HERE'S HOW I became an expert on building muscle after 40: I turned 40 (and then 50, but that's a slightly different story). The Facts About Training After 40 for MenErik Isakson // Getty ImagesSarcopenia Is Real—So Build Muscle NowSarcopenia is real. What Works for Men Over 40 to Build Musclesimonkr // Getty ImagesYour journey to 40 is not mine, and mine isn’t yours. That is, you can go inside the muscle and feel how hard it’s working—something you can’t do with a squat or bench press. For almost everyone reading this, it’s much better to use the dumbbell shoulder press and the other overhead lifts in their program.