Former world boxing champ Keith Holmes recognizes a hit when he sees one. So when he came up with the idea for a “resistance shirt,” he knew it could be a knockout.

“Resistance bands are in almost every gym,” the D.C. native says, noting how helpful the stretchy tools are for training. But people frequently have trouble adjusting them, and the bands lying around gym floors don’t always seem sanitary, Holmes adds.

So Holmes asked his dry cleaner to do him a favor: sew a resistance band into the back of a compression shirt and let the ends dangle by his hands. As soon as she delivered it, he slipped his palms into the handles and shadowboxed his way through a jog.

“My muscles were burning,” raves Holmes, who exercised with this prototype for three years, shortening the band and adding padding for comfort. The result is the RS-1 ($100), the first product from Holmes’ apparel company, Ripflexxx. It debuted at last month’s NBC4 Health & Fitness Expo, where Holmes demonstrated how he could jab, hook and uppercut, all with the benefit of 35 pounds of resistance.

Holmes’ sales pitch? The RS-1 is as useful for boxers as it is for mall walkers, or anyone who wants to up the calorie burn of a workout. “Anything with resistance will make you perspire faster,” Holmes says. Good thing the shirt’s machine washable. -Vicky Hallett

Workout notes:

Just getting into the RS-1 was a workout — the tug of the resistance bands forced me to slip into it in one motion, which sounds easy until you try it.

When I wasn’t gripping the handles, they hung close to my elbows, so they weren’t in the way. As soon as I grabbed them, I felt the weight.

My upper arms were exhausted after trying to keep up with Holmes for a bout of treadmill shadowboxing. They got even more of a workout when we hopped off and incorporated the bands into twisting core exercises and pushups.

The shirt turned out to be pretty versatile, and I can truthfully say I didn’t want to take it off. Mostly because I was already sore. -Michael Cunniff