For the past 3 weeks, I've been doing the Waterbury Summer project:
http://www.t-nation.com/readTopic.do?id=1140463
It is an excelent program, but I have a problem. 12 years ago, as a mid-distance runner, I developed Ilio-tibial band syndrome -in simple terms, a bung knee. This old injury has flared up again, and I'm afraid to run, in case I make it worse. Is there any kind of HIIT that I can do? Anything aqua is out, as it is too cold for the beach and I am alergic to chlorinated pools.

Do you have access to a gym?

Im not sure how bad exactly your knee is, but the first thing i would try is the cross trainer / rowing machine. These are less stressful on the knees, especially if you emphasise the upper body movement.

if thats no good - if the gym has got punching bags, stand stationary and look up some bag drills. This is a great cardio workout. Some gyms also have an eliptical type machine that you sit on but dont move your legs, you just do the upper body arm movement. If you can find one of these it would be ideal for you.

If all that fails, you can pick up some light weights and do a circuit training type workout, which seems like what the waterbury project is.

hope this helps!

Thanks, Carl. I thought the rowing machine might be a good option. It'll help me with my upper body too, which has always been weak in comparison to my legs (like many women.)
I just hope this knee doesn't stop me from quallifying as a personal trainer in the prescribed 8 weeks. My local gym is particularly short staffed and there is an opening there for me, uopn completion of the course.
Edited to say that my knee is not so bad. I am no longer a silly 19YO, who just straps it up and goes right on running. Last time, it ended up so bad, that I had to go for moths without running or squats. I lost an inch off each thigh and I'm pretty sure it wasn't fat.

I dont know too much about being a personal trainer, but surely your health condition doesnt have anything to do with qualifying?

hope it gets better soon!

Actuyally, we are required to pass a series of physical tests, which involve barbell squatting and running, amongst others. There is an option of doing these later, once my knee has recovered, but that means waiting longer to get certified.

aww that sucks! Is there any kind of therapy you can get to help? physio / chiro etc? have you tried using a knee support?

Im assuming you have already looked into it, but for others looking at this thread this link has tons of info:

http://en.wikipedia.org/wiki/Iliotibial_band_syndrome

Im also assuming yours is pretty severe if its lasted years, have you looked into medical help, possibly surgery? Im kinda worried now as i have been getting slight knee pains for a while now!