Exercise gear: Resistance cord workouts Home workout products made of resistance cords, including stretchy rubber tubing and retractable nylon cables, usually don't get much respect from hard-core fitness freaks. The innovative products below could change that. Often inexpensive and portable, they get the job done and would complement anyone's normal 20-mile run and super-set dead-lift session. Knockout workout Perfect Punch: Padded mixed martial arts fighting gloves attached to a rubber stretch cord that drapes behind your back and adds resistance to all punches. The device is held in place by an unobtrusive padded strap. Likes: Like boxing itself, this is a fantastic upper body and core workout. The product is simple, cheap and effective. Celebrity MMA trainer and TV football analyst Jay Glazer designed them and leads the excellent accompanying DVD workouts; these are good skill-builders that teach you how to throws jabs and hooks and use your hips to generate force. I will not travel without this item. Dislikes: Trying to swap out the regular resistance cord for the denser, heavy-duty cord that also comes with the gloves is near impossible (I gave up). But the regular cord works fine anyway. Price: $29.95. http://www.punching.com Balancing act CoreBody Reformer: A padded cylinder, 3.5 feet long and 6.5 inches in diameter, with a crossbar at one end holding two retractable resistance cords that are designed to work core muscles and balance. Likes: A surprisingly satisfying workout. Lying and standing on the cylinder during the exercises adds a struggle for balance that multiplies the cords' resistance effect. It's designed for women, but I did not feel shortchanged and definitely felt it the next day. Two rubber cradles stabilize it on the floor. The crossbar slides into the cylinder when you're done. The four-workout DVD keeps you moving. Dislikes: Though portable, it's as heavy as a log and cumbersome to carry, even with the strap that's included. Price: $249. (800) 679-3698; http://www.corebodyreformer.com Core and more Core Transformer: A long rubber stretch cord with built-in handles and foot straps that provides resistance through every movement. Designed by veteran L.A. trainer-to-the-stars Linda LaRue. Likes: Easy but exhausting workouts. Crossing the cords in an X with your hands and feet in the straps forces you to engage every plane of motion, getting significant resistance through a variety of floor exercises - invisible ball throws, starfish squats, cross-country skiing, figure-eights, boxing, etc. Workouts conclude with mat exercises and stretching. Simple, effective and inexpensive, it weighs about 7 ounces and fits into a sock. The DVD includes 30- and 15-minute workouts. Dislikes: None. Price: $34.95. (310) 890-3305; http://www.coretransformer.com High times Sklz Hopz Vertical Leap Trainer: Two rubber resistance tubes stretched between a waistband and ankle cuffs that make it harder to extend your leg, in theory helping to develop the explosive leg and core strength that will let you jump higher. Likes: It's easy to put on and instantly makes leg straightening from a bent-knee position more difficult, definitely working the quadriceps. After four jumping exercises (broad-, box- and two squat-jumps) and walking the dog in it for 15 minutes, my legs had been so worked that I couldn't pick up my feet well, skidding them along the ground. I could see how these drills, done regularly, might be worth it for basketballers, volleyballers and anyone interested in gaining more explosive fitness and leaping ability. Dislikes: No DVD included; must access exercise videos at http://www.sklz.com/athletic-performance/vertical-leap/hopz. And I still can't dunk. Price: $59.99. Wallack is the coauthor of "Barefoot Running Step by Step" and "Bike for Life: How to Ride to 100."