Blimey, I was expecting an email notification of replys but didn't get one and on checking back I see many replies! Gordon How much training were you doing? Have you looked in to Overtraining sydrome / unexplained under performance syndrome? I thought this is what I had originally, but in the end it didn't fit, I did however learn quite a lot. One of the ways of identifying mild overtraining is to look at your waking heart rate every day and if it is say suddenly 10 bpm higher when you wake up one day then it is highly likely you have not recovered from your previous exercise session and should treat that day as a rest day. Not sure how much use that is to you but it may be worth checking out? Corina I understand what you mean about SSRI's but the problem with GP's is once you get put on an SSRI or similar any new symptoms are put down as side effects and any if they don't relieve the symptoms you are then pushed up to the maximum dose before having to move on to the next one. Having seen someone go through this in reality coupled to side effects and widthdrawl effect I would rather give them a miss. Katie I wouldn't say I have truely POTS style syptoms, it seems to go on sasy a 4 week cycle. Sometimes my HR only bumps up by 20 bpm from say 45 to 65 bpm then at another point in the cycle it will go from 45 to 120bpm. I never have low BP, its always up in that 140/80 region or higher so I don't get a postural drop. I did ask my GP if my hands look like Raynauds and he said it wasn't Raynauds but he couldn't say what it was. I see you have been diagnosed with Lyme, I had a Negative ELISA and a sub threshold IgG OspC band on the Western Blot which I may consider pushing to be investigated further. What was your experience? Sarah That's an interesting story you have there! I have had two blood and urine tests for catecholamines and metanephrines. The first when I just didn't feel right and everything was in normal limits other than plasma 3-methoxytyramine which had a level of around 250 with an upper reference range of 120. The second when I had the shakes and cold hands I don't have the plasma results for yet but the urine was in normal limits. What were you levels like? I have had no endocrinology refferal or anything else for scans of chest / abdomen etc. The worst I have got in terms on tachy is about 150, ah gone are the days of sitting at that heart rate for a few hours enjoying it as part of exercise! Angie Blimey, that is so similar to my symptoms! How are you managing your diet? I keep asking for advice on this but I don't get much of an answer from the pro's! I don't suppose you have ever had the migraine, horner's or RAPD too have you? Can you give me any more info about what happened when you started on the beta blocker? I am guessing you aren't in the UK? All Thanks for your replies, it's great to have some others who seem to have a clue what I am on about! More than happy to get PM's if you don't want to continue here! Cheers Matt