My husband's was down to 35 when he was marathon training and he was really well. doctors sometimes freaked out until we told them it was normal for him
he's now 55 and still fairly fit and it is around 50

Peripheral and axial AS diagnosed October 2011 aged 50, more than 15 years after the symptoms started. Also PCOS, GERD/oesophagitis/dysphagia, IBS, asthma,chronic rhinitis. Taking enbrel, methotrexate, folic acid, omeprazole, vitamin D, metformin, steroid inhaler and eating low starch/low GI.