Female athletes are required for a study investigating the effect of exercise intensity on the immune response to exercise. The researcher is looking for healthy woman who are not taking oral contraceptives aged between 18 and 40. They will be asked to attend 4 sessions, the first being a lactate profile and V02 max, the 2nd, 3rd and 4th being a 30min run at different intensities. On completion of the study, they will be offered the chance to do another V02 max test, on the bike if they prefer. The study is being undertaken at Brunel University, Uxbridge, West London. For further information, please contact Elizabeth Gough (Elizabeth.Gough@brunel.ac.uk).