Last week I cycled to the doc's (about 2.5 miles), and had a blood test (full blood count and colesterol), then cycled home. My arm felt sore - bruised after but there was nothing to see so I thought I was a complete wimp. After 2 days my arm turned black, blue and brown along the inside and underneath for about 6 or 7 inches long. And its still giving me greif even now. Did I just have a bad blood test? or is it bad to cycle after a blood test.? cos you keep your arm straight when cycling, and I guess you are pumping the blood around a little more. If I had applied an elastic bandage would that of helped?