To be honest, I have yet to find a quality mass gainer on the market. The problem with most mass gainers is that they are loaded with cheap sugars as a carb source. Not only can this lead to greater fat gain, it can make drinking them several times a day unhealthy.
Mechanical stress: physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion.
mechanical. 1  having to do with machinery: a mechanical failure. 2  being a machine; operated by machinery: a mechanical toy. 3  caused by or derived from machinery: mechanical propulsion. 4  using machine parts only. 5  brought about by friction, abrasion, etc.: a mechanical bond between stones; mechanical erosion.