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.
Lift your hips off the ground, using your abs. Be careful not to push down with your hands, back, or head. If you can't lift your hips using just your abs, you'll need to build more strength with regular crunches. Otherwise, you're just wasting energy while other parts of your body do the work.ips. 1  Crunches are a fun easy way to create flat stomach,hard rock abs and obliques. 2  Women have a greater natural curve in the lower spine than men do, because of the shape of their pelvis.