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.
Keep active, unless the pain is really acute.. Keeping your neck warm and semi-supported by a scarf or a roll-neck jumper is also a good idea, says Margo. Gentle rubbing with your fingers is fine, but don't be too hard or go too deep. You can use an anti-inflammatory drug, or a little pain relief. Take what you would take for a headache..