Unlike the pushup, or the familiar act of walking, jumping jacks are resistant to a romanticized treatment. Flailing one’s arms and legs is just too juvenile—too third grade physical education class—to be recast as a plausible adult exercise. And yet, my experience tells me otherwise. Fifty jumping jacks, executed at a proper clip, raises the heart rate and taxes the arms and legs. I’ve also witnessed otherwise decent youth athletes incapable of correctly doing even a few jumping jacks. It’s a matter of coordination, I’ve noticed.

Even without that obnoxious word’s most common compound qualifier—hand-eye—many of us are sent reeling back to adolescent gym class upon hearing it, and, depending on our experiences while there, either delighted to be free of math and spelling or nauseated with terror. Unlike later athletics, gym class was never a proving ground for real competition; it is instead a laboratory where natural facility is laid bare, and where the first glimpses of future ability are revealed. Some children naturally move their appendages through space, finding fluidity and rhythm once a ball is introduced. But it is here too that a less welcome discovery is made. For every natural, three others struggle against the very framework of our reality. Gravity becomes a demon, and space and time bedevil all effort. Discouraged in youth, many have grown to adulthood quite happy to be free of the burden, and while enough coordination naturally manifests to get most of us through an ordinary day without calamity, I often wonder what a more developed sense of coordination could do for even the most two-left-footed amongst us. Anyway, whoever said old dogs can’t learn new tricks?

Done correctly, jumping jacks require balance, timing, rhythm and effort—the sum of which is coordination. The familiar movement is as follows: Beginning with feet together and arms at the sides (also know as standing), jump. While airborne, laterally open legs greater than shoulder width. Simultaneously, and with minimal bending of elbows, raise arms from side in a sweeping arch above the head. They should graze at the apex. Land in this open position. Jump once more, this time returning legs and arms to starting position. Repeat.

What makes the movement challenging for some is timing. An errant arm or a leg out of syncopation throws off balance in an instant, which, once lost, is difficult to regain. As the benefit of the exercise occurs only after fifty or so are done at a good pace, establishing a rhythm is essential. This takes physical effort, but a surprising degree of concentration as well. I’m not sure if jumping jacks sharpen the mind as well as they tone the calves, but effort no less. I suppose if the advanced among us wish to increase the mental strain they might try counting in prime numbers (one through two hundred twenty-seven would be fifty).

Skeptics—which advocating jumping jacks always seems to attract—are usually mollified when challenged to do ten jumping jacks with one arm secured behind the back. Actually this is an interesting variant for those who master the basic jumping jack as removing a limb from the equation requires additional balance and unusual effort from the trunk. So unusual, in fact, I’d wager even polished athletes might be reminded of their less auspicious beginnings in third grade gym class. For if there is one aspect unique to coordination, it is that it can always be sharpened.