You tried running but got sore knees and were chased by mean little mutts slobbering after your ankles. You jiggled to Jane Fonda's videos, but your VCR still works better than you do. You pumped hydraulics at the newly opened spa but left without joining because it was cheaper to buy a new body. You've exercised in fits and starts and dieted off the same 10 pounds for years, and you're still out of shape and feeling guilty. Really, you wonder, why can't somebody come up with a practical low-tech shortcut to fitness?

Well, somebody has. It's a system that should have provoked a revolution in the way Americans exercise, yet not enough people are paying attention. Maybe that's because it's not a glitzy computer-driven system or robotic coaches warbling encouragement in synthetic voices.

Americans love gadgets and are especially drawn, however fickle their passion, to gizmos promising instant, glowing health. In their costly search for the Holy Grail of easy weight loss and physical fitness, they buy everything from overpriced rubber cable exercisers that hook over doorknobs ("melts pounds off like butter") to diode-encrusted electronic exerbikes ("pedal to Olympic fitness in your bedroom"). Most of the stuff eventually winds up at a garage sale.

But at least one exercise system is extraordinarily simple, costs about $20 to get started and really delivers what it promises. It's called Heavyhands, developed by Dr. Leonard Schwartz, and was first introduced nationally in 1982. At first glance, there's nothing very techie about it, but in this case looks are deceptive. There's actually a great deal of applied science behind Heavyhands that goes unnoticed because the system is elegant and streamlined, based on what Schwartz believes is a fundamental fact: The more muscles you use, the bigger the demand on your cardiovascular system, and the more calories you burn.

That's why the athletes with the greatest aerobic capacity are typically rowers and cross-country skiers. Both sports use the arms and legs in concert, distributing the workload over a large muscle mass. Running, walking and cycling work muscles primarily in the lower body, taking arm and back muscles along for the ride while leaving them virtually untrained. Swimming is an excellent activity, involving many muscles, but most people can't afford the time or money to visit a pool thrice-weekly.

In creating Heavyhands, Schwartz developed a system with the cardiovascular, strength-building and calorie-burning benefits of rowing and Nordic skiing (whole-body involvement and high workloads) and the simplicity of walking (minimal equipment), yet free of the impediments associated with many exercise systems (expense and inconvenience).

Heavyhands uses a deceptively simple tool: Strapped, foam-padded handles that look like dumbbells but slip over the backs of the hands. Each handle accepts screw-on weights from two to 10 pounds.

The basic Heavyhands technique is walking while "jumping" the hand weights to various heights. Sounds awkward in print but it isn't in practice because swinging your arms while walking is a natural movement. Heavyhands merely has you swing or pump your hands higher than normal -- bringing them level with your waist, shoulders or ears as you stride. The higher you pump, the greater the work and caloric consumption.

Walking for exercise has become the latest fitness craze, a reaction, perhaps, to running's high dropout and injury rate. While regular walking is a good aerobic pursuit if you go fast and far enough, it hardly compares to Heavyhands walking. Stride without weights at 3.5 mph (not a blazing clip), and you'll burn about 300 calories per hour. You'd have to walk 12 hours to burn a pound of fat.

But if you walked that same pace while pumping a two-pound weight in each hand (level with the top of your head), you'd burn about 780 calories an hour, consuming a pound of fat in 4.6 hours of striding. Pumping hand weights that long at that height could get monotonous, so it's fortunate Heavyhands is a system rather than a single exercise. You can, for example, do a variety of arm and leg movements while walking: punching, flinging, swinging and kicking. You can also do Heavyhands indoors in a small space, where arm and leg movements become a virtually no-impact form of aerobic dance capable of strokin' and smokin' calories away at a record clip.

Leonard Schwartz is a good example of what this low-tech exercise program can produce. A psychiatrist who led a largely sedentary life, he had never run 300 yards until he was near 50 ("If I hit a triple in softball, I was in trouble"). Fear of heart disease got him jogging, and two years later his resting pulse had dropped from 80 to 60 beats per minute. But in 1976, after he pulled a hamstring muscle and was reluctant to abandon jogging, he wondered if slower walking while pumping five-pound weights would keep his pulse high and his leg pain-free. Weighted walking slowed his pace from an eight- to a 12-minute mile, but Schwartz was delighted to see his heart rate and workload remain high. Ever the scientist, he validated his experience, measuring his oxygen intake while pumping and walking on a physiology lab treadmill.

Over the next decade, Schwartz added other exercises to basic pump 'n' walk. He continued lab research into the strength-endurance benefits of working the arms and legs simultaneously, what he dubs "panaerobics." He also wrote two books, the latest of which is Heavyhands Walking (Rodale Press, $12.95).

Today, at 63, Schwartz has a resting pulse of 35, 3 percent to 5 percent body fat (19 percent is average for males) and an aerobic capacity at least as large as most 20-year-old elite athletes' (which Schwartz has demonstrated during testing at the University of Pittsburgh's Human Energy Laboratory).

But if Heavyhands is such an effective method for burning fat and building cardiovascular capacity, why aren't more people doing it? One reason is that it's hard to believe hefting little weights can deliver such a variable workload -- from mild sweat to lung-burning oxygen debt. Another is that many people are embarrassed to walk while pumping mini-dumbbells. (Merely carrying weights doesn't produce any benefits.)

Perhaps the major reason Heavyhands isn't sweeping the country is because the so-called fitness movement is more talk than substance. The majority of Americans are still sedentary. Never mind that Heavyhands is practical, applied science that fits in the palms of your hands. Most folks would rather wait for shiny gadgets promising to magically incinerate fatty tissue while they eat chocolate chip cookies and watch TV. They're going to have a very long wait. ::