Many people have low-back problems. According to national statistics chiropractor Brant Koenig shared with me, "80 percent of Americans will develop a debilitating back injury in their lifetime.” A better understanding of the body can help prevent low-back problems.

The spine is made of a series of links called vertebrae, each separated by sponge-like discs that provide a cushion. These shock absorbers require an even distribution of pressure from the back, front and side. Many times I have heard personal trainers say, "Keep your back flat.” I cringe when I hear that, because, as I tell trainers in courses on the subject that I conduct for the National Fitness Professionals Association, the spine is supposed to curve slightly. Excessive sway in the back is known as lordosis.

The pelvis is tilted, too, which adds pressure to the posterior portion of the vertebrae. A common back problem, often seen in people who slump their shoulders forward and flatten or even round their lower back, develops when the pelvis is in a posterior tilt. When this condition becomes chronic, it is known as kyphosis.

This forces the lower spine to push back, increasing pressure on the front of the spine and on the sacrum, Koenig said. This condition can result from everyday practices, such as what I am doing as I type this column: sitting at my desk with head forward, back rounded and shoulders forward, rather than sitting upright and keeping my neck neutral. Little things make a difference.

The previous are "everyday” back-health issues. Exercise — specifically athletics and the back squat — also can create extreme examples of low-back problems. The back squat is considered the king of leg exercises. It also works the low back and core.

Back injuries occur with the squat when you go too low. Coaches generally teach athletes to squat until the quadriceps (top of the thigh) are parallel to the ground, the standard required in powerlifting events.

Of course, everyone is not built the same. That's why powerlifting champions tend to have certain natural body types. The squat can be a problem for others with different body types, so a one-depth-fits-all principle is not safe.

Some people will use their back more than others when they bring their quadriceps parallel to the ground to keep the bar's center of gravity over the ankles. A "long-torso” athlete with relatively short thighs will likely be able to hit that "parallel.” That athlete is able to stay more upright and keep the normal arch in the back. However, a long-legged, short-torsoed, taller athlete has to bend more at the waist to protect the knees, which should never travel forward past the toes.

Such athletes can injure the back if they strive for the "quadriceps parallel to the ground” position. So, squat depth should be relative to the body type, biomechanics and goals.

Many orthopedic doctors and chiropractors have told me they have seen many patients with bulging discs because of the squat-depth issue. Koenig, a former certified personal trainer, says it is a growing problem.

Some coaches say development of the hamstrings and glutes will result if the parallel squat is not used. But if the back rounds, the squat ceases being beneficial because the spine is taking the added pressure, not the glutes. And how effective can any athlete be with bulging discs?

Get educated. Don't do it just because everyone said so. I have lifted for 19 years and participated in many sports, including competitive body building, without low-back problems. I want young athletes to have the same success and longevity.

A healthy low back also requires strong abdominal muscles, which secures the spine. Always lift with your tummy tight and perform direct abdominal exercises every other day. Another way to prevent low-back problems is to stay flexible in your legs and hips — the hamstrings in particular.

I suggest getting a comprehensive stretching routine from a physical therapist, chiropractor, orthopedist or well-educated personal trainer.

Protect your low back.

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