Pregnancy transforms you, and I say that from (very recent) experience — I just gave birth to my first baby a week ago, and I still marvel at just how much my body has changed these past nine months.

Case in point: You rely on your core muscles to carry you through the miles. And research shows that core strength training can improve the force you put into your steps, your overall energy transfer, ...

The advice is common — and vague. Here’s how to do it properly. By Hilary Achauer When I began weight lifting in my late 30s, my coaches often gave me a somewhat baffling cue. “Engage your core,” they ...