Kinanthropometry of Group I rugby players in Buenos Aires, Argentina

The large variability in size and structure between playing positions in rugby merits specific kinanthropometric profiling. We aim to report detailed descriptive anthropometric data of a sample of 133 rugby players stratified by field positions (age 24.3 +/- 3.6 years, body mass 89.5 +/- 13.2 kg, and stature 178.8 +/- 7.3 cm) belonging to seven Group I teams competing in the Buenos Aires Rugby Union, and to find out if front row forwards (FR) have larger muscle and skeletal parameters. Body composition was analysed with the five-way fractionation method, expressing tissue masses in absolute terms, relative to weight as percentages and to stature as phantom z-scores. Furthermore, somatotype, body mass index, sum of six skinfolds, and muscle-to-bone ratio were calculated. Players were subsequently grouped into three positional clusters and muscular-skeletal elements compared, showing FR to have larger proportional muscle and skeletal structure than remaining forwards and backs (P < 0.001), albeit a similar muscle-to-bone ratio (P = 0.060). When compared to a sample of the top six teams at the 2003 Rugby World Cup, the Buenos Aires players were considerably smaller, measuring, on average, 3-11 cm less in height and 6-13 kg less in weight.