New NASA research suggests bones that are slightly
shaken may help astronauts stay healthier during long
spaceflights, and could be used to help people suffering
from bone loss here on Earth.

Scientists funded by NASA and its National Space Biomedical
Research Institute in Houston uncovered evidence that barely
perceptible vibrations may stimulate bone growth, which
would benefit astronauts on extended space missions, the
elderly here on the ground, and other people immobilized by
paralysis or bed rest.

A team of researchers, led by Dr. Clinton Rubin of the State
University of New York at Stony Brook, discovered that
normally active animals exposed to 10 minutes per day of
low-magnitude (.25 g), high frequency (90 Hz) vibrations
experienced increased bone formation when compared to the
control group.

In addition, when animals, prevented from regular, weight-
bearing activity, were exposed to 10 minutes of vibrations
per day, bone formation remained at near-normal levels.
However, animals not exposed to the treatment, but
participated in 10 minutes of weight-bearing activity each
day, still exhibited signs of significant bone loss.

While preliminary results are encouraging, “a full clinical
study must be completed to demonstrate the effectiveness of
using vibrations to recover bone mass and architecture in
people with osteoporosis or to prevent the bone loss known
to occur in astronauts during long duration space flight,”
Rubin said.

The technique works by stimulating the bones’ stress
response. “Bone and muscle are plastic tissues that undergo
structural changes to match the functional demands that are
placed on them,” said Dr. Bruce Hather, a muscle specialist
at NASA Headquarters’ Office of Biological and Physical
Research in Washington. “The people you see working out with
barbells at the local gym typically have larger muscles and
stronger bones than someone who does little or no exercise.”

While researchers do not fully understand the physiological
mechanism at work, the vibrations appear to fool the bones
into thinking they are working hard. This results in the
retention, and even additional growth, of bone tissue.

This research may be particularly useful for long-duration
space missions of the future. The absence of mechanical
stimulation to bones and muscles in microgravity leads to
substantial bone loss and muscle weakness in astronauts. In
flights lasting four to six months, astronauts can lose bone
mineral density approaching 1.6% per month.

Although there has not been enough long-term research to
determine if such rates of bone loss would continue,
scientists estimate that during a two and a half-year round-
trip mission to Mars, astronauts could lose up to half of
their bone density from specific parts of the skeleton. This
could seriously jeopardize an astronaut’s health on return
to Earth.

At the same time, current astronaut exercise regimes for
long-duration space missions are time consuming, eating away
at valuable crew time. Low-level vibrations may offer a
countermeasure for this condition without the need for a
medicinal intervention.

Other members of the research team include Gang Xu and
Stefan Judex, both of the State University of New York at
Stony Brook.