For a tween or teen athlete, rest is a critical part of her training. I know that sounds slightly counterintuitive given that mastery of a sport requires hours, months, and years of practice. But rest contributes to athletic performance in many ways. The first is simply to avoid injuries. As tween and teen girls train and practice in any sport, they incur microscopic injuries -- tiny muscle tears, a slight strain or sprain. A day or two of rest allows those small injuries to heal and not develop into bigger injuries. Rest is even more critical for year-round athletes whether soccer, softball, swimming, or gymnastics. Those athletes are using the same muscle groups repetitively, so rest is needed to avoid overuse injuries. For example, year-round swimmers often take time off in August (ironic that swimmers aren't swimming during the hottest month of the year). They can bike, run, or laze around but no hard core training. Rest is also important for an athlete's mental game. In sport as in love, "absence makes the heart grow fonder." When your daughter started playing her sport, she likely did so because it was fun. It's still important, at any age and any skill level, for the sport to remain fun. That doesn't mean that the athletes shouldn't work hard, but as coaches and parents, one of our jobs is to nurture the love of the sport. Taking a physical break from training and competition can strengthen that love. Finally, sleep -- the deepest form of rest -- keeps athletes at the top of their game. Literally. These kids work hard balancing school, chores, family commitments, a social life, and sports. As fellow blogger Emma said so well, their plates are really, really full. In order to function at their best, athletes need plenty of sleep to restore body and mind. Most pediatricians recommend an average eight to nine hours of sleep. That means turning off computers, phones, televisions and getting into bed at a reasonable hour. So rest is really a three-legged stool--rest the body to prevent injury, rest the mind to maintain love for the sport, and get a good night's sleep to put it all together.