| HI!
I am 13 and 5'0 also!
My vertical is about 21"
Here are some good exercises to help you.(Don't overdo or you could mess up your knees)
Instructions
• STEP 1: Begin every workout by warming up your muscles and then doing extensive leg stretches. Because you'll be building muscle fibers that are used for explosive activities such as jumping, stretching is of the utmost importance.
• STEP 2: Jump rope for its excellent cardiovascular conditioning. This step should never be skipped, as it will be an important contributor to your results.
• STEP 3: Sprint. This builds muscle, which will add to your jumping ability.
• STEP 4: Run stairs on your toes. Start by running up a flight, one step at a time. Walk down and run back up, taking two steps at a time. Repeat as many times as you can manage.
• STEP 5: Do sets of elevated jumps (see the next section).
• STEP 6: Do sets of explosive jumps (see the third section).
• STEP 7: Do sets of double jumps (see the third section).
• STEP 8: Rest your legs at least two days a week. Results will come from sustaining the exercise program, not performing it aggressively for a few weeks and then slacking off.
Elevated Jumps
Instructions
• STEP 1: Begin by placing a step bench or platform on the ground (many health clubs have a platform for just this purpose).
• STEP 2: Stand on the platform, then jump backward onto the ground, concentrating on landing softly.
• STEP 3: Jump back onto the platform immediately, with a bouncing motion.
• STEP 4: Complete three sets of 10 repetitions. Be very careful when performing this exercise, as there is a potential for injury.
Explosive Leg Jumps and Double Jumps
Instructions
• STEP 1: Position yourself for an explosive leg jump by facing a secure platform and placing your right foot on it.
• STEP 2: Jump as high as you can, concentrating on exploding off the right leg. Scissor your legs once in the air, then land with your left foot on the platform and your right foot on the floor. Gather yourself and explode upward again, this time off the left foot.
• STEP 3: Do three sets of 10 repetitions, resting for about 30 seconds to 1 minute between sets.
• STEP 4: Execute a double jump by jumping as high as possible with both feet from a stationary position.
• STEP 5: Jump again immediately upon landing, using less effort.
• STEP 6: Repeat until you've accomplished three sets of 10 jumps each.
Overall Tips & Warnings
• Some of these exercises, particularly stair runs and explosive leg jumps, can cause injury if not performed properly. Your knees, in particular, are especially susceptible.
• Make sure you thoroughly understand all instructions before attempting the exercises. | 
Linear Mode
