What is the meaning of warm up?

verb

• Run until the normal working temperature is reached.
  • usage: "We warmed up the car for a few minutes"
• Become more friendly or open.
  • usage: "She warmed up after we had lunch together"
• Get warm or warmer.
  • usage: "The soup warmed slowly on the stove"
  • synonyms: warm
• Cause to do preliminary exercises so as to stretch the muscles.
  • usage: "The coach warmed up the players before the game"
• Make one's body limber or suppler by stretching, as if to prepare for strenuous physical activity.
  • synonyms: limber up, loosen up