im in a not too uncommon position now a days. i have a knee and an ankle that i have blown out snowboarding and playing football respectively (played line in high school and planted my foot with the upside facing down.. 180 degrees back.. no more football ).
now i dont mind running and have gotten to be a very good one before, especially when i switched to basketball. however the surface i run on is very important.. wood floors (ala basketball) and grass is no problem. concrete on the other hand is not fun (get pain and swelling after a few times).
now, i live downtown in the city. and since im in university, i cant afford a real gym so i go to my school gym. which is ok (although busy) but since there is no football or soccer field at my school all i have to run on is an indoor track around the gym.. which is concrete. being in the city, its all concrete sidewalks too.
so what are my alternatives for performing HIIT that u guys have found particularly effective. cardio equipment my school has is:
step machines (of course)
bikes (not good for HIIT)
tread mills (which are old and have a ridiculously short stride)
and a pool