The present study aims to characterize maximal continuous and intermittent efforts in head-out of water aquatic exercise and to determine the risk associated with this type of exercises by healthy persons. Ten healthy women (38.3 ± 9.4 years; 160.2 ± 6.2 cm; 50.0 ± 8.5 kg) experienced in head-out aquatic exercise participated in this study. Two maximal exercises of (I) 7 min continuous and (II) 3x30 sec leg kick, with 30 sec interval were performed with a two days rest interval. The Rate of Perceived Exertion (I: 19.8 ± 0.4 and II: 19.4 ± 1.0) and the heart rate values (I: 184.9 ± 1.4 and II: 178.2 ± 10.4 bpm) confirmed that both exercises were maximal. The blood lactate concentration was high after exercise in both protocols (I: 12.0 ± 3.4 mmol.kg¯¹; II: 10.7 ± 2.7 mmol.kg¯¹). The systolic blood pressure was higher after both exercises (I: 119.9 ± 19.2 and II: 138.7 ± 15.5 mmHg) whereas diastolic blood pressure was lower (I: 52.6 ± 13.4 and II: 47.8 ± 9.7 mmHg). The mean blood pressure at rest (I: 88.8 ± 12.2 and II: 79.3 ± 8.1 mmHg) and after exercise (I: 83.4 ± 14.4 and II: 78.1 ± 9.8 mmHg) was similar. The higher diastolic blood pressure and double product (I: 26188.2 ± 3955.1 and II: 21899.1 ± 2696.4 mmHg.bpm) for maximal continuous exercise revealed high cardiac effort. Maximal intensity exercises could be safely used in head-out aquatic exercise classes with healthy participants.