Fountain of Youth - From the new
scientist....
THE five men in the publicity photo
are the image of American youth, circa 1966: well groomed, smiling,
confident. America was racing for the moon, but these young men were looking
beyond, doing their bit for astronauts in orbiting space stations and
perhaps eventually a trip to Mars.
They had volunteered for what is
now known as the Dallas Bed Rest and Training Study. The goals were twofold:
to simulate the effects of weightlessness on astronauts and to determine how
quickly the body recovered when normal life resumed. As an aside, the
scientists who were monitoring the effects of such slothfulness hoped to
find out why hospital patients feel as weak as kittens after lengthy stays
in bed. Speculation at the time focused on extended inactivity causing blood
to pool in the limbs, producing a dizzying drop in blood pressure when you
stood up. But maybe it was something more insidious, such as changes in the
heart or lungs. In 1966, nobody knew.
One of the volunteers was Gregg
Hill, a college student with an interest in exercise physiology. He was also
a runner who could do the mile in 4 minutes 45 seconds - admittedly not
Olympic standard but no slouch either.
Initially, the study leader,
Carleton Chapman of the University of Texas Southwestern Medical School, had
signed up six volunteers: three athletes and three less active students, to
see how they compared. But one of the athletes, "a big handsome hunk of
a swimmer", backed out, Hill says, when he discovered how many needles
would be stuck in his body.
The tests were in part inspired by
the findings of Archibald Hill, the British pioneer of biophysics. Forty
years earlier he had discovered that during exercise the body reaches a
state of maximal oxygen uptake which cannot be exceeded no matter how hard
you work. If you try to go faster, you fall into what athletes call
"oxygen debt", in which you can briefly sprint, but must then stop
to recover.
Maximal oxygen uptake is referred
to as VO2max. The standard test monitors
your oxygen consumption as you run on a treadmill, with a technician
gradually turning up the grade until you have to pack it in. For
competitively inclined people who try to "beat" the test, it's a
brief but brutal workout.
In addition to VO2max,
Chapman's team wanted to know everything possible about the students'
hearts, lungs and overall fitness. They took chest X-rays to determine the
volume of their hearts. They measured lung capacity by making them exhale
into a device called a spirometer. They weighed them underwater to calculate
how much body fat they were carrying.
The tests that frightened off the
swimmer were designed to measure the amount of blood pumped by each beat of
the heart (the "stroke volume") and the fraction of oxygen removed
from it by the leg muscles. Today, there are non-invasive ways to measure
these, but in 1966, one needle had to be stuck into a vein in the right arm
and another into an artery in the left one. Squirts of green dye were
injected into the vein, and the amount by which the dye was diluted when it
appeared in the artery revealed the volume of blood with which it had mixed
in the heart. Measuring how much oxygen the legs were using required yet
another needle to extract samples from a leg vein - all while running on a
treadmill. Definitely not a test for the squeamish.
Preliminaries completed, Hill and
his friends went to bed. Their diets were monitored so that they wouldn't
gain weight, but exercise was strictly forbidden. The only concession was a
single brief shower halfway through the experiment.
Bored, Hill and his wardmates read
a lot, watched TV and listened to music - although that sometimes caused
energy-consuming arguments. "I like classical," Hill says,
"but I tolerated pop for the sake of peace."
When they were finally released,
the men were placed on trolleys and wheeled to the sports lab for a repeat
of the initial tests. The results were stunning. Chapman's team found that a
mere three weeks of inactivity had cut VO2max
by 28 per cent and stroke volume by 25 per cent - more than 1 per cent per
day. Overall, their hearts had shrunk 11 per cent, and two of the
non-athletes fainted during their first efforts on the treadmill.
As word filtered out, hospital
doctors began prodding surgical patients out of bed as soon as possible and
cardiologists began prescribing exercise rather than bed rest for heart
patients. Hill's boring summer job had changed the face of medicine.
Back on his feet, however, Hill now
had to work harder, as the study entered its "training" phase. For
the next 55 days, he endured intense workouts, including time trials on the
track. "That was rough," he says. Early on, he even had trouble
driving because his legs were so sore from the training that they trembled
when he pushed the pedals. By the end, though, he and the other athletes had
fully recovered, and the three non-athletes were in better shape than at the
start of the study.
An academic paper, published in
1968, reports these findings in dozens of pages of charts and dry language.
Hill puts it more succinctly. "The heart is a tremendously flexible
organ," he says. "It remodels itself to meet changing conditions
very quickly - much more quickly than muscles respond to
weightlifting."
In later years, Hill maintained his
interest in exercise physiology but went on to become a college instructor
in computer science. Then, in 1996, he received a phone call. Was he willing
to be part of a follow-up study? This time there would be no needles and no
need for bed rest.
The follow-up was the brainchild of
Darren McGuire and Benjamin Levine from the University of Texas Southwestern
and Presbyterian Hospital in Dallas. Their interest wasn't in bed rest, but
in the effect of age on cardiovascular fitness.
Few had looked at this before and
those who had tended to focus on professional athletes, making it difficult
to separate the effects of ageing from those of retirement from sport.
Hill's group provided a unique opportunity because no such group of
relatively ordinary people had ever been so comprehensively studied for so
long.
A few months later, all five men
were back on the treadmill - this time minus the needles. Today,
sophisticated imaging techniques show how well the heart is functioning.
Then they were put on tough training routines.
“
In the space of three weeks their hearts had shrunk 11 per cent
”
The follow-up findings, published
in 2001, were nearly as spectacular as the original ones. First, McGuire and
Levine discovered that 30 years of ageing had taken less of a toll on Hill
and the others than 20 days of bed rest. Even though all five men had lost
condition (and gained weight), the decades had reduced their VO2max
only half as much as their stints in bed.
That was interesting, but more
important was what happened when the men were put on exercise programmes
building up to about 3 to 5 hours per week. Within six months, their VO2max
levels rebounded all the way to what they had been at the end of the 1966
study. "We reversed 30 years of ageing with six months of
training," Levine said.
This did not, however, give Hill
back his ability to run a 4:45 mile, most probably, he suspects, because his
ageing tendons have lost elasticity. Still, he likes the fact that doctors
and nurses often tell him he has the vital signs of a teenager. "There
is a fountain of youth," he says. "It's just that you have to work
hard to drink from it." Next year, he will find out how successfully
he's drunk from it since 1996, when he takes part in the 40th anniversary
follow-up. After that? Well, there are always the 50th and 60th
anniversaries.
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UNDERGROUND
Right!
A good example of a Beckenham Runner's breakfast. All the major food
groups are represented.
Wrong! Would Roger Bannister have run the four minute mile after one of
these? If you think he would have done, then you haven't tried one.