The aim of this study was to investigate maximum aerobic power (VO₂ max) and anaerobic threshold (AT) as determinants of training status among professional soccer players. Twelve professional 1st team British male soccer players (age: 26.2 ± 3.3 years, height: 1.77 ± 0.05 m, body mass: 79.3 ± 9.4 kg) agreed to participate in the study and provided informed consent. All subjects completed a combined test of anaerobic threshold (AT) and maximum aerobic power on two occasions: Test 1) following 5 weeks of low level activity at the end of the off-season and Test 2) immediately following conclusion of the competitive season. AT was assessed as both lactate threshold (LT) and ventilatory threshold (V_T). There was no change in VO₂ max between Test 1 and Test 2 (63.3 ± 5.8 ml·kg^-1·min^-1 vs. 62.1 ± 4.9 ml·kg^-1·min^-1 respectively), however, the duration of exercise tolerance (ET) at VO₂ max was significantly extended from Test 1 to Test 2 (204 ± 54 vs. 228 ± 68 s respectively) (P<0.01). LT oxygen consumption was significantly improved in Test 2 versus Test 1 (P<0.01) V_T was also improved (P<0.05). There was no significant difference in VO₂ (ml·kg^-1·min^-1) corresponding to LT and V_T. The results of this study show that VO₂ max is a less sensitive indicator to changes in training status in professional soccer players than either LT or V_T.