Red Bulletin UK 5/21

VENTURE
Fitness
Before becoming the
leading expert on
astronaut health and
fitness at the German
Aerospace Center in Cologne
in 2009, Professor Jörn
Rittweger conducted research
into a seemingly unconnected
subject. “Bed-rest studies,”
says the scientist. “Subjects
lay in bed for 60 days or
longer and we’d test training,
nutrition and electrical
stimulation. It simulates a lot
of what happens to astronauts
in space, and ultimately it led
to me getting this job.”
Going into space is
extremely hazardous to health.
With no protective atmosphere
or magnetic field, exposure to
radiation is increased. “On the
ISS, [radiation is] 300 times
higher than on Earth. On the
Moon, it’s 600 times higher.”
But the biggest factor – one
that relates most closely to
the professor’s bed studies
– is gravity, or the lack of it.
“Gravity is perhaps the
strongest environmental
stimulus since the start of
our evolutionary journey.
Our bodies have developed
mechanisms to ensure our
brains receive enough blood
when we’re upright.”
In zero gravity, however, up
and down don’t exist. “Within
hours, astronauts discharge
about a litre of urine to get rid
of the blood they’re no longer
storing in their legs,” Rittweger
says. “Low gravity also knocks
the ear’s balance system off,
causing nausea. It takes days
for the body to suppress this
‘space adaptation syndrome’;
astronauts learn to keep their
head still and not turn quickly.”
As the head of the centre’s
muscle and bone metabolism
department, Rittweger’s
prime focus is clear. “Of the
almost 500 muscles in our
body, almost half support
standing, walking or running,
and muscles only grow and
develop strength when they
meet resistance,” he explains.
With the lack of gravity on the
ISS, astronauts aren’t pulled
to the ground; there’s no
HONE
Striving for a celestial body
How does an astronaut maintain an out-of-this-world physique? Here’s the rocket science…
resistance, and muscle
atrophy sets in.” The human
body, he says, renews around
one to two per cent of its
muscle mass per day, but in
space (or long periods of bed
rest) it’s shed rather than
gained. And the same happens
to your bones: “Leg bones
lose about one per cent of
their mass per month.”
The solution isn’t simply
sending astronauts into orbit
bulked up. “We channel
calcium through our kidneys.
If an astronaut increases bone
mass before a trip, they’ll lose
more [calcium], which can lead
to kidney stones. You don’t
want that to happen in space.”
There’s also the effect on
metabolism: astronauts have
higher rates of adult-onset
diabetes, meaning an increase
in their blood sugar. Blood-fat
levels increase, too, and there
is a danger of atherosclerosis
Above: Professor Jörn
Rittweger of the German
Aerospace Center; top:
European Space Agency
astronaut Samantha
Cristoforetti in training
“Nowadays,
astronauts return
to Earth in much
better shape”
[plaque build-up on artery
walls that can cause blood
clots, strokes or heart failure].”
These changes may not
cause immediate problems
while the astronaut is in
space, but they become a real
issue once back on Earth.
“There are doctors for that,”
says Rittweger, “but it would
make Mars missions tricky.
They could last up to two-anda-half
years, and medical care
is hard to come by on Mars.”
This is why Rittweger and
his team have created a
comprehensive workout that
can be done in space.
The right stuff
“It’s not easy to recreate the
important stimulus for our
three largest muscle groups
– the back extensors, glutes
and leg muscles – which
account for a third of our body
mass,” says Rittweger. This
THE RED BULLETIN 89