Possible Clues:

• Get ready for exercise
• Bend and stretch
• Stretch before exercising
• Exercise gently before strenuous activity
• Train mountaineer to avoid cold at great height?
• Do some stretching
• Loosen muscles in preparation for physical effort
• Member, honourable, getting backing — prepare for activity
• Exercise gently prior to much greater exertion
• With plumber I struggle to loosen muscles