"If you can jump," says rebound expert Al Carter, "you can rebound."

But before you leap on a rebounder, he says, look over these three major precautions:

1. Consider how rebounding might affect any pre-existing health problem--headaches, stomach aches, weak knees. If you're unsure, consult your doctor.

2. People with phlebitis probably shouldn't rebound since they could break loose a blood clot.

3. Anyone with detached retina problems should not rebound.

For beginning 'bounders, Carter offers these jumping ideas:

* Health Bounce. Using toes and calf muscles, move gently up and down in the center of the rebounder with your feet remaining on the mat.

* Aerobic Jog. At your own speed, walk, jog or run. Lift knees high for strength and flexibility, move fast for a greater aerobic workout. If you need help with balance at first, hold onto a door frame or touch a wall.

* Strength Exercise. Use toes, knees and calf muscles to bounce as high as you can off the mat; then land in the center and regain balance.

* Twist. Bounce so that hips and legs turn left and chest and shoulders turn right. On the next bounce reverse the motion. Continue alternating sides.

* Dance. Put on your favorite music and "get down."

* High step kick. Advanced rebounders can try kicking out one foot, bouncing on both, then kicking out the other foot.

* Sit-jump. While sitting in the middle of the rebounder, start bouncing by moving your shoulders and arms.