BORN to Run - Interview
Science World, Sept 4, 2000 by Nicole Dyer
Olympic champ Gail Devers is running for another gold medal–and she counts on science to win! Check out our Devers Q & A.
At age 33, Gall Devers is one of the world’s fastest women. At the 1992 Barcelona Olympic Games she grabbed her first gold medal in the 100-meter dash. Four years later at the Atlanta Olympic Games Devers captured two more gold medals–one for the 100-meter dash, another in the 100-meter relay (in which each of four team members sprints 100 meters and passes a baton). If she repeats history at the 2000 Olympic Games in Sydney, Australia, Devers will become the first sprinter in history to nab three Olympic gold medals in the 100-meter dash. How does the champion sprinter grab the gold? Read on.
Q What’s a typical Devers training day?
A “By 7 a.m., I’ve downed two bowls of oatmeal and am out the door,” Gall tells Science World. Devers hustles to the Parkway West High School track in St. Louis, Mo., where running coach Bob Kersee awaits her. She runs 100-meter sprints (nearly the length of a football field) for three hours, followed by a light meal–usually a turkey sandwich and vegetables, then sprints two more hours. Next stop: the weight room to pump iron for three straight hours. Does she ever slow down? “My friends tease me because I only know one speed–fast,” says Devers. “I run fast, talk fast, even sleep fast!”
Q What major hurdle threatened Devers’s track career?
A In 1990, Devers was diagnosed with Graves’ disease, a disorder of the thyroid g/and, a butterfly-shaped organ in the neck. The gland helps control the body’s metabolism, or rate at which cells release energy. Graves’ disease crippled Devers’s metabolism, causing her weight to plummet to 89 pounds and her hair to fall out in clumps. Doctors treated her with radiation therapy–energy waves that destroy abnormal cells; but the treatment also damaged her body’s disease-fighting immune system. As a result, a bacterial infection ravaged the runner’s feet, causing them to blister and bleed.
Q How did Devers get her health back on trackers?
A Determined to continue training, she ran in agony, layering on five pairs of socks to cushion painful foot sores. At one point, doctors thought they’d have to amputate her feet, but antibiotics, drugs that kill disease-causing bacteria, restored her health in the nick of time. “My track career was sidelined, but my Olympic dreams never died,” Devers says.
Q On average, you breathe 12 times per minute. After a race, Devers breathes 50 times per minute. Why?
A Normally, you breathe to give your body a steady flow of oxygen, a gas found in air. Breathing in oxygen is called aerobic respiration, and helps cells in your body convert the food you eat into a chemical called ATP (adenosine triphosphate). In turn, ATP provides energy to power your cells, which then fuels your body movements (see diagram, above).
TWO RUNNERS: TWO MUSCLE TYPES
Sprinter Gail Devers
Fast-Twitch Muscle Fibers
Gail Dever’s bulky muscles are designed to move fast! More than 80 percent of her muscles are made of long cells calledfast-twitch fibers. They contract (get smaller) and relax quickly–ideal for fast, powerful body movements over a short period, like sprinting.
Fast-twitch fibers don’t depend on oxygen for energy. Instead, cells get fuel from an oxygen-free reaction called anaerobic respiration.
Since fast-twitch fibers don’t use oxygen, they lack oxygen-filled blood vessels. As a result, they appear light in color.
Long Distance Runner Christine Clark
Slow-Twitch Muscle Fibers
Lean Christina Clark uses mostly slow-twitch fibers to run the marathon, a 42,164 meter (26.2-mile) race. Slow-twitch fibers are designed for slower movements over longer periods.
RELATED ARTICLE: GAlL FORCE: Running on Physics
What propels Gail Devers from start to finish? PHYSICS!
To start fast, Devers crouches down at the starting line, angling her body forward. This position helps reduce air friction (a rubbing force that opposes motion). When the gun sounds, she pushes back against starting blocks, which in turn “thrust” her forward with an equal and opposite force (Newton’s third law of motion).
As Devers accelerates (picks up speed) she leans forward. This keeps the forward forces (those ushing forward on her feet) in line with her center of gravity, center of her weight. If Devers kept her back straight she’d fall over backwards. Similarly, if Devers leaned over too far, she’d fall over forward.
Devers relies on kinetic energy (moving energy) in her leg muscles. The muscles work like springs that contract and stretch to create an upward force launching her over the hurdle.
Slow-twitch fibers are fueled by aerobic respiration, a chemical reaction that relies on oxygen. These fibers appear dark red due to oxygen-rich blood vessels.
Aerobic exercise, such as long-distance running, makes Clark’s muscles more efficient by using oxygen and glucose (sugar) as fuel.
However, during a 13-second, 100-meter race, there’s no time for a sprinter to breathe regularly. “Fortunately, Devers has enough energy stored in her cells to power her through a race without taking in a lot of oxygen,” says Robert Vaughan of the Tom Landry Sports Medicine and Research Center in Dallas, Tex. So how come after Devers crosses the finish line she pants and gasps for air? She needs to replenish her body with the oxygen it didn’t get during the race.
Q How does oxygen give you energy, anyway?
A After you inhale oxygen, your heart and lungs pump the gas into your bloodstream where it’s carried to your muscle cells. There, oxygen powers an exothermic reaction–a chemical process that releases heat and energy. This reaction breaks down glucose, a sugar that acts as the body’s main fuel source. The reaction produces carbon dioxide (gas you exhale), water, and ATP–used to power everything from moving muscles to cell division.
Q Why can’t Devers run a marathon like she races the 100-meter dash?
A As Devers tears down the track, eventually she can’t inhale enough oxygen to meet her body’s growing energy needs. That’s when her body automatically switches to a second type of breathing called anaerobic respiration–the body’s emergency system to produce fuel without oxygen. Like aerobic respiration, anaerobic respiration also breaks down glucose, but instead of carbon dioxide and water the reaction produces a chemical called pyruvic acid. Pyruvic acid provides a small thrust of energy to your muscle cells–just enough to power short bursts of activity. Then it breaks down into lactic acid, a chemical that builds up in your muscles and causes them to cramp, ache, and burn.
Q What’s the secret behind Devers’s muscle power?
A If If you want muscle power, you have to work at it. I practice between eight and nine hours a day, "Devers says. Practice sprints, for example, increase the number of blood vessels in Devers’s muscles so they store more oxygen. More oxygen spells more energy, which translates into faster running speed.
Q How does Devers stay so buff?
A Devers increases the size of her muscle cells through weightlifting, or exerting muscle force against a heavy object like a barbell. Weightlifting strengthens skeletal muscles–you have 640 of them–such as biceps and quadriceps. They are attached to your bones and control all voluntary movements, like walking, running, and bending. There’s no doubt Devers has mastered her muscles. Want to do the same? Start by working out 15 to 20 minutes a day.
Check out this web site for more Olympic coverage: www/NBCOlympicgames.com/kids
RELATED ARTICLE: Breathing Lessons
Oxygen helps your body turn food into energy. So more air in your lungs means more energy. How much air can your lungs hold? Try this experiment to find out.
Large plastic container (at least 4 liters) with narrow spout and lid (for example, an empty milk container) * sink or large pan * rubber tubing (at least 1 meter long) * 1 liter (1,000 ml) beaker or container * crayon * lab partner * metric ruler
Fill the sink with 5 cm (2 in.) of water. Then completely fill the container with water and cover with a lid.
Turn the container upside down and place it in the sink with the opening completely underwater. Remove the lid.
3, Slide one end of the tubing into the container’s opening.
Take a deep breath and blow into the other end of the tubing (have your partner hold the container upright). Blow out as much air as possible.
Mark the water level on the bottle with a crayon.
Empty the container, turn it right side up, and then use the beaker to refill it with water up to the mark.
7, Record the volume of water used to fill the container up to the mark.
8, Change roles and repeat the experiment.
The volume of water in the container represents the volume of air exhaled from your lungs. Compare your mark with your partner’s. Are the marks different? Why?
History: Have students research the history of track and field events at the Olympic Games. Make a list of the events, and include one or two historical facts about each one.
Did You Know?
Nintey-five percent of all energy used by cells in your body is produced by mitochondria.
The average person breathes in and out up to 3,453 gallons (13,071 liters) of air per day. That’s enough to fill almost 37,000 soda cans.
The Olympic marathon made its debut in 1896 in the Athens Olympic Games, but it wasn’t until 1984 that the women’s marathon became an Olympic sport.
The through gland controls the body’s metabolism, which regulates the rate at which cells release energy.
Aerobic respiration is a chemical reaction that uses oxygen to help cells produce energy. 3. Anaerobic respiration is a chemical reaction that helps cells produce energy without oxygen. 4. Unlike fast-twitch muscle fibers, slow-twitch muscle fibers depend on oxygen for energy. 5. To reduce friction at the start of a race, Gail Devers crouches down at the starting line.
Born To Run
Directions: After reading “Born To Run,” answer the following questions in complete sentences.
What does your metabolism do? And which organ controls it?
What is aerobic respiration?
What is anaerobic respiration?
What’s the difference between fast-twitch and slow-twitch muscle fibers?
How does Gail Devers reduce friction at the start of a race?
Sprinters use what type of muscle fiber?
Which type of muscle fiber do long-distance runners use?
Which runner depends mostly on oxygen for energy?
Why do sprinters have bulky muscles?
Fast-twitch fibers are ideal for what type of muscle movement?
How does Clark make her muscles work more efficiently?
Why do fast-twitch muscle fibers appear white?
Why do slow-twitch muscle fibers appear red?
Bonus: How many skeletal muscles do you have in your body?
National Science Education Standards
Grades 5-8: properties and changes of properties in matter * motions and forces * structure and function in living systems
Grades 9-12: the cell * motions and forces * matter, energy, and organization in living systems
For more on the science of sports:
To learn more about Gail Devers: www.gaildevers.com/
For the latest coverage of the 2000 Olympic Games in Sydney, Australia: www.nbcolympics.com/
Look at Your Body Muscles by Steve Parker, Copper Beech Books, 1997.
CHART READING SKILLS, p. TE5
- Sprinters use fast-twitch muscle fibers. 2. Longdistance runners use slow-twitch muscle fibers. 1. Marathoner Christina Clark depends mostly on oxygen for energy. 4. Bulky muscles help sprinters run faster over a short period of time. 5. Fast-twitch fibers are ideal for quick, powerful muscle movements. 6. Aerobic exercise, such as long-distance running, makes Clark’s muscles work more efficiently. 7. Fast-twitch muscle fibers appear white because they lack blood vessels. 8. Blood vessels make slow-twitch fibers appear red. Bonus: You have 640 skeletal muscles.
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