an extended period, they can atrophy and weaken. This can lead to reduced muscle mass, strength, and endurance. It may also result in loss of flexibility and coordination in the muscles.
Astronauts' muscles atrophy in space due to the decreased work they do without Earth's gravity.
Atrophy
cardiovascular fitness
Everybody dies. That's it.
That is lactic acid. This is what produces a "burning" feeling.
Leaving the oven on for an extended period of time can lead to overheating, potential fire hazards, and damage to the oven itself. It can also result in wasted energy and increased utility bills.
They get caught in the storm and end up on the island for an extended period of time.
Focusing your eyes on the paper for an extended period of time can strain your optic muscles and nerves, causing headaches or soreness of the head.
If it is exposed to sunlight while being in excessive heat it can damage the internals of the camera.
The extended period at the wicket by two batsmen in cricket is called a stand.