HIIT - Body Reaction, How's my schedule?

  • Hello everyone! Sorry this is so long, but I'd appreciate any advice!

    I have about 10 lbs (ambitiously 20) to lose! I hate running because I have a bad back and end up in tons of back and leg pain when running for too long...plus I'm a bit top heavy and it's not exactly comfortable. I am extremely self-conscious about exercising in public, and my time is limited through the day due to job and other commitments, so I've decided to try interval training by alternating sets of 10 burpees with 30 seconds of light jogging around my apartment.

    I've been doing this for 2 weeks, 2-3 times a week and let me tell you, it's been fantastic. While I've only lost about 2 lbs so far (I'm weight training, too) I am already beginning to see fitness gains. At first I could barely squeeze out 4 cycles, now I'm pushing out 6 and plan to keep going until I can do a solid 15 minutes (including warm-up and cool-down). I can take fuller breaths (I'm sure anyone who remembers when they first started cardio after being nearly sedentary probably knows what I mean) and have way more stamina already.

    Perhaps it's too soon to tell but in my past couple of sessions I've been having some trouble. I try to do my HIIT by itself without any weight training, so I usually do something like 2 muscle groups per day for 2 days, then my HIIT, or HIIT one day, then strength training for the next two--I haven't landed on the best cycle (HIIT first after a day of rest, or HIIT THEN a day of rest).

    So basically what has been happening is that my legs will get extremely swollen. I know that there is a plyometric aspect to doing burpees (jumping high into the air from a full squat), and I'm very familiar with the feeling of muscles swelling during the kind of cardio that engages muscle in a high-impact way (I used to be a martial artist, a black-belt in fact, and boy my arms would be huge after banging out 100 push-ups). In my most recent session, after the 6th round my legs felt so tight and swollen that it was difficult and uncomfortable to walk with a normal gait, I was shuffling around my apartment as if I had a peg leg. It was a feeling that I'd never felt before when doing any sort of cardio--it was a little scary. I kept wondering if I had a blood clot in my legs and if the lymph fluid was going to keep building up.

    The swelling subsided within the hour, but I couldn't help wondering if:
    1) I'm working my heart too hard and I wasn't ready for that extra set. I generally feel like dying--heart pounding, lungs burning--whenever I do HIIT, but apparently that's normal ;]
    2) I'm improperly nourished, too few carbs for energy or too high sodium causing me to retain water? My fluid pH not regulating properly due to electrolyte imbalance?
    3) I'm overtraining/pushing myself too hard--I did my leg groups the day before, but I never let mild DOMS stop me from working out.

    Like I said, I didn't die, I was just mildly uncomfortable. The next day I was just as sore as I usually am, not the end of the world. Does anyone have a similar experience? Is it a sign that I should hold back or keep pushing forward with my regimen? Any suggestions on how I should distribute my cardio versus my weight days?