molecule. 1  Chemistry, Physics. the smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound. 2  Chemistry. a quantity of a substance, the weight of which, measured in any chosen unit, is numerically equal to the molecular weight; gram molecule.
When I do crunches my neck starts to tighten up and it makes me have to rest before doing another set of crunches.
1 The most common reason is to relieve pain. 2  The neck brace helps your neck support the weight of your head while the soft tissues in your neck have a chance to heal. 3  You may need a neck brace after spinal neck surgery to keep your neck bones in line while you heal. The most common reason is to relieve pain. 2  The neck brace helps your neck support the weight of your head while the soft tissues in your neck have a chance to heal. 3  You may need a neck brace after spinal neck surgery to keep your neck bones in line while you heal.