I have a younger brother who is a 14-year-old HS freshman and wants to start running middle distance this outdoor season. He has no previous running background and is mostly sedentary, and he's a couple inches short for his age and very skinny. For the last couple weeks he has been on a few 1.5 or 2 mile runs at about 7:45 pace maybe three times a week. Today he did a time trial on a route that, according to (sketchy) gmap-pedometer.com, was about 0.93 miles, and he ran it in the low 4:50 range. It works out to be around 5:20 pace. What should his training look like coming into track season? He's obviously at a high risk for injury since he'll be going from almost no training to at least five days a week plus workouts and races.