Due to the high stress levels imposed on the knee joints when running HIIT style, I've decided to do my HIIT training on a spinning bike rather than the track. Also, since the boxing class I attend is rather low-impact but highly technical, I'll do the endurance work directly after the class, friday night. Basically, I'll do my HIIT work on a spinning bike, set to moderate resistance. This way, I'll spare my knees. After a short warmup of about 2-3 minutes of low/moderate intensity cycling, I'll do 10 intervals. Note that this training is done after a technical boxing class that takes me about one and a half hours, so I'm pretty much warmed up. Each interval is made up from 60 seconds of low/moderate intensity cycling, followed by 30 seconds of all-out sprinting. Going through my 10 intervals will therefore take me 15 minutes. I'll try and add an additional interval every week, so basically after 10 weeks my working time will be doubled. (Image taken from fl...