You'd think by now America's assorted fitness celebrities would know how to teach a safe exercise. For a decade they've been hopping around in spandex and designer sneakers, talking about muscle tone and body alignment so much that -- well, put it this way: Those of us who want to injure ourselves can do it skiing or playing tennis or even shoveling snow. But who needs to collapse in pain while following some perky exercise tape? Nobody. There's no dignity in that.
Still, exercise physiologists shake their heads at some of the moves being passed off as healthy. "The problem is that any celebrity can decide to make an exercise video," says Peg Jordan, a nurse and the editor of American Fitness, the magazine of the Aerobics and Fitness Association, which certifies aerobics instructors. "So you get people who may not know anything about how to protect the back and knees against injury."
Jane Fonda's first video, released in 1981, earned the name "Pain Fonda" because it featured moves that not only burned but could lead to injuries. Most video instruction, including Ms. Fonda's, now seems rooted in the knowledge that viewers should be handled with care. Eighty percent of Americans over 30 have suffered back pain, 20 percent have had knee problems, and not everybody looks terrific in tights. These instructors avoid the many old gym class drills that, even when done up as !B modern aerobic-dance moves, are potentially harmful, if not useless.
But Ms. Jordan and others still are having to skewer dozens of fitness stars for neglecting safety. Among the most prominent are Jake Steinfeld, the affable, pump-you-up host of ESPN's "Body by Jake," and model Cindy Crawford, whose video topped best-seller lists for months. These two, among others, revive a range of risky techniques. Everybody throws out blanket cautions of some kind -- "Check with your doctor," "Go at your own pace," and the crucial "Keep breathing" -- but many neglect to mention more useful warnings. Namely:
* Save your neck: The tip of the spinal column and the muscles that surround it already spend all day lifting, turning and supporting the head, which is why many aerobics teachers have given up neck circles, in which you drop your head to one shoulder and let it roll across your chest and back around, like a rag doll's.
Jake makes this exercise look strenuous, and Cindy makes it look sensuous. What it really is, says Ms. Jordan, is pointless. "If you want to stretch your neck," she says, "drop your chin to your chest, slowly; then tip your head back, then to one side and the other."
Think of the spinal column as a stack of tea saucers separated by jelly doughnuts. When you're young, these cartilage-filled doughnuts, or disks, are springy, the neck muscles and ligaments supple, and the spine itself strong. But as you age, the ligaments become more likely to rupture, causing a sprained neck, while the disks can bulge or burst.
Thus beware the yoga plow, in which you lie on your back and lift your legs up overhead and then lower them behind your head. "You've got your whole weight on the top of your spine," says Daniel Kosich, a Denver-based physician with a sports medicine practice. He suggests a less risky way to stretch: From the flat-back position, simply pull one knee to your chest and briefly hold. Do that several times with each leg and then with both legs together.
* Get off your knees: Year after year the knee becomes measurably more fragile; in particular, the fibrous ligaments that hold the kneecap in place and directly connect the thigh and shin bones can fray like old rubber bands if twisted or stretched too far. The resulting injuries range from a simple ligament sprain, which can put you in a knee brace for months, to a tear, which can require surgery.
"Sometimes I see people on their knees, sitting on their ankles, and then even leaning their head back toward the floor," says Robert Stephens, an anatomist at the University of Health Sciences in Kansas City, Mo. "This strains the cartilage and the ligaments that run across the front of the knees. Not a good idea."
The same goes for the hurdler's stretch, in which you sit on the floor with one leg kicked straight forward and the other tucked back behind your rump, then lean forward and touch your toes -- like Jake does. "In this exercise you're twisting and overstretching the knee ligaments of the leg you tuck behind," says Ms. Jordan. A safer way to loosen the hamstrings, she says, is to lie on your back with your knees slightly bent and gradually raise one leg, keeping it straight but relaxed, until the foot is directly above your chest. Now reach up with both hands and slowly pull the leg toward you as if to get a closer look.
Deep knee bends, thigh exercises requiring you to drop into a full squat and push yourself back up, break all the rules. Not only are you pulling the knee ligaments taut, but you're invariably bouncing down, which gives an extra tug. This can turn a stretch into a ligament tear, and a mild tear into a severe one. Only dinosaur gym coaches still recommend these. Physiologists are suspicious of anything resembling full squats.
In Ms. Crawford's video, the star does shallow squats, bending her knees just halfway before pushing back up. "This is safer," Ms. Jordan says, "but Cindy bends her knees way in front of her toes, which strains the knee ligaments badly." Instead, rest your back against a wall and shift your feet away from the wall. Now, with your arms extended straight in front of you, gradually slide your back down the wall until you're not quite in a sitting position, then push back up again. "Your knees," says Ms. Jordan, "should always be directly over your feet."
* Watch your back: The lower back can betray you at the drop of a hat -- literally. Every time you bend over, the stack of vertebrae bows forward, pinching the disks at the front of the column, especially where the spine bends most sharply, in the lower back. Disks there are the first to show wear and the easiest to rupture.
"One of the worst things you can do to your disks," says Peter Francis, an exercise biomechanist at the University of San Diego, "is bend over and twist the lower back." Doing windmills, for instance, you lean over from the waist, swing your right hand down to touch your left foot, then vice versa. In this way, millions of people, including Jake and President Clinton, give their disks a dangerous mashing while warming up.
For a gentler way to loosen the legs, prop yourself against a wall face forward, palms extended for support, as if you're being frisked. Slide one foot a few inches behind the other, then lean into the wall, keeping the back leg straight and feeling the muscles there lengthen.
Even old-fashioned toe touches pinch the lower back disks unnecessarily, especially if you lock your legs straight. "Flexing the knees a little is much better," says Peg Jordan. "Then bend over slowly and let your arms hang."
An oft-used exercise for abdominal muscles, and a staple of Jake's routine, is the double leg lift, done while lying on your back, legs held straight out about six inches off the ground. From this position Jake has his disciples move their legs in a scissors motion. This exercise actually is nearly useless for the stomach, as it mostly uses strands of thigh muscle connected to the hip that are already plenty strong from walking, standing, even sitting. Also, the move freezes your lower spine in an uncomfortably arched position, so you risk straining lower back ligaments and muscles. The same goes for straight leg sit-ups, which are fast going the way of wooden tennis rackets.
For a better stomach workout, lie on your back with knees bent, your feet and lower back flat on the floor, and your arms loosely folded across your upper chest.
Now raise your head, neck, and shoulders off the floor, keeping your lower back flat; hold for a few beats, then relax.