may shortchange bones
density increases from exercise involving more impact than cycling,
such as running or soccer.
Ricardo DeAratanha, Los Angeles Times
little high-impact exercise can help prevent osteoporosis, experts
Jeannine Stein, Los Angeles Times Staff Writer
October 22, 2007
is terrific exercise, hitting the cardiovascular system and major
muscle groups simultaneously -- but it may not be the best thing
for building strong bones. Compared with male runners, male cyclists
appear more likely to have lower-than-normal bone density.
would think that cyclists are very healthy because they spend
all those hours training," says Pam Hinton, associate professor
of nutritional sciences at the University of Missouri-Columbia
and coauthor of the study accepted for publication in the journal
Metabolism. "In other aspects they are -- cardiovascular
health and body composition. But in this one aspect, they're not
doing so well."
study tested the bone mineral density of 27 cyclists and 16 runners
ages 20 to 59 who had engaged in their sport a minimum of six
hours a week for at least two years. Hinton controlled for diet,
past exercise and weight training. Whole body scans and blood
tests showed that 63% of cyclists had osteopenia of the spine
or hip, compared with 19% of the runners.
is bone mineral density that's lower than normal but not so low
to be considered osteoporosis, or very low bone mineral density.
Not all who have osteopenia will develop osteoporosis, and treatment
isn't always required.
of those with osteopenia were in their 20s and 30s, "and
that was pretty alarming to me," Hinton says. "I thought
I'd just see it in guys who were older and had been riding for
general, men may not be as much at risk for low bone density as
women -- especially postmenopausal women. But Hinton believes
they should be concerned because osteopenia can lead to osteoporosis
and injuries such as hip fractures.
cells are surrounded by fluid that, when hit with an impact force,
moves back and forth. That action signals to the bone cells to
add more mass."You lose bone mass quickly if there isn't
some kind of mechanical loading on the bone," Hinton says.
she adds, best comes from movement involving impact -- running,
playing basketball or soccer, or doing plyometric exercises such
training can also exert force on the bone, says Hinton, but not
as much as during impact, perhaps accounting for the lower bone
mineral density in cyclists. Some of the study participants protested
that the muscle contractions that occur when pedaling and standing
on the pedals should account for some impact. "But the pedal
is moving with you," she says. "You don't have the earth
resisting your body."
recommends that cyclists add a little variety to their workouts
to help increase bone density: running, playing basketball, jumping
rope or doing plyometrics a couple of times a week.
you're young, you should be maximizing your bone density,"
she says, "and as you get older, exercise slows the rate
of loss. So it's really important no matter where you are in your
life to be doing some kind of bone-loading exercise."