Building up muscle mass is not very difficult for most builders, especially if they work out correctly and hard enough, and consume a lot of healthy food. But mass as a whole should not be mistaken for pure muscle mass! A lot of builders who emphasize too strongly on food, despite its being healthy, store a thick layer of fat under their muscles. Building up pure muscle mass is an entirely different thing! Professionals know how to add muscle mass without fat which makes you look plump and forces you to buy two-size larger jeans!
Three of the champions of nowadays, NASSER EL SOMBATI, MIKE FRANCOIS AND KEVIN LEVRONE, have been discussing how to get your muscles separated and remain firm without losing muscle mass.

6. Include machine and cable handles exercises
Free weights are an important and effective way to build up the muscles of the biceps, yet they are not the only alternative. There exist many productive machines for biceps, produced by companies like Nautilus, Cybex, etc. Do yourself a favor and experiment with all the machines for bending available in the gym. You can be sure to find at least one that works effectively for you - it means you will be actually feeling your biceps work; the pumping up at the end of the series is phenomenal and the next day you will feel slight pain.