Related Clues:

• Earth's center
• They may be ripped or crunched
• Belly muscles
• 'Six-pack' muscles
• Car safety feature, for short
• 'Washboard' muscles
• Units in a six-pack?
• Workout target, for short
• Central theme
• Muscles
• Sit-up beneficiaries
• They may be ripped on the beach
• Tummy muscles, for short
• Sit-ups sculpt them
• Pear discard