"The worst case of fatigue loading is the case known as fully-reversing load. One cycle of this type of fatigue loading occurs when a tensile stress of some value is applied to an unloaded part and then released, then a compressive stress of the same value is applied and released."


http://www.epi-eng.com/mechanical_engineering_basics/fatigue_in_metals.htm

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.