After reading this forum last night, I started a modified type of guerilla/tabata/HIIT training tonight. After some brisk walking to warm up for about 2 miles, i found a slightly graded hill. In both hands i carried a 2lbs dumbell. I sprinted up the hill while pumping my arms as hard as i could. I estimate the hill took about 20 seconds to get up, and i walked for about a 1.5minutes getting down, then repeated 10 times.
After that i walked up a larger hill for general conditioning. Then found another smaller hill that was long. This time without dumbells, i did a 20 second sprint, and about 10second rest for two reps until i reached the top of the hill, then walked to the bottom for about 3 minutes or so. Then repeated it once more.
I had originally planned on going to the gym after this, but I was pretty much done after that. I'll definitely try to keep it up.
I think it's probably good for high level cardio/combat conditioning. But you still cannot neglect mid and low level conditioning. Which could very well be of a low impact nature. Just something similar to a brisk 2 mile walk or walk/slow jog on occassion. Along with some eliptical and other forms of weight training and plyometrics for strength, etc.