You call that exercise?

He comes home from a round of golf. She comes in from an afternoon of horseback riding. Both feel invigorated. But was it exercise?

Those at the forefront of America’s just-get-moving movement consider just about any activity more vigorous than pushing buttons on the microwave as beneficial.

But for most people -- those with a modicum of stamina -- such leisure and recreational activities probably aren’t enough to build cardiovascular endurance and muscle strength. That takes a bit more work.

“To achieve improvement, you need to overload either your heart or your muscle,” says Melissa Johnson, executive director of the President’s Council on Physical Fitness. Those who already are somewhat active will need to do more than play a round of golf using a golf cart, plant a few bulbs out back or take a trail ride with the horse doing most of the work. As one health expert put it: “Getting fresh air is not the same as getting exercise.”

Moreover, it’s not just what you do but how you do it that counts. Exertion levels within one sport can range dramatically, as the following calorie statistics from the American College of Sports Medicine demonstrate. Calories burned is a good measure of effort, because the more calories you burn per minute, the greater the load you put on your heart and muscles, which builds strength and conditioning:

* A round of golf using a cart burns 246 calories an hour; forgo the cart and carry your clubs and it jumps to 387 calories an hour.

* Riding a bike or paddling a canoe using very light effort burns 211 calories an hour. But bike or canoe vigorously for an hour and you’ll dispense with 739 and 844 calories an hour, respectively.

* Walk at 2 mph, and you expend 176 calories an hour; at 4 mph, you burn 281. A light jog of 5 mph requires 563 calories an hour, while running a 6-minute mile (10 mph) uses 1,126 calories an hour.

* Riding a horse for an hour at a walk burns 176 calories, but ride at a continuous trot or faster and you’ll use up 457.

(These numbers are based on a 150-pound person. A person who weighs less typically will burn fewer calories; someone who weighs more will burn more.)

In some cases, people could do just as well by staying home. Horseback riding at a walk, slow ballroom dancing and walking at 2 mph all burn the same number of calories (176 an hour) as cooking and playing the piano. Working on your car burns as many calories (211 an hour) as sailing, canoeing or riding a bike leisurely. Heck, sitting still burns 85 calories an hour.

Some health experts are afraid the hard truth will discourage people from starting.

“All exercise is good,” says Lou Schuler, coauthor of “The Men’s Health Book of Muscle” (Rodale Press, 2003). “Telling people what they’re doing is no good defeats the purpose and is elitist.” However, he says, “most of the benefits people want to gain from exercise -- the muscle building, aerobic endurance and metabolism boost -- they’re not going to get from gardening.”

So how do you know if your activity qualifies as the kind of “exercise” that builds cardiovascular endurance and muscle? Take an honest look at the intensity. “Of the three aspects of exercise -- duration, frequency and intensity -- intensity is the hardest to measure,” says Donna Polk, an endocrinologist and assistant director of the Preventive and Rehabilitative Cardiac Center at Cedars-Sinai Medical Center. Short of going to an exercise lab for an oxygen uptake test, you can gauge exercise intensity in several ways.

* The talk test. When exercising, you should get to the point where you can still talk but you can’t sing. “If you can read a magazine, you’re definitely not working hard enough,” Polk says. Even better, push yourself to the point where you can’t quite finish a sentence without taking a breath, and try to stay there.

* Check your pulse. Know your maximum target heart rate in beats per minute. (A very rough gauge is 220 minus your age.) Try to exercise so you hit 65% to 75% of that for a sustained period, that is, 30 or more minutes.

* Note your “perceived exertion.” On a scale of 1 to 10, with one being how you feel when sitting and relaxing and 10 when you’re breathless, you should be at a 6 or 7.

* Finally, keep a record. Track whether your program is making a difference by noting real changes. Note your baseline when you start a new program, then see where you are after six weeks. Can you lift more? Can you walk or run faster or farther? Does it take more energy to get your heart rate up? Has your body fat composition changed?

Bottom line: It should feel like work, but it doesn’t have to feel like torture.