Electrons play many roles in solid materials. When they are weakly bound and able to travel—i.e., mobile—they can enable ...

When we think of lifting heavy weights, we always choose a weight that allows us to only do four to five reps, and when we think of lightweight, we go so light that we can only do 25 or 30 reps.

He gives an example of doing a few sets of weighted pull-ups, pretty close to a 5-rep max before heading back to standard unweighted pull-ups. 'I promise you two things are going to happen,' he says.

I can say from personal experience that not everyone in the gym knows what they’re doing. A lot of them (read: us) haven’t ...