Twenty years ago, the gurus at the American College of Sports Medicine told us to get off our duffs and get those lungs and hearts pumping. Eight years ago, they told us to pump iron, too.
Now, they’ve added a third cornerstone to their fitness guidelines — get flexible.
Don’t groan; it’s long overdue. And while stretching is an addition to, not a substitute for, the aerobic exercise and weight lifting we should already be doing for health and fitness, it’s arguably the easiest and most enjoyable exercise of the lot.
And if it’s just looser limbs or a better golf swing you’re after — as opposed to yoga-like inner peace — you can even do your stretches while doing something else, like watching TV.
In case you haven’t noticed, one of the less pleasant features of aging is that creakiness called decreased range of motion. If you can’t move your limbs, head, and trunk through a full range of motion, exercise physiologists say, you’re setting yourself up for orthopedic problems, including low back pain and injury.
It’s also just plain demoralizing if your shoulders get so tight that brushing your hair becomes an Olympic event or your hamstrings become so taut the mere words “bend over and touch your toes” send you back to the couch for another decade.
The solution, the sports medicine folks declared several weeks ago, is flexibility training.
For the record, there are no clinical studies proving the benefits of flexibility training. In fact, compared to the data on aerobic exercise and strength training, the data on flexibility is scant, says William Evans, director of the nutrition metabolism and exercise program at the University of Arkansas Medical School.
But studies are piling up fast enough to justify adding flexibility training to the standard fitness regimen, says Glenn A. Gaesser, an exercise physiologist at the University of Virginia and a co-author of the new guidelines.
For one thing, it’s clear that connective tissue benefits from stretching — or at least suffers from lack of it. In women who wear high heeled shoes, tendons, ligaments — and muscles — become so shortened that walking uphill may produce cramps or injuries to calf muscles.
For another, it’s been demonstrated many times in animals that stretching a muscle triggers growth factors that increase the number of tiny, contractile protein filaments inside each muscle cell.
These actin and myosin filaments slide over each other or pull apart, grabbing on to (“cross-linking”) each other at intervals. This lets the muscle cell contract or extent with controlled ratcheting action.
Muscle cells also have mechanisms called spindle receptors that sense where the muscle is in space and how much tension — or muscle tone — it has. When you stretch a muscle suddenly, or too far, these receptors send out an alarm, telling the muscle to contract immediately to protect itself against injury.
But if you stretch carefully, you can train these receptors to pause before firing, allowing the muscle to get longer — grow — without reflexively tightening.
Muscle physiologists have identified three kinds of stretches: static, ballistic, and PNF, or proprioceptive neuromuscular facilitation.
Ballistic stretches, in which you bob or bounce while trying to do something like touch your toes, are not widely recommended because they can cause muscle injury.
But static stretches are safe. It’s a static stretch if you sit on the floor with your legs extended and slowly try to touch your toes, holding the stretch 10 to 30 seconds.
PNF stretches are also safe, but are more complicated and often require a partner. For instance, as you sit on the floor with your legs extended, your partner pushes on your back while you push against him, contracting your muscles for about six seconds. Then you do a static forward stretch for 10 to 30 seconds.
The idea is that by contracting your muscles first, you re-set the firing threshold of the stretch receptors in muscle fibers so that it takes more stretch to make them fire.
Not all exercise physiologists use PNF stretches in their practice, in part because they believe static stretches are almost as effective.
Some gurus swear by yoga as the best approach to stretching, and yoga is “an excellent way to develop flexibility,” says James Graves, chairman of the exercise science department at Syracuse University.
But it’s not the only approach, and a simple 20-minute routine that stretches major muscle groups two to three days a week also works fine. It’s also best to stretch after your muscles are already warmed up.
If you want to try yoga, shop around for a teacher you like, advises Betsey Downing, a sports psychologist who runs the Health Advantage Yoga and Personal Development Center in Herndon, Va.
A good teacher, she says, is one who knows anatomy and can offer precautions and alternative stretches if you have an injury or problem doing a particular move.
There’s no universally-accepted certification program for yoga teachers, so it makes more sense to ask a teacher about his or her experience and approach — there are dozens of varieties of yoga — than about credentials per se.
And beware of teachers, and stretches, that cause pain. It’s fine to feel that your muscles are working. But sharp pain — particularly in the joints or at the points where the muscle attaches into the bone — is a sign of injury, not progress.
SIDEBAR:
What it takes to be fit:
When the federal government issued its 1995 exercise guidelines, it had the modest goal of lowering people’s risk for chronic conditions like hypertension and diabetes. The American College of Sports Medicine guidelines have a more ambitious goal: fitness.
The feds call for accumulating at least 30 minutes of moderate activity on most days. This means you can add up a 10-minute walk, 10 minutes of gardening, 10 minutes of chasing the kids around the playground.
The sports medicine guidelines are tougher — aerobic workouts of less than 20 minutes don’t even count.
And while the feds focus on mild aerobic exercise, the sports medicine group recommends aerobics plus strength training and, as of a few weeks ago, flexibility training as well. You can do the minimum level of all three in roughly three hours a week.
For overall fitness, here’s what they recommend:
- Frequency — 3 to 5 workouts a week. Fewer than three won’t be enough, more than five will add little.
- Intensity. The goal is to work fairly hard, at 55 to 90 percent of your maximum heart rate. To estimate this, subtract your age from 220. If you’re 50, this yields 170. If you want to work out at 75 percent of your max, multiple 170 by 75 percent, which gives 128 beats per minute.
- Duration. Workouts should last 20 to 60 minutes.
If you must cut corners on aerobics, sacrifice duration first; for example, chopping a 40 minute workout to 30. If you have to cut more corners, sacrifice frequency; drop from five days a week to three or four. Don’t sacrifice intensity.
For instance, to work the quadriceps, the big muscles in the front of the thigh, do knee extensions (sit in a chair and lift the foot against resistance, either a weight or a machine).
Other major muscle groups to work include the hamstrings, abdominals (that means bent-leg sit ups), chest presses (push ups or bench presses) and rowing-type exercise in which you use the upper body to pull weight toward you.
You also need to work the back muscles, either pushing up against a machine or lying on your belly, hooking your feet under the bed, and arching up so your chest is off the floor.
For arms, try biceps curls and triceps manoevers (hold a weight in your hand with your arm straight up over your head; bend your elbow so your hand brushes your shoulder; then extend it up.)