New Delhi, Aug. 23 -- Your fitness journey is a kind of perpetual education-in new exercises, new equipment, and keeping track of your goals and how to achieve them. In fact, you have to constantly learn terms that are of zero use to you outside of a gym. And as your goals and exercises keep changing, you need to keep track of that as well. But it's a fun kind of study, where you move and sweat and feel your body get stronger.

And so, it's time to introduce two new terms to that ever-growing list. I wrote a story last week on the single leg RDL and its benefits and variations: of which are many because it is a unilateral exercise. But the one thing about these one-sided exercises that confuses even the most experienced gym-goers is which...