Fitness Article
of the Month
January 1998
Happy and
Healthy New Year!! I found this article on a site called the Why
Files. A great web site with a lot of little known and interesting
health info. The article below deals with athletes losing calcium
through sweating. An important study considering the fact that if
you don't replace the calcium, bone density seems to suffer. Low
fat and nonfat dairy products such as milk, yogurt, cheese, and
cottage cheese are some of the calcium rich foods I usually recommend.
Credit goes to Robert Klesges, spearheading the study and The Why
Files.
Best of Health,
Ron
The Scent
Of An Athlete
Robert Klesges,
a preventive medicine specialist at University of Memphis, says
his research into the relationship between sweat and bone thinning
began innocently enough: "We found something unexpected and
followed our noses."
Curious phrasing. Turns out that Klesges was on the trail of stress
fractures -- a painful condition associated with loss of bone mineral
density -- in top athletes. Although bone thinning usually occurs
during old age, in the disabling condition osteoporosis, it also
affects young people who get a phenomenal amount of exercise. Far
from being protected by extreme physical activity, these athletes
can actually lose bone mineral density. And since loss of bone mineral
-- mainly calcium -- correlates with loss of bone strength, thinning
can cause stress fractures and has been associated with shin splints.
Klesges singled
out a university basketball team for study and ruled out the possibility
that disease was causing the bone loss. Klesges, director of the
University of Memphis Prevention Center, knew the players were losing
six or more pounds of sweat during a three-hour workout, and wondered
how much calcium was being lost in that sweat.
While football players have a reputation for strenuous practices,
they actually "stand around and scratch a lot," jokes
Klesges. In contrast, drills for university basketball teams comprise
wind sprints, running, practice games and more running.
Since nobody
had ever collected athletic sweat for analysis, Klesges had to start
by inventing a collection contraption. He says his first effort
bore a resemblance to a sanitary napkin and was immediately nixed.
The players did, however, consent to wear a cotton tee-shirt for
the first hour of practice.
It wrings
true
Then came the
fun part. As Klesges and colleagues described it in the medical
journal JAMA ("Changes in Bone Mineral Content...", 17
July 1996, p. 226-30), "The shirt was then removed by a research
assistant (The Why Files bet it was a lucky grad student, but Klesges
insists he did it too) wearing rubber gloves and placed in a sterile
plastic container." The sweat was extracted and its calcium
content measured in a mass spectrometer.
Knowing the
percentage of calcium in the samples and how much sweat the players
lost during practice, Klesges calculated that they were losing an
average of 422 milligrams of calcium during three days' training.
Measurements of bone density showed that the average player lost
3.8 percent of bone mineral density during the three months between
preseason and midseason.
Klesges says
this is a significant amount, which explains the stress fractures
seen in the team and may even predispose the athletes to osteoporosis
later in life.
Complicated
calculus of calcium
Having documented
that loss, the researchers tried to reverse it by asking the athletes
to consume a calcium-rich sports drink and other calcium supplements.
The treatment worked: during the start of the second season, the
athletes actually gained an average of 2 percent in bone mineral
densities.
Klesges says
the research is one more demonstration that while exercise alone
cannot help bones stay dense and strong, moving your bones can be
good for them -- if you get enough calcium. He adds that a recent
reanalysis of dozens of studies showed that "exercise was related
to increased bone mass only if calcium intake was sufficient."
Are you getting
enough calcium? The U.S. recommended daily allowance has just been
raised; depending on your age and gender, it can range from 1,000
to 1,300 milligrams, according to the U.S.
Institute of Medicine.
This fitness
article is for educational purposes only. It is not medical advice
and is not intended to replace the advice or attention of health-care
professionals. Consult your physician before beginning or making
changes in your diet, supplements or exercise program, for diagnosis
and treatment of illness and injuries, and for advice regarding
medications. Thanks. RM
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