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.
Strain = A change in shape or volume in response to a stress. Stress is the cause, strain is the effect! There are three types of stress: 1) Compressive stress  Forces that squeeze or push toward one another from opposite directions (cause shortening or flattening). 2) Tensional stress  Forces that pull away from one another in opposite directions (cause stretching or extension). 3) Shear stress  Forces that are offset from one another and operate in opposite directions (cause a shear strain). The behavior of rock during stress depends on: 1) The type of rock. 2) The type and amount of stress.