Related Clues:

• They may be pulled
• Source of strength
• Sinews
• Power source
• Tendons
• Strings you might pull
• Power sources
• Muscles
• Iron-pumpers' displays
• Muscle-bone connectors
• Hamstring components
• Jumper's cables?
• Source of strength, figuratively
• Muscle-to-bone connectors
• Muscle joiners