He probably should have taken his hands out of his pockets.
HIIT or Sprints - I said it before and I'll say it again. You're not going to chase a suspect for a mile. Some cops may, but most know that's what the patrol car is for. Most cops are going to sprint after a suspect to catch them and that's where you should be at your strongest while having fuel left in the tank for a little ground scuffle. A good training tip would be to run a 50 yard sprint and at the end of it, try and take down and handcuff a training partner. Repeat this 5 times. It's one of the best ways to prepare you for the real life situation. You need to learn/condition yourself to wrestle and detain a suspect through exhaustion.
This is one of my favorite throw back photos from @muzzleflash83