Hug Knees To Chest
Main muscle: Lower back
Other muscles: Glutes
Fitness level: beginner
Category: Stretching

  1. Lie down on your back and pull both knees up to your chest.
  2. Hold your arms under the knees, not over (that would put to much pressure on your knee joints).
  3. Slowly pull the knees toward your shoulders. This also stretches your buttocks muscles.

Source: bodybuilding.com