Athletes need to monitor their lifestyle very closely and keep their health conditions at par with their competitors; not just by eating right food items but also by consuming supplements.
Supplements are an integral part of athletes' diet. It is required to have an enhancement of their endurance, and also to increase or, if not increase, at least maintain the appropriate muscle mass to be able to improve size and strength.
One of the most important parts of any sports nutrition is protein supplements. Without these supplements, athletes would not be the way they are at present. However, contrary to what most people think, diets jam-packed with protein do not necessarily build up muscle strength.
Building up muscle strength would be the job of regular physical activity. So if you want those big muscles you have to do exercises, not necessarily at gyms but could be also at your residences, daily. The key factor here is regularity. What you can achieve with steady and regular exercises may not be possible with a high profile but an irregular one.