To compare a field-based critical velocity running test to routine laboratory (treadmill VO₂ 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.Single cohort, cross-sectional study involving 22 female Australian Rugby 7's National team players.Players underwent fitness testing comparing the critical velocity test (100 m, 400 m, 1500 m runs) to the Yo-Yo IR1 and a treadmill VO₂ 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.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 VO₂ max test, however mean values were substantially different between tests (Yo-Yo IR1: 4.3 ± 0.1 ms(-1), vVO₂ max: 3.7 ± 0.3 ms(-1), critical velocity: 3.2 ± 0.3 ms(-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).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.