I must start by saying that there is no workout that can be regarded as a 'bad' workout and you should avoid it because it will bulk you up. It all depends on how much you keep doing it and what muscles are mostly used. In today's blog post, let's talk about the kind of workouts that when overdone are likely to add muscle. Squats Lunges High Knees Traditional HIIT(that which includes loads of jumping) Running up a hill Using the elliptical and stair master Lifting heavy weights Jumping rope To know exactly how they add bulk please read this post here A lot of the above workouts focus so much on the quads and hamstrings. They will probably overwork these muscles leading them to grow bigger. Maybe too much than your liking. The key here is not to avoid them but to do them in moderation. If you do a squat as a warmup. Then that is probably not a big problem. If you do HIIT twice a week, that is also acceptable. Want to know which workouts will not bulk you up. Click Here