Aerobic exercise physiology in a professional rugby union team.

Introduction: In professional rugby, different positional roles may require different levels of aerobic fitness. Forward and backline players from a team of elite rugby players were tested to evaluate the differences between the two groups.

Methods: 28 male players, 15 backs and 13 forwards, underwent maximal treadmill cardiopulmonary exercise testing (CPX), lung spirometry, a 3 km timed run, and body fat measurement.

Results: Peak oxygen uptake was higher in backs than in forwards (peak VO(2) 48.3+/-2.1 vs. 41.2+/-2.7 ml kg(-1) min(-1), P<0.05) with no significant difference in peak respiratory exchange ratio (1.08+/-0.02 vs. 1.07+/-0.02, P=NS), exercise time (1306+/-39.7 vs. 1217+/-25.1 s, P=NS) or time for 3 km run (667.5+/-14.1 vs. 699.0+/-20.7 s, P=NS). However, the forwards were taller and heavier (height 190.2+/-2.2 vs. 179.5+/-1.3 cm, P<0.001, body mass 104+/-2.4 vs. 86.3+/-1.7 kg, P<0.0001) and had a higher fat content (body fat percentage 12.8+/-0.8 vs. 9.7+/-0.6%, P<0.01) and forced expiratory volume in 1 s (FEV1, 4.9+/-0.1 vs. 4.5+/-0.2 l, P<0.05). There was a significant negative correlation between peak VO(2), 3 km run time (r=-0.45, P<0.05) and weight (r=-0.54, P<0.003) for all subjects.

Conclusion: Backline players have a higher peak oxygen uptake per kilogram than forwards, although the cardiopulmonary exercise test duration, degree of anaerobic metabolism and 3 km run time are not significantly different. These results could be due to the two groups' different body structure, being shorter, lighter and having a lower percentage body fat. These differences, which are likely to be a result of selection for specific roles in the game, should be taken into account when evaluating aerobic fitness within a rugby team.