I've got a high school girl in my group that's driving me nuts. She can run 63 seconds for 400 metres but when i ask her to run an 800m at 69 seconds+68 seconds on the second lap she just explodes whatever time she runs on the first lap. It just doesn't seem to matter whether she runs 63 or 73 on the first lap,the second will always be at 74 or 75, i know she can run real fast but i just can't breakdown the barrier.