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Title: Running to Extremes
100-mile races test the limits of human
Author(s): Ellen F.
Citation: July 13, 1998 p
Copyright © 2003 U.S.News
& World Report, L.P. All rights reserved.
ATHLETES; RUNNING & JOGGING; RACING; CARDIOVASCULAR
SYSTEM; RESPIRATORY SYSTEM; SPORTS TRAINING; WOMEN; TRASON,
Word Count: 1845
Abstract: Profile of long-distance runner Ann
Trason, with an examination of the physiology of this style of
running. With graphic: Pushing the inner limits.
Article Text: Ann Trason runs farther, faster than
most people think is humanly possible. On June 27, the
37-year-old Kensington, Calif., athlete won her 10th
consecutive women's title in the Western States Endurance Run,
a brutal 100-mile trail race through the Sierra Nevada range.
She did it by running almost nonstop for 18 hours and 46
minutes. The race taxes the limits of human performance, from
the nutritional to the biomechanical to the psychological.
Exercise physiologists have just begun to analyze the physical
and emotional consequences of this still little-known sport,
in which runners compete over distances substantially farther
than a 26.2-mile marathon.
Theoretically, any reasonably fit person could run 100
miles, but he or she must train for it. After only three
months of strenuous training, with runs three to five days a
week that include one long session of 30 to 60 miles, the
human body learns to use fuel and oxygen very efficiently. A
well-trained endurance runner will have a resting heart rate
around 43 percent lower than that of a sedentary person and
body fat percentages 27 percent lower. Cardiac output, the
amount of blood pushed through the circulatory system, expands
by 75 percent, so that more oxygen is delivered. The amount of
oxygen absorbed by organs and tissues also increases 30 to 50
percent, thanks to a doubling in the number and volume of
mitochondria, energy generators in muscle cells. Trason says
she not only tries to train her cardiovascular system but
teaches her stomach to digest food on the run and toughens her
legs to withstand hours on the trail.
Indeed, muscle cells work better with training; the number
of capillaries multiplies, delivering more oxygen to the
muscle tissue, while the amount of metabolic enzymes, proteins
that break down carbohydrates and fats, increases 133 percent.
Still, even the fittest have a hard time running 100 miles.
"Unlike a marathon, where you can get away with less than
optimal nutrition, the margin of error in a 100-miler is
zero," says Lindsay Weight, a physiologist at the Sport
Science Institute of South Africa in Cape Town, a leading
center for research on endurance physiology. On average, an
athlete who finishes Western States in 24 hours burns 16,000
calories and sweats 4 1/2 gallons of fluid.
It's difficult to take in that much food and water, but
runners must try. Of these two essentials, the most critical
is water. "You basically have to drink from start to finish if
you want to avoid dehydration," Weight says. And it's not just
a matter of replacing water: In sweating, the body may lose up
to 3 grams of sodium an hour, resulting in imbalances of the
key electrolytes, sodium and potassium, that regulate cell
function. These imbalances, if extreme, can cause muscle
cramping, nausea, fatigue, and confusion. Trason avoids
dehydration by eating salty foods (pretzels are a great source
of sodium) and carrying water bottles in her hands so she'll
remember to drink every 15 minutes. In Western States and
other races, runners are weighed en route and stopped by
officials if they've lost more than 3 percent of their body
weight, which is a sign that they are dehydrated.
Out of gas. Staying fueled during an endurance event is
just as difficult. The body uses three sources of
fuel--carbohydrates, protein, and fat. At first, protein,
which is stored in muscle, supplies 10 percent of energy and
body fat supplies 15 percent. The remaining 75 percent comes
from carbohydrates stored as glycogen, a complex sugar formed
by stringing glucose molecules together in the muscles and the
liver. After six hours of continuous effort, the body has
consumed most of its glycogen stores, and body fat becomes the
primary energy source. But because fats are metabolized less
efficiently than carbohydrates, someone who doesn't eat while
running will literally run out of fuel.
"Carbo loading," a common runner's practice of eating a 70
percent carbohydrate diet for three to seven days before a
race, helps stave off carbohydrate depletion by doubling the
glycogen available to both muscles and liver. Eating during
the competition helps refuel--but it may cause diarrhea and
nausea, which occur when blood flow that would normally aid
digestion is diverted to other organs. Trason considers nausea
an inevitable part of racing. "The harder I work, the harder
it is for me to eat. I just try to get down whatever I can."
That includes syrupy athletic supplements like GU and
PowerGel, hard candies, and even Coca-Cola, which, thanks to
the caffeine, promotes fat metabolism. In races, aid stations
along the way provide salty, high-energy snacks such as soup
and baked potatoes.
Mastering the metabolic demands of endurance running is
just one of the sport's many obstacles. A distance runner also
breaks down muscle and tears up cartilage and ligaments. With
each step, leg muscles and tendons absorb impacts two to four
times a person's body weight and use that energy to generate
the force that propels the body forward. With time, the
mechanical stress disrupts muscle fibers, tearing them in many
places. In addition, a runner's body starts breaking down
muscle protein as blood glucose levels fall, using protein's
building blocks, amino acids, for fuel. This cannibalization
causes further damage. The trauma can be severe; biopsies of
runners' leg muscle tissue after marathons clearly show
necrosis, or cell death, and swelling. Muscle damage is rarely
permanent, but it can take up to three months to repair.
Runners describe the fatigue and soreness associated with this
long-term tissue damage as "dead legs."
Long-term exertion also may damage muscles' mitochondria, a
process that is frighteningly similar to the damage that
occurs with aging. In studying an injured 27-year-old
endurance athlete, physiologists Alan St. Clair Gibson and
Mark Lambert, both from Sport Science Institute of South
Africa, found that the athlete's mitochondria were so ravaged
that they resembled those of a 60- or 70-year-old. Oxygen free
radicals, highly reactive electrons that are a byproduct of
oxygen metabolism, are a likely culprit, since they attack
cell parts. According to Gibson, prolonged exercise may
artificially age muscle mitochondria to the point that they
stop working properly.
Sickening. Just as insidious is the toll endurance running
exacts on the immune system. In a 1987 study of 2,311 Los
Angeles runners, 42 percent of those training for a marathon
reported at least one upper respiratory infection in the two
weeks before the race. After the event, 13 percent got sick
within two weeks, while only 2 percent of the control group,
which trained but did not compete, developed infections. Just
how exercise suppresses the immune system remains a mystery,
but there are clues suggesting that cortisol, a stress
hormone, may be involved, since cortisol levels are 15 times
higher than normal in post-race endurance athletes. Cortisol
is known to suppress the activity of killer T cells and
neutrophils, which combat infection. Damage to white blood
cells by free radicals and severe nutrient depletion may also
be involved. Perhaps the immune system can't marshal itself to
protect the body from infectious agents given its starved
Weekend joggers, and even marathon hopefuls, need not worry
that they are inflicting serious damage on themselves.
According to Weight, damage doesn't accumulate until a person
has run more than six hours. "That's why top athletes don't
last forever," Weight says; an ultrarunner can expect to
remain competitive for eight to 10 years. Trason plans to have
surgery to remove scar tissue in her ankle, the product of
years of high mileage, after this season and is taking time
off to consider life beyond running, including whether she and
her husband will have children.
Why is Trason so good, beating most of the men, including
her husband (she was fourth overall in this year's
competition)? She does have a physiological advantage: She is
very light, weighing only 105 pounds at 5 feet, 4 inches. It
takes less energy to move a lighter body and puts less stress
on bones and tendons. But her greatest advantage may be
Western States competitors have to stay focused for the
length of the race, which can take up to 30 hours, with
elevation gains and losses totaling 41,000 feet and
temperatures ranging from below freezing to over 100 degrees.
This year was especially tough, thanks to melting snow from El
Nino. Trason ran for about 20 miles on ice and at one point
tumbled into a crevasse. It's also possible to get lost.
Trason's closest female competitor, Corrine Favre of France,
took a wrong turn at Mile 78 and was unable to make up the
time. "Paying attention for such a long time is difficult,"
says Jack Raglin, an associate professor of kinesiology at
Indiana University who specializes in sports psychology. "The
mental fatigue can be overwhelming." Trason agrees. "You get
jumpy when you get that tired, and it's nerve-wracking to run
in the dark." For both safety and company, many athletes run
with a pacer, a volunteer who helps keep them on track. Trason
makes sure her pacer is well briefed on professional sports
scores. "You get consumed by Western States and forget that
there's life beyond the race." Trason also keeps up a running
dialogue in her head to keep herself going. "After 50 miles
your body just hurts. You have to keep telling yourself that
your mind is stronger than your legs."
Pushing the inner limits The body of any runner, even that
of an accomplished athlete like Ann Trason, has to struggle to
cope with the intense stresses of a 100-mile "ultra" race.
Mind over matter. It's impossible to avoid fatigue and pain
in a 100-mile race, but it's possible to adapt. Trason
prepares by running 30 to 40 miles on consecutive days so that
she knows how to run when exhausted.
Priming the pump. During the race, an ultrarunner's heart
pumps 75 percent more blood than while at rest. Several long
training runs a week spur growth of new capillaries, which
expands the circulatory system's capacity to deliver its
Keeping the tanks filled. An ultrarunner's body burns 650
calories and loses 24 ounces of water an hour, so a runner
must refuel throughout the race. Aid stations offer
nutrient-rich foods as well as water and sports drinks to
Healing muscles and tendons. The stress of pounding along
the trail strains tendons and tears muscle fibers, and the
body also robs protein from muscles to burn for energy. A
post-race massage and a few weeks of leisure prompt immune
cells to slowly remove damaged cells and stimulate the growth
of new ones.
Sources: Lore of Running, Human