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HEAVY DUTY: Weir’s
workouts improved dramatically after he
used the RTX device. |
Robert Weir, head coach of men’s track
and field, gets ready for his strength-training regime by
loading hundreds of pounds of weights onto both ends of a
bar that rests in brackets at shoulder height. Weir moves
under the bar, hoists it across his shoulders and does squats.
With each repetition, his knees and hips fold until his thighs
are parallel to the ground, then straighten—rep after
rep with the equivalent of a baby elephant draped around
his shoulders.
Like any athlete, Weir is well acquainted with his normal
performance range. Like any athlete, Weir looks for an edge.
A few years ago, he was intrigued when he heard about a device—that
has been called at various times the RTX, Core Control or simply
The Glove—invented by a pair of Stanford biologists.
Using the device to lower his core body temperature between
sets, he was able to lift 495 pounds in four sets of squats
instead of his normal two. He usually does squats only on Mondays,
but he decided to try a second series a few days later. That
Friday, he was able to increase the weight to 545 pounds. “I
was surprised the sets felt so good,” he says, but adds
that the real test came the following Monday. Weir, 44, expected
to see significant performance degradation due to the extra
Friday workout. Not only did he not see the decay, he increased
weight with every set. The RTX—for rapid thermal exchange—cooling
device “is a very serious piece of equipment,” he
says. “At my age, you don’t expect to be setting
personal bests during workouts.” He trained with the
cooling equipment for the 2002 Commonwealth Games, and placed
third in the discus. His oldest competitor was 15 years
younger.
RTX promises to enhance human performance in applications
ranging from sports to medicine to the military. It is the
brainchild of biological sciences professor H. Craig Heller
and senior research scientist Dennis Grahn, who have spent
nearly two decades studying temperature regulation in mammals.
Their lab, once devoted to hibernating ground squirrels and
marmots, now attracts San Francisco 49er football players,
military representatives from the Defense Advanced Research
Projects Agency, multiple sclerosis patients and sweating Stanford
athletes.
 |
COLD SHOULDER: Grahn and Heller
got a chilly reception from some scientists when
they first published their findings in 1998.
|
The fourth floor of Gilbert Biological Sciences Building
holds many iterations of Heller and Grahn’s inventions
to heat and cool humans. One of the earliest contraptions
circulated warm water around an arm encased in a clothes-dryer
duct and sealed with neoprene. It was designed to warm patients
recovering from anesthesia.
The drugs that render patients unconscious also make
them hypothermic. That’s useful because chilled patients bleed
less during surgery; but as they start to wake their violent
shivering can tear fresh sutures, damage teeth and put extra
stress on heart and lungs. It’s important to warm patients
quickly after a procedure, and traditionally that’s been
done with hot air or blankets. The trouble, Heller explains,
is that because the body’s core is still cold, blood
flow is pulled away from the skin to preserve internal body
heat. Warm blankets heat the skin, but without a ready supply
of blood circulating near the skin surface, this warmth is
not transferred efficiently to the body’s interior.
Heller and Grahn found that heating only an arm with their
device served to warm patients more rapidly than would have
been expected via normal heat transfer through the percentage
of skin surface being heated. After modifying their design,
they realized that they could achieve the same rate of rewarming
by encasing just the hand.
Mammals have specialized blood vessels in their palms
and other hairless skin surfaces—ears, nose, cheeks and soles
of the feet—that are designed to dissipate heat. (These
radiator-like structures—venous plexuses and arteriovenous
anastomoses—were described as early as 1858 in Gray’s
Anatomy.) By redirecting blood away from the capillaries
and into these blood vessels, the body can shed heat quickly.
What Heller and Grahn were seeing was the return trip: when
externally applied heat shocked open the radiators in the
cold palms of anesthesia patients, warmed blood was returned
straight to the heart, and the body was reheated from the
inside out. Applying a mild vacuum to the hand intensified
this effect.
Their finding that heat loss is not uniform across the
body was slow to gain acceptance. In the Journal
of Applied Physiology, where their research was first published
in 1998, Heller and Grahn issued a frosty rejoinder to skeptics: “since
we present not just a claim but hard data, it is nice
to emphasize that when data do not fit a model it is time
to reexamine the model.”
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|
Nigel Holmes |
After hearing of their rewarming research, a postdoctoral
student in molecular biology and neuroscience approached
them to see if the same radiator mechanism could be
used to cool the body core. Louise Bitting, PhD ’94,
had read that the cooling of cells containing the cystic
fibrosis mutation had halted the disease process in those
cells. She wanted to study if cooling might work outside
a Petri dish. (Bitting died unexpectedly in 1999 at the
age of 49.)
A lab technician who was also a body builder, Vinh
Cao, volunteered to be the test subject. To generate metabolic
body heat, Heller and Grahn had him do sets of pull-ups
to exhaustion. He started with a set of 14 pull-ups and
soon dropped to eight per set. After 20 minutes, they applied
cooling and a vacuum to Cao’s hand. When they asked him to do more pull-ups,
they were amazed to see his performance jump back up to 14
pull-ups. To make sure the improvement wasn’t caused
by the rest period, they did a study without cooling.
Cao did 10 pull-ups.
They continued to study Cao for the next six weeks.
If they applied cooling between sets, Cao’s performance
held steady in set after set. Without cooling, it decayed. “It
was as if he had no fatigue,” Heller recalls. “We
saw incredible gains over the next six weeks. He tripled his
capacity to 620 pull-ups.” Preventing muscle exhaustion
allowed Cao to train harder, leading to rapid gains in muscle
strength. Heller and Grahn theorize that more blood, and thus,
oxygen, is available to the muscles when the body doesn’t
have to route extra blood to the radiators for cooling.
Excited by what they had learned, they arranged a presentation
in 2000 to Stanford athletics coaches. Heller remembers
the stony faces and crossed arms that greeted them. “It was
not a warm welcome. The four or five coaches who showed up
didn’t seem to think that a couple of biologists could
tell them anything about performance enhancement.” Only
Weir agreed to try it. Off campus, the 49ers and Raiders football
teams were the earliest adopters—later followed by the
University of Miami football team, the NBA’s Milwaukee
Bucks and the Manchester United soccer team.
 |
CAN'T
TAKE IT WITH YOU: The
next challenge is finding a way to
mass-produce an affordable, portable cooling unit.
|
When a battery-operated model of the RTX became available,
the Stanford football team started to use it. Head
athletic trainer Charlie Miller made an inadvertent
breakthrough when one his players came off the field
with leg cramps during the third quarter of a game
against Boston College early in the ’02-’03
season. “Since cramps tend to recur, a coach has
to decide between benching a key player or keeping
him on the field and risk another cramp recurring in
the middle of play,” Miller
explains. In addition to conventional treatments—massage,
electrolytes, fluids—Miller had him put his hand
into the RTX. To his surprise, the cramp disappeared
and the player was able to finish the game. “When
the IV fluids worked [to revitalize a player], it wasn’t
the minerals or the rehydrating,” he says, “it
was because we were invasively cooling the players
down. We had noticed that if the IVs were kept on ice,
they worked better. Now we know why.”
Miller says the RTX is a competitive advantage because
it allows a coach to keep his best players on the field. Because
the device is so new, there are no requirements yet for the
host team to provide one to the visiting team, as there are
for other amenities.
Ever seeking a competitive edge, athletes began paying
regular visits to the fourth floor of Gilbert, causing
one of the staff to remark that the hallways had gotten
smaller. A former NFL player told Grahn, “This replaces the Juice,” referring
to steroids. Weirdly, cooling does mimic steroids in the way
it allows an athlete to recover from intense exertion quickly,
allowing someone to do more work in a shorter period of
time. But cooling doesn’t result in shriveled gonads
or ’roid rage.
Critics might worry that cooling masks the body’s
signals to stop. In fact, lab data show that athletes who
train with cooling perform better in all kinds of conditions—even
competitions when cooling is un-available. Heller says
removing heat from the body is no different from giving
it a drink of water in response to thirst. Asked whether
training with cooling might lead to overuse injuries,
Weir shakes his head. “It doesn’t allow you
to do work you couldn’t
ordinarily do. It allows you to recover faster.”
Meanwhile, researchers continue to investigate therapeutic
uses for cooling. One exciting area of research involves
multiple sclerosis, a disease where even a 1/2-degree
Celsius rise in core body temperature can lead to rapid
and dramatic physical and cognitive decline. (MS sufferers
say the sudden enervation feels as though a switch
was flipped.) The disease destroys portions of the
fatty myelin sheath that insulates nerves; heat disrupts
the electric impulses traveling along the frayed nerves.
Retaining strength—key
to staying out of a wheelchair—is
a significant challenge for MS patients, for whom fatigue
can lead to a spiral of debility.
Jim Seaton, a management consultant who lives in Washington,
D.C., has MS. Once a top runner and avid hiker, he
has to be cautious about exertion. He pushed himself
too far once and had to crawl back to his car in the
parking lot; recovery to his baseline level of functioning
took two days. Seaton, after hearing a radio report
about cooling athletes, arranged to try the RTX to
see if it reduced the fatigue that resulted when his
body warmed up. Using the RTX, he can cool to his resting
state in 10 to 15 minutes—and then continue to
hike. The RTX isn’t exactly convenient: the $4,000
unit weighs 12 pounds and has to be reloaded with ice
every 2 1/2 hours. But owning one changed his life. “I’m
already planning trips to the museum [and] to Europe
that I would have thought thrice about before.”
At their boneyard of core-cooling machines in the Gilbert
building, Heller and Grahn describe the difficulty
in perfecting the design for a functional, portable
RTX. There’s the
coffeepot-shaped version. The $400,000 version by a name-brand
design firm that really never worked. The version constructed
in a size-10 boot that, once loaded with tubes and a cooling
surface, wouldn’t fit on even a size-5 foot. Grahn’s
latest homemade version features soft vinyl against the hand
instead of metal. One design challenge is obvious—how
to create a vacuum-bearing glove flexible enough so
that its wearers can use their hands, not just sit
cooling their palms.
Variable temperature control is another desirable feature.
When a hot body core issues a command to open the radiators
and dump heat, the palm can override that command and
order the radiators to shut down based on local conditions,
i.e., if the palm touches a cold surface. This was
borne out in February when Grahn flew to Alaska to
observe dog teams competing in the Iditarod. Temperatures
rose to 46 degrees in Anchorage—downright
tropical for the huskies. Grahn watched sled dogs through an
infrared camera—and saw snouts and ears lit up like headlamps,
indicating that the dogs were shedding excess body heat. But
the cameras showed no heat loss through the dogs’ feet.
Snow under their paws prevented those radiators from
opening. Heller and Grahn have found in the lab that
the temperature under which the radiators shut down
in humans is highly individual.
Heller and Grahn have received a series of patents
through Stanford’s Office of Technology Licensing,
which will share in any royalties. They are founders
and major stakeholders in AVAcore Technologies, a Michigan
firm charged with making the RTX commercially viable.
(The company moved from the Bay Area to Ann Arbor in
2003 to take advantage of engineers laid off from the
automotive industry.) “It’s
hard to build a compressor small enough to be useful
in portable situations,” says
Ronald Piasecki, chief executive officer of AVAcore. “Eventually
nanotech may play a role in accomplishing our engineering
goals.”
Piasecki has overseen improvements to the RTX manufacturing
process, reducing the cost and time to build each Core
Control machine. “Clearly, the athletic market is
the low-hanging fruit,” he says of the 100 units
sold so far. “But
this fall we’re starting a study of MS patients in
conjunction with the University of Michigan neurology
department.”
Heller remains confident that the technology can be
brought to wide markets. “There are many applications of both
heating and cooling,” he says. “Firefighters, soldiers
in full gear in the Iraq desert, stroke victims [where cooling
patients can prevent further damage], cancer patients [where
heating can increase effectiveness of chemotherapy drugs],
cystic fibrosis, heatstroke victims”—all are
potential beneficiaries of RTX. |
