Most parents want the best for their children, both academically and athletically. And many parents push their children, both in school and on the playing field. It is widely acknowledged that too much pushiness can backfire psychologically; what is less well known is that it can also backfire physically.
Ten years ago a boy on the local swimming team told me that his doctor told him that he was in the middle of his growth spurt, but that he wasn't growing it because he was expending so much energy in the pool. He ended up 5' 7". A child between the ages of 12 and 16, the prime growing years, who is constantly working out to the point of exhaustion, needs all his physical resources to merely recover from his workouts. So growth takes a back seat.
Part of the problem is that everyone knows that in most situations, hard work pays off. And most coaches believe in such athletic cliches as "no pain no gain" and "no guts no glory." To a certain extent, all of these are true. But if a little of something is good, a ton of it is not necessarily better.
This local swimming team is a case in point. I've noticed over the past twelve years that the boys who push themselves the hardest, the ones who rarely miss a practice between the ages of twelve and fifteen, often end up around 5' 6" or even less. There seems to be an effect with girls as well, though with them the effect seems less pronounced for some reason. This observation was recently confirmed by the New York Times, which stated that stress such as malnourishment stunts boys' growth more than girls'. (A child who is overtraining is effectively malnourished since so much of his protein and calories must go towards just recovering from workout.) This condition is exacerbated by the fact that the swimmers who train the hardest are the ones who get promoted to the next training squad, where their reward is to do even more yardage. The local team has a reputation for being a big yardage team. Over this past Christmas vacation, for instance, on one day the coach assigned his senior swimmers a set of thirty 400 yard individual medley's, a twelve thousand yard set, over the course of three hours. That's over six and a half miles in one three hour session. The next day, they swam for a total of four hours. The third day, assigned them sixty 200's, a set of the same distance. The day after that, they swam for four hours again.
What's worse is that the kids often miss valuable sleep time, getting up as early as 4:30AM to reach the 5:30 AM practices on time. If you're up late doing homework, say till 11PM, that means that a theoretically growing child will end up with only five and a half hours of sleep, and sleep is the only time that the body grows. The result? Of the boys on the highest level squad who had been on the team between the ages of twelve and fifteen, only one was as tall as his father.
About six years ago one of the boys' mothers told me that they used to joke that there was something in the water which prevented their boys from growing. In a way, they were right, but it had nothing to do with the pool's chemical content. It had to do with the amount of time the boys spent working out in it. I've met many of them, and they all seem like nice kids. This is part of the problem. When the coach pressures them to show up to more workouts, and swim harder during the workouts, they do what well brought up youngsters do: they defer to the elder in the position of authority, assuming he knows best.
Another effect of too much exercise is that it's hard to grow muscle. Of the boys on the squad who did reach normal height, most were abnormally skinny. When you're constantly tearing your muscle down and don't give your body a chance to recover, you'll end up looking malnourished no matter how much you eat.
The team does occasionally come up with very good swimmers. But when you look closely, these tend to be the kids who joined the team at age 15, already full grown, or kids who go to private boarding school and only swim with the team part time. There was one excellent swimmer who was purely a homegrown product, but the head coach used to complain about him that he skipped 45% of the practices. I'm not sure whether it was laziness or an instinct for self-preservation that caused him to do this, but if he had shown up to all the practices, he probably wouldn't have been nearly as fast.
Every coach wants to have a champion upon whom he can build his reputation. And everybody in swimming has heard stories of the incredibly long, tough sets that great distance swimmers have done. So coaches are wont to assume that if they have their swimmers do similar sets, that they will produce champions. The problem is that different people have different metabolisms. The ones who end up as champions are the one with the most naturally strong constitutions. Their stomachs, kidneys, liver, heart, and lungs just naturally produce more energy than most peoples'. And, just as importantly, they usually have more natural testosterone in their systems than others, so their bodies just tend to put on more muscle. (Some cheat by using steroids, but that's another matter.) Most children are just not naturally cut out to be champions. And when they try too hard, they pay a price, either by having their growth stunted or by ending up abnormally skinny. The situation bears a resemblance to Charles Dickens' England, where young children were made to get up early to work in the factories for eleven hours a day; they did not grow tall either. The difference is that those children were just being exploited, whereas the parents who push their children athletically want the best for them. The end result, however, is similar.
Ironically, overtraining doesn't even help kids swim fast. Being tall is a major advantage in swimming. (Every time a tall person takes a stroke with his long arms, he goes that much further.) You'll never see a short swimmer at the Olympics, except occasionally in the distance freestyles or in the breaststroke, and you'll see many exceptionally tall ones.
The real tragedy of this situation, of course, is not that the boys don't reach their full potential athletically. After all, a sport is just a sport. It's that these boys have to go through the rest of their lives short. There have been countless studies showing how height helps in various ways in our society, whether in terms of the amount of money you're paid or the way other people perceive you or the range of potential mates available.
It's not just the coaches who are responsible for this, though any coach who constantly works his charges to the bone without sufficient recovery time certainly bears a large responsibility. I've noticed parents who shuttle their kids from a practice in one sport to another in a different sport without even feeding them in between. These parents think that they're producing little supermen this way, but they're doing the exact opposite. Many of the cases I've seen where the children do two sports in one season result in the smallest children of all.
Another crucial factor is, of course, diet. Children who train very hard are frequently operating on a nutritional deficit, and must be fed constantly and well. Parents who don't pay attention to this are destined to have smaller children. Even worse is when a chubby 13-year-old decides to go on a strict diet at the same time that he overtrains; he is almost guaranteed to lose several inches of growth.
Most sports by themselves will not stunt growth. It's only the ones which require extremely high energy output, like swimming, or extremely long practice sessions, like gymnastics, which have this effect. A baseball player can do a number of wind sprints, toss the ball for a while, and do drills without having any effect on his growth. In fact, a little exercise is probably good for growth, as it stimulates the body's circulatory system. Swimming done in moderation is actually one of the safest sports, as there are no impact injuries (water is a very forgiving medium).
Some people were never destined to be giants, even with all the sleep and rest in the world. And there is of course no way of proving how much growth was lost due to overtraining in the case of each individual child. For that, you'd need to have two genetically identical versions of the same child, and have one overtrain while the other did more moderate workouts. Such an experiment would be extremely cruel and inhumane. But in fact it's being carried out daily by all sorts of ambitious coaches and parents.