If he struggles with the altitude, I'm almost positive that's just his VO2 MAX. Basically, since there is less oxygen at higher altitudes, it'll obviously be harder for him to breathe, causing him to get tired; especially since he's a younger child too.
So basically, from my knowledge, the best way you can help him is really to increase his VO2 MAX. You can increase VO2 MAX by training or just get use to the altitude with time, so your hemoglobin can produce more red-blood-cells to carry oxygen to the lungs.
*VO2 MAX: maximum oxygen uptake
Last edited by FoShizzle; 01-14-2010 at 10:37 PM.