Zone 3 is kind of like the goldilocks of run training: It’s not too fast and not too slow. Instead, it’s an in-between effort often described as “comfortably hard.” “Zone 3 training is great,” Brant ...

Natalie Rose, a U.K.-based certified personal trainer, and barre and Pilates instructor, created the 3-2-8 program. She explains the basics on her website, Bodybybarre, where she also has a 12-week ...