Objectives: To compare a field-based critical velocity running test to routine laboratory (treadmill VO 2 max test) and field-based (Yo-Yo intermittent recovery test, Yo-Yo IR1) aerobic fitness tests in women's rugby sevens (7's) players. To quantify the degree of association between field-based fitness test scores and GPS-derived analysis of performance data in competition. Design: Single cohort, cross-sectional study involving 22 female Australian Rugby 7's National team players. Methods: Players underwent fitness testing comparing the critical velocity test (100m, 400m, 1500m runs) to the Yo-Yo IR1 and a treadmill VO 2 max test. GPS data was obtained during the National Championships using a subgroup of 12 players and compared with each player's fitness test scores. Results: The critical velocity test was highly correlated with the Yo-Yo IR1 test (r=0.86, 0.69-0.94; 90% confidence interval) and all variables of the VO 2 max test, however mean values were substantially different between tests (Yo-Yo IR1: 4.3±0.1ms -1, vVO 2 max: 3.7±0.3ms -1, critical velocity: 3.2±0.3ms -1). Average speed, obtained from GPS data, was largely correlated with both the Yo-Yo IR1 (r=0.62, 0.10-0.87) and critical velocity (r=0.51, -0.06-0.83) tests. Total game distance correlated moderately with the Yo-Yo IR1 (r=0.49, -0.09-0.82) and critical velocity (r=0.36, -0.25-0.76). Conclusions: The critical velocity test is an appropriate aerobic fitness test, yields results similar to the Yo-Yo IR1, and correlates moderately with rugby 7's game data. However the Yo-Yo IR1 and critical velocity test scores cannot be used interchangeably.