Ok listen up people! If you want to build muscle, do cardio after weight training. If you weight training after cardio, you must wait about 20 min, then weight train. What happens is that if you do cardio first, your heart rate is still up when you weight train, therefore it would be like cardio with resistance, thus your muscles won't get the full benefit from weight training. Your body burns more fat when you weight train, than cardio. Why? Cuz muscle is what burns fat!!!! So when you do weight training, your body is fat burning mode, it will then carry over when you do cardio!