Bigger is not always better.
Smaller players are not necessarily most at risk of injury.
General normative data should not be applied to specific populations.
Participation in sport seems to decline from adolescence into early adulthood 1. Adolescence is a critical period in a child’s development across all areas (physical, emotional, mental, etc.), and some care should be taken when letting one’s child enter sporting situations. Also, the rate of development may vary for children of the same chronological age. This has implications for the physical maturation of the child. For example, two 14 year old boys may have a 50cm difference in height or a 35kg difference in weight. The rate of development varies in timing, duration, and tempo. Based on this, it is high likely that young sportsmen and women would come up against opposition that are developmentally different to them during competition. This raises some questions…
“What are the permutations of mismatches in physical attributes and performance?”
Krause et al. (2015) tested 485 male adolescent (u12-u15) rugby union players in the first half of the 2013 season in Australia. The data collected were demographic information, body mass, stature, counter movement jump, and sprint speed. In comparison to their positional counterparts, forwards were taller and heavier, while backs had better sprint times and relative power. Body mass, speed, and power data were divided into age-specific tertiles (thirds) for better comparison. Only 6% of players were in the highest tertile for all three of these attributes, while only 4% were in the lowest tertile. Therefore, only few players had a distinct advantage or disadvantage over their peers. While this remains a complex issue, being physically bigger does not necessarily translate into performance advantages.
“Should my child be playing in a different age group if he/she is considerably bigger or smaller?”
In short, probably not. As mentioned above, very few players had distinct advantages or disadvantages across body mass, speed, and power. Also, Krause et al. study found that the heavier players reported missing games more frequentlydue to rugby-related injuries compared to their smaller counterparts. The disproves the assumption that lighter/smaller players may be at higher risk of injury.
“How applicable are existing criteria for making these decisions?”
When compared to general age-related normative data for body mass, it was found that u12-u13 rugby players were in the 50th-75th percentiles, while u14-u15 players fell above the 75th percentile. What this means is that we should not be using general population normative data to inform decisions for specific populations, in this case, youth rugby players. Keeping in mind that this data were collected in Australia, and might not apply to other countries, Krause et al. suggest that players below age-specific body mass set-points can be considered for “playing down”. See below.
- Australian Bureau of Statistics. Participation in sport and physical recreation, Australia, 2011–12 – characteristics of persons who participated, 2013.
Available at: http://www.abs.gov.au/ausstats/abs@.nsf/Products/4177.0~2011-12~Main+Features~Characteristics+of+persons+who+participated?OpenDocument [Accessed 23/09/2015].
- Krause, L. M., Naughton, G. A., Denny, G., Patton, D., Hartwig, T., & Gabbett, T. J. (2015). Understanding mismatches in body size, speed and power among adolescent rugby union players. Journal of Science and Medicine in Sport, 18(3), 358–363. doi:10.1016/j.jsams.2014.05.012
University of Cape Town