This exercise helps strengthen the quadricep muscles at the hip and the hamstring muslces at the knee. Perform as follows:

• Sit with your legs straight out in front of you.
  
  
• Begin by sliding your heel toward your buttox by bending your knee. Keep your heel on the ground during this motion.
  
  
• Slowly straighten your knee and slide your leg back to the starting position.
  
  
• Relax and repeat 10 more times.