A:  On one hand, a light cardio session can help with clearing lactic acid and soreness, so it aids recovery in that way. However, if you're going to do fat burning, high intensity stuff, you're going to tax your legs. Plus, if you do your leg workout right, can you even walk? Well, some feel more of the burn the day after, but if you train your legs to total failure and exhaustion, you will only feel like cycling the couch. But pushing yourself mentally, provided it isn't a heavy session of cardio, is probably smart. Personally though, for fat burning - doing it correctly anyhow... which is the only way to do anything or you're wasting your efforts - is for days off. We think recovery is MUCH more important. Here are some other ideas: On your last leg workout, such as extensions, run a set of stairs and then rest and repeat. Or do some plyo kicks or jumps or box work. This can be fat burning too, remember, and it's part of your workout and intensity level DURING training. Might try interval train, with short burst of effort, during the week, but not on the same day as a leg workout for max muscle growth.  Are you!