Hey guys, we have a confession to make: We really don’t know why muscles grow how they do—in fact, no one does.

The best that science has done thus far is to show us a number of training and nutrition approaches that are “associated” with muscle growth. It’s a constantly evolving field, and that’s how we’re able to develop new and different—and increasingly effective—workouts each month.

This month’s arm workout, however, is more of a best of. You’ll find a mashup of several of the most reliable muscle-building strategies, fused together into one surprisingly simple workout with a specific focus on building your arms like never before.

How it works

The main way we know to build muscle is by lifting heavy weights, but we assume you’ve done enough of that already; and if your arms are still skinny, you need to try another method.

One of these is focusing on the eccentric (lowering) portion of a rep, which causes more damage to the muscle (a necessary component of making it grow) and is associated with greater rebuilding of that muscle. Another is isometric holds—stopping at the hardest point in a rep’s range of motion. Finally, there’s volume: Lots of sets and reps have been shown to exhaust the muscles like nothing else and force them to grow. Hey, we can’t explain exactly why it works, but at least we know it does.

Directions

Complete the workout once per week, resting at least a day before and after any other upper-body training. Perform the pairs (marked “A” and “B”) as supersets: You’ll do one set of A, then a set of B, rest, then repeat until all the prescribed sets are done. Perform exercises 3 and 4 as conventional straight sets.

For more arms workouts:

Check out the 30 best arm exercises of all timethe sleeve-splitting arms workout, and 10 explosive arm workouts.

For a complete archive of our daily quick-hit routines, go to mensfitness.com/todaysworkout.