I am a 27 year old female, 5 10 in height and 148 lbs. I have been taking 50mg of vyvanse every morning for about 6 months. (I ve been taking vyvanse for a few years, but have only taken this particular dose for six months). I have always had occasional heart palpitations, and they have worsened slightly since taking vyvanse. I do not consume caffeine of any type. I started running a month ago, and have wondered what effect vyvanse my be having on my exersize, or vice versa. While running I have very little endurance, extreme sweating, and a very fast heartbeat. After 4 weeks I can only run a mike and a half before I cannot breathe anymore, and I was not out of shape to begin with. Any advice?