 cardio does not send a muscle building signal cardio sends a build endurance signal and it also burns a lot of calories during the time that you're spent doing it so because it doesn't send a muscle building signal and because it burns a lot of calories the way your body adapts to it is by making you more efficient giving you more endurance but also making more efficient with calorie burn so you end up losing muscle you end up paring muscle down cardio will send a competing signal with the strength training so could you lose more weight on the scale total weight by doing cardio plus weights plus a deficit in calories yes will you lose more fat no will you build muscle definitely not so remember the goal here is to build muscle and burn body fat at the same time you don't want to do anything that could potentially get your body to pair muscle down you want to do everything in your power to try to get your body to build muscle while simultaneously eating in a calorie deficit to burn body fat and if you don't then your body will adapt metabolically by reducing muscle