You are returning a serve, your partner is at the service line, and the ball you are returning is hit into the forehand or backhand corner, forcing you wide. What should you do next? Why?

If it's a smaller child or infant, place one on the middle of the chest and on the child's back. (if it is a bigger child with enough room for two, place one on the upper right/your left of the chest, and one on the lower left/your right) the pads should never touch each other. 

Subtract your 2-minute heart rate from the heart rate you took immediately after exercising. the faster your heart rate recovers (or slows down ) the fitter and healthier your heart. if the difference between the two numbers is: less than 22: your biological age is slightly older than your calendar age