it's quite a lot for me 
but probably cuz I dun run as often
Anyway, I suspect it might be from you having done the 100 push
ups, especially if you don't do it often enough (means at least
once to twice of 100 push ups a week)
Probably try stretching the chest by opening your arms wide. Or
you could use the wall.... if you know what I mean... and how to
stretch the muscle there...
If you have a tennis ball, you could probably do with a bit of
SMFR, which could be done on the chest by placing the ball between
the chest muscles and the wall, then "push" yourself hard on the
wall...
actually, i do 50-100 a day lol. i think it's cuz my body
unaccustomed to this kind of exertion. normally i run 2km then go
home liao. crap. here got doctor or not lol
