One of the most dramatic developments in youth sports over the last ten or fifteen years has been the explosive growth, at seemingly ever-earlier ages, of the number of highly selective, highly competitive sports teams (the so-called elite, travel, select, premier and Olympic Development teams), and the related trend toward early specialization (playing a single sport on a year-round basis to the exclusion to all others).
Supported by myths not facts
The trend towards early specialization (to be distinguished from starting early, which, for some sports, such as ice hockey, is important), and an increasingly professionalized approach to youth sports, appears to be driven more by folklore, myths and half-truths, a herd mentality, the ever-burgeoning youth sports industry, and by adults more intent on winning than acting in the best long-term interests of children, than actual, cold, hard evidence.
There appear to be three main reasons.
1. Parents are looking for an edge. In our increasingly winner-take-all society, parents, coaches and kids appear to be searching desperately for an edge in the often fierce and political battle for scarce spots on high school varsities, and, with the cost of college increasingly out of reach for many families and good paying jobs after college hard to come by, for the college athletic scholarships and possible professional careers, an edge which they think select teams and specialization will provide - or, at the very least, a way to keep up with their peers.
2. Parents believe that more is better. More and more parents are buying into the idea - one that many youth sports organizations, the college sports industry, coaches, and even best-selling authors (e.g. Malcom Gladwell's "10,000 hour rule" of "deliberate practice ) actively promote - that their child will be unable to attain success or even make a high school or college team without specializing, playing on a select team, playing year round, and attending special sports camps in the summer. Many parents have come to believe that more (more teams, more practices, more intense and competitive games) and earlier (travel teams at age seven!) is somehow better.
3. Parents think it is a matter of competitive survival. More and more parents are signing their children up to play in a select travel program or allowing them to specialize in a single sport before high school because they feel they have no other choice, that it is a matter of competitive survival. Parents assume that sports are like academics; that because a child who falls behind academically, even in the early grades, may never catch up - a fear that prompts more and more parents to push their children in school, even in the early grades, and hover over them (spawning the phrase "helicopter parents") - the same must hold true in sports. In doing so, many parents appear to be ignoring their own better judgment, intuition (which suggests that early specialization and playing on select travel teams may actually be unhealthy), and the evidence (a 2012 study, for instance, found that boys age 10 to 12 who play multiple sports, especially many hours per week, instead of specializing early, are more physically fit and have better gross motor coordination than those who specialize).
Just as parents who drill their second-grader on questions from the Scholastic Aptitude Test have lost sight of the fact that the best way to prepare a child for college isn't to teach by rote but to raise a child who loves to learn, the best way to prepare a child to be a successful high school athlete, in my view, is to instill a love of sports, not to apply so much pressure on him at an early age by exposing him to the stress of ultracompetitive elite sports programs that he comes to see sports not as fun but as a job, burns out, or suffers overuse injuries that, in some cases, result in permanent physical impairment (such as early arthritic changes in a knee after reconstructive surgery for a torn ACL, the risk of which, at least one study suggests, is linked to early specialization).
Nine reasons against early specialization
The majority of studies suggest that early specialization can have "significant negative consequences on the development of an athlete over time."
Far from being supported by hard scientific evidence about youth talent development, the trend towards early specialization and playing on travel or select teams at an early age (before grade six) is a bad idea because it:
1. interferes with healthy child development; [1,3,4,5]
2. comes with psychological risk from stress associated with over-involvement and expectations of parents and significant others;
3. doesn't guarantee future athletic success;[2,4,5]
4. hurts, rather than helps, skill development; [2,3,4,5]
5. is elitist; 
6. leads to overuse injuries; [2,3,4,5]
7. promotes adult values and interests, not those of children;[2,4]
9. reduces the chance that children will stay active in sports as adults.
Just say no
If parents choose not to allow their child to specialize or play on a select team too early, not only will they be doing that child a huge favor, but, if enough parents "just say no" to select teams and early specialization, we can create the balanced, child-centered youth sports system our children deserve and reduce the alarming number of overuse injuries kids are suffering, fully half of which, believes the National Athletic Trainers' Association, could be prevented if kids took one season off out of four from sports, and delayed playing a single sport all year round until high school.
Easier said, than done, I'm afraid, but food for thought.
1. Franzen J, Pion J, et. al. Differences in physical fitness and gross motor coordination in boys aged 6-12 years specializing in one versus sampling more than one sport. Journal of Sports Sciences, DOI:10.1080/02640414.2011.642808 (available online ahead of print: 03 Jan 2012).
2. Jayanthi N, Pinkham C, Dugas L, Patrick B, LaBella C. Sports Specialization in Young Athletes: Evidence-Based Recommendations. Sports Health: A Multidisciplinary Approach 2012;20(10). DOI: 10.1177/1941738112464626 (published October 25, 2012 ahead of print).
3. Mostafavifar AM, Best TM, Myer GD. Early sport specialisation, does it lead to long term problems? Br J Sports Med. 2013;47:1060-1061.
4. Sagas M. What does the science say about athletic development in children. Research Brief, University of Florida Sport Policy & Research Collaborative for the Aspen Institute Sports & Society Program's Project Play. September 13, 2013 (accessed at http://www.aspeninstitute.org/sites/default/files/content/docs/events/At...).
5. DiFiori JP, Benjamin HJ, Brenner J, Gregory A, Jayanthi N, Landry GL, Luke A. Overuse Injuries and Burnout in Youth Sports: A Position Statement from the American Medical Society for Sports Medicine. Clin J Sport Med 2014;24(1):3-20.
6. Gladwell M. Outliers: The Story of Success. (New York: Little, Brown & Co. 2008)
7. Russell WD, Limie AN. The relationship between youth sport specialization and involvement in sport and physical activity in young adulthood. J Sport Behav. 2013;36(1):82-88.