WHY YOU NEED TO BONE UP...
|March 2004 - Bicycling Magazine
by Roy M. Wallack
Bob Breedlove feels like Superman-except for one thing. The orthopedic surgeon from Des Moines, Iowa, who has set several transcontinental cycling records and raced across the country seven times, has the heart of a racehorse, the squared quads of a professional wrestler, the chiseled torso of a lumberjack, and the appearance and vitality of a man far younger than his 51 years. He also has the low bone density of a man in his 70s and is on the road to osteoporosis.
And he's not alone. New medical evidence seems to indicate that if cycling is the only athletic activity in your life, you might be wasting the foundation of your body-your skeleton-and turning into a broken hip waiting to happen. A study published in the August 2003 issue of Osteoporosis International reports severe bone loss in 27 male racers ages 40 to 60 who'd trained an average of 12.2 hours a week for 20 years. At an average age of 51.2 (when a typical man has no bone loss at all) the cyclists' average hip and bone densities were 10 percent lower than those of a control group of moderately active, non-cycling men of similar age.
"Clinically, 10 percent thinning is significant-not good-almost frightening," says the study's author, Jeanne Nichols, Ph.D., a San Diego State University professor of exercise and nutrition. "Ten percent bone loss today will lead to a much higher than normal fracture risk with age." Translation: The debilitating bone fractures normal men become susceptible to in their 70s and 8Os may happen to these superfit guys in the next few years.
If the idea of fit men with thin bones seems oxymoronic, it may be because osteoporosis is considered an old-ladies' disease. Four out of five victims are women. Men's bones are naturally denser and usually don't show signs of osteoporosis until 20 years later than the average woman's bones, which begin thinning at menopause.
In Nichols' study, however, two-thirds of the cyclists already showed signs of at least osteopenia (moderate bone loss). Four had the severe bone loss of full-blown osteoporosis. Dual X-Ray Absorptiometry (DXA) bone scans of Don Coleman, 42, an amateur racer since his teens, show borderline osteoporosis in his spine-unexpected, given his love of dairy products such as milk, cheese and ice cream. (Calcium is a much-recommended antidote to bone thinning.) Among the worst was 48-year-old, four-time Race Across America competitor Rob Templin. According to figures from the study; the bone densities in his hip and lower spine were equal to those of someone almost twice his age. His condition can be at least partly blamed on his daily habit of drinking one to two liters of cola, which is laden with phosphoric acid, known to leach calcium from bones. Among the most surprised of the test group: Breedlove, who had osteopenia despite a lifelong regimen of weight lifting, another known bone-builder. "I was stunned," says Breedlove, who, in 2002, set the 50-plus age-group record for crossing the country by bike. "I thought I'd test normal. I used to run marathons, have no family history of osteoporosis, eat five helpings of dairy a day, and for decades have been weightlifting three days a week, September through March."
Although Nichols focused exclusively on elite male cyclists, some in the medical and cycling community believe that other cyclists, including elite women as well as recreational riders of both sexes, might not be immune to biking-related bone loss.
Former NORBA star Tammy Jacques, 35, blames her retirement on osteoporosis. Pro mountain biker Sally Warner, 33, a Ph.D. at the University of Washington who last year published a study that showed mountain bikers have denser bones than road-only cyclists, has just 83 percent of the spinal bone mass of a normal female her age.
The most controversial issue is Nichols' opinion that bone thinning goes beyond racers and extreme riders. "A recreational cyclist who rarely does other sports has the bone density of a nonathletic couch potato and is most likely headed for moderate to severe osteoporosis," Nichols says.
None of the bone experts contacted for this story endorsed that conclusion. "This is a good study," says Dr. Felicia Cosman, clinical director of the National Osteoporosis Foundation. "But given that it is not longitudinal [a long-term comparison with several measuring points], includes no dietary assessment and has no similar studies of recreational cyclists or couch potatoes to compare against, you can't extrapolate it to the general cycling population."
The careful accretion of medical consensus is one thing, but logic seems to indicate that there could be some level of risk for tens of thousands of century riders, long-distance tourers, dawn-to-dusk mountain bikers and four-day-a-week Spin-class junkies. "If you're regularly in the saddle for long stretches," says Breedlove, "it makes sense that some of what happened to us could happen to you."
HOW BONE LOSS HAPPENS
Bones typically lose 5-10 percent of their density per year, but when we're young and healthy this is routinely replaced. In a process similar to scoring a wall before plaster is applied, special cells called osteoclasts prep your bones to receive a new layer of calcium, which is put on with other cells called osteoblasts.
As we age, we're able to replace less and less of our lost calcium, although the loss can be slowed or even eliminated by a good diet combined with physical activity that includes impact, G-forces and vibration. That accounts for the extra-thick leg, hip and back bones noted in studies of runners, weight lifters, volleyball and basketball players, and the bone thinning associated with low- or no-gravity activities such as swimming or, to a radical degree, space flight. (You'd have to ride intensely for 100 years to equal the bone damage incurred during a two-month orbit of the earth, according to Nichols.)
Cycling's seated, off-the-ground position, which eliminates weight bearing and impact on the legs, might have a minor positive effect at best. "Heavy tension on the pedals while standing and climbing, especially, probably builds some bone," says Nichols. But that might not be enough to mitigate dietary and hormonal negatives associated with society in general and hard aerobic training specifically. Even if you steered clear of teenage eating disorders, adult lactose intolerance and rabid consumption of soft drinks (all of which lead to bone thinning), your calcium stores still could get hammered by cycling's unique capability for hours of hard training.
Dr. Eric Orwoll, director of the Oregon Health & Science University in Portland and an authority on male osteoporosis, says, "You can speculate all you want about cycling and osteoporosis, but get enough calcium and vitamin D and you're okay"
Getting enough can be difficult for cyclists, however. Let's do some math. According to Dr. Christine Snow, director of the Oregon State University Bone Research Laboratory, an average man engaged in intense training loses 200 milligrams of calcium in sweat per hour. The recommended daily adult calcium intake (which may be upped from 1,000 to 1,200 mg) has enough padding to handle one hour of exercise, she says. A seven-hour century might sweat out 1,400 mg of calcium-more than a day's recommended intake. Averaging 12.2 hours of weekly training, the riders in Nichols' study lost 2,440 mg-two days' worth a week, year after year.
Typical energy drinks contain little, if any, calcium. Unless those cyclists each downed an extra dozen servings of milk or yogurt per week on top of an already healthy diet, the calcium they sweated out could come from only one place: their bones.
Nichols and other bone experts interviewed for this story hadn't included sweat loss as a factor in bone thinning, but there are precedents. Robert Heaney, M.D., a nationally known calcium researcher and professor at Nebraska's Creighton University, cites a 1996 study that documents sweat-loss-induced bone thinning among college basketball players. "But at least they had several factors to help them minimize the loss: weight-bearing vibration to stimulate bone growth and a limited season length," he says. "Cyclists don't have either."
Beyond sweat loss and biking's lack of triggers for bone building, there might be other strikes against cyclists. A 1998 report from the Journal of the American Academy of Orthopedic Surgeons found that female and male endurance athletes may suffer decreased levels of sex hormones, which leads to bone thinning. Orwoll surmises that people who are skinny (another risk factor for osteoporosis) might be drawn to the sport because they succeed in it: "It could be that people who like to do a lot of cycling have less-heavy bones to start with." And, finally, there's the simple bugaboo of time: Hours in the saddle can leave little opportunity or desire for bone-building activities such as weight lifting, basketball or running. "Face it, it is an axiom in bike racing that 'If you're not riding, you're resting,' "says Nichols, a masters cyclist and age-group triathlete.
AND THE VERDICT IS...
Not in yet. "While the evidence is piling up for racers and extreme riders, for recreational riders, we only know that cycling is not as good, bone-wise, as other fitness activities," says Conrad Earnest, Ph.D., director of exercise physiology and resident cycling expert at the Cooper Institute in Dallas. There's no doubt that cycling's short-term and long-range physical, mental and emotional benefits far outweigh the risk of bone loss, especially for recreational riders-keep pedaling, folks-but BICYCLING is sufficiently impressed to recommend action. See "Make Your Bones" (at right).
For Breedlove, the battle continues. He added more weight lifting and calcium (to 2,000 mg a day) during training for 2003s Paris-Brest-Paris, but received disappointing news in November 2003. Since Nichols' initial test two years earlier, Breedlove's hip bone density was down 3.7 percent, although his lower-spine density was up 1.5 percent.
"My radiologist told me he's seen couch potatoes with stronger bones," says Breedlove. "Of course, their cardio systems ain't worth stink. So pick your poison." He plans to increase his calcium intake to closer to 3,000 mg, to lift weights all year instead of only during the off-season and to swap runs for rides some days. But stop the big miles? Not a chance.
Make Your Bones - 9 Ways to a Strong Skeleton
While the debate about cycling-induced bone loss is just beginning, we've seen enough evidence that we'd tell our friends to follow these tips. You're at increased risk if you're Caucasian or Asian, have a parent with osteoporosis, trained to excess as a youth, or took steroids.
- USE SUPPLEMENTS to get at least 1.200 mg of calcium per day. It's probably most effective if taken in 2-4 doses throughout the day. Increase calcium intake by 200 mg for every training hour beyond one per day. Help your body absorb it by taking 400-800 IU of vitamin D per day, according to Oregon Health & Science University.
- ADD YOGURT, MILK (any type) and other high-calcium products to your regular diet and post-ride refueling. Each serving contains 200-230 mg of calcium.
- CUT BACK ON SMOKING, ALCOHOL AND SODA, all known bone thinners.
- LIFT WEIGHTS AT LEAST TWICE A WEEK, year-round. Some experts believe using heavy weights in three sets of 6-10 reps to failure (the point where you lose form) puts maximum stress on muscles and bones, which cues the bone-strengthening mechanism. But just about any weight-lifting program will improve bone density.
- DO BACK EXERCISES TWICE A WEEK to strengthen the lower vertebrae, which might become particularly weak in cycling due to lack of movement. Do back extensions or, at home, do yoga's cobra pose: Lie on your stomach with your hands behind your neck, or with your palms flat on the floor in front of you, shoulder-width apart, then raise your head and chest off the floor. Hold for 5-30 seconds, and repeat 3-10 times.
- RUN, HIKE, SKIP ROPE OR JUMP AROUND with your 6 kids for 20-30 minutes, two to three times a week, to promote bone growth with weight-bearing vibration. "The impact must be significant." says Christine Snow, director of OSU's Bone Research Lab. "The vibrations of cycling aren't enough." A Johns Hopkins study found that light-intensity activities such as walking did not strengthen bones. Other studies hint that as few as two minutes of significant impact or vibration per day bestow some benefit.
- STAND UP MORE OFTEN ON THE BIKE. It loads weight on your legs.
- MOUNTAIN BIKE MORE. Sally Warner's study found significantly higher bone densities in mountain bikers, particularly in the upper body, probably from the occasional hiking, jarring ride and high-torque climbing.
- GET A BONE SCAN. Know where you stand. Insurance companies typically won't pay for the 51,000 DXA bone-density scan until men are 65 and women are 50. Doctors we contacted suggest that you might be covered under most insurance policies if you appear to hunch when you see your doctor, complain of aches and mention that your spouse or friends say you look shorter, which could indicate premature kyphosis, a grandmotherly forward slump.-R.M. W.