I am training for my first triathlon and thought it would be a good idea to have a work out where I ride fairly hard and then run fairly hard immediately after. Well I rode 15 miles and ended at the high school track where I jumped off the bike and put on my running shoes which, I carried in a small bag on my back. I began running and what do you know, I make it 100 yards in about 60 seconds and can't continue no more because of the weird and different pain that I was now feeling. I cooled off and stretched for about 20 minutes then continued to run my two miles I had in mind.
What the heck do I do??? I need to be able to do this if I want to race. Please give me tips, should I be doing something the last couple hundred yards on the bike to prepare, should I not be going so hard for my first time???