Help! The smallest kid at school beat me in a race!!!?

OMGOMGOMG... YOU HAVE TO EXPLAIN THIS IMPOSSIBLE SCENE... I am kinda a couch potato that plays halo 3 all day. But a lest I play 2 hours of basketball ever weekend! But I am no fatty because I just am not, and I am extremely big and strong! I'm 13 years old, 5 feet 7 inches and 156 pounds. Even through I'm not that good at running, I still am so so! But... the problem is... a really small kid came to my school last week... He told everyone he was very fast and bragged about it.... He said he would show his true speed to anyone who wanted to race him... Even through I'm not that good at running, that kid is tiny!!! He's 4 feet 5 inches, 67 pounds, and the rest about him I don't know. So after my challenge was accepted we lined up at the start of the race during PE free time. The race was for 1 mile. At first I took off at a moderate speed and kept up with him... Than towards the middle we traded leading positions randomly... This continued until the middle of the 3rd lap................. Than I started to get some burn in my legs and got very tired. I thought he would have gotten tired too since he's so small!!! Than I slowly slowed down as my energy depleted. As I started jogging weakly he continued at the same speed and the same force!!! Omg he continued and by the time he reached the finish line I was too weak to even walk!!! OMGOMGOMG... how could this happen!!!! He's this small, he appears cute, his legs are smaller than my Xbox 360, and like everything is defining the laws of movement!!! Omg I'm not that bad at running!!! OMG... All the fast kids tried to race him and they all lost even through they run everyday! He told us the only sport he plays was soccer!!! Explain now!!!!!