Mayo Clinic on the Summer Olympic Games: Better Athletes, the Physiology of Performance,...

Mayo Clinic on the Summer Olympic Games: Better Athletes, the Physiology of
Performance, the Lactate Threshold, the Aging Athlete and Much More

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ROCHESTER, Minn.July 31 /PRNewswire-USNewswire/ -- The world-record pace for
the marathon continues to improve for both men and women. For men, the record
pace for the marathon is now about as fast as the record pace for the
10,000-meter run just after World War II. Today, champion athletes are running
more than four times farther at speeds of well under five minutes per mile.

How can this be? Are humans simply built better or is there something else
behind the mind-blowing speeds on the racetrack?

Michael Joyner, M.D., an anesthesiologist at Mayo Clinic whose research
interests extend to exercise science, says that a combination of factors are
leading to new world records in track and field and other sports. He
attributes the improved records, not necessarily to genetics, but to training
harder and longer, improved medical care and the fact that people from
throughout the world now participate.

In studying the world records of sporting events like the marathon, the mile
and 10,000- and 5,000-meter races throughout the last 125 years, Dr. Joyner
says there are key primary factors at play. Prior to World War I, athletes
didn't train every day. They trained three to four times per week out of
concern they would "overtrain" or become stale. By the 1920s, athletes were
training more often and by the 1950s, especially in Eastern Europe, athletes
were training daily for hours at a time.

By the 1960s, more people from other countries were involved in competition
than ever before. Up until then, most champion athletes came from European
countries, the U.S., Australia and Canada. Since then, however, athletes from
the developing world have been able to participate. Since the 1960s, some of
the most successful athletes have come from the East African countries of
Ethiopia and Kenya.

"So we've gone from maybe one-fifth or one-sixth of the world's population
participating to where we now have a huge pool of people in the Olympic
Games," Dr. Joyner says.

Does this mean we've reached a plateau in terms of speed?

"At some level we've reached a physiological plateau. In general, the
champions of today don't have dramatically better treadmill times as compared
to elite athletes of earlier generations. What I think we are seeing is a
small effect due to better racetracks, shoes and improved sports medicine.
And, people are participating longer, so you have more competitive depth which
leads to better races and races designed to set world records," Dr. Joyner
says.

The Physiology of Performance

In endurance sports such as running a marathon, there are three physiological
determinants of performance: maximal oxygen uptake (also called VO2 max),
lactate threshold and running economy (sometimes called running efficiency).

Maximal oxygen uptake is the maximum capacity for oxygen consumption by the
body during peak performance. It is also a measure of aerobic fitness.
Generally, the higher the VO2 max during peak performance, the better the
cardiac output - which means the heart is bigger.

In a treadmill test of two young men - one, an athlete, and the other, not -
the athletic male generally has a VO2 max value of between 70 and 85
milliliters (ml) of oxygen per kilogram per minute, as compared to 45 in the
sedentary male, Dr. Joyner says.

What fraction of your VO2 max you use over a period of time can depend on your
lactate threshold, which is considered a marker of maximum steady-state
performance for athletes in endurance events.

"The lactate threshold is highly related to how people perform in an event
like the 10,000-meter race, marathons or a bicycle time trial. The physiology
and biochemistry behind it is complex and controversial, but it's a good
marker of when the regulatory and physiological control systems of the body
are in balance," Dr. Joyner says.

Old Wives' Tales - The Lactate Threshold

Intense exercise causes lactic acid levels to build up faster than the body
can metabolize it. For athletes, this can be good because in the process of
generating lactic acid, energy for muscle is also being generated. However,
Dr. Joyner says, there are some misperceptions about lactate levels.
Specifically:

* Lactate is not synonymous with muscle hypoxia: "The first misperception is
that somehow people don't have enough oxygen when they are making lactic acid.
That certainly can be true because lactic acid can come from a lack of oxygen,
but under most circumstances the athletes have plenty of oxygen and there is
plenty of oxygen in the muscle."

* Lactate is gone from the muscle in the 15 to 30 minutes after exercise and
does not make you sore: "The second misnomer is that lactic acid hangs around
in your muscle for long periods of time. You may hear things like this
individual is sore or not performing as well today because they have a lot of
lactic acid in their muscle from yesterday's event. Well, you can have very
high levels of lactic acid in muscle, but it's gone 15 to 30 minutes after
exercise - so lactic acid doesn't hang around a long time."

* Breathing oxygen on the sidelines does not help enhance lactate levels:
"Breathing oxygen on the sidelines really doesn't help - there's no evidence
that it works."

Running Economy

How well your muscles use oxygen and how well they can metabolize glucose
without producing a lot of lactic acid in the skeletal muscle (which can
contribute to fatigue) are both important for performance, Dr. Joyner says.
However, how much speed you can generate at the lactate threshold is also
important. This is known as running efficiency or running economy. Runners
with good running economy, for example, can generate more speed per given
oxygen uptake. The legendary Olympic champion Frank Shorter had outstanding
running economy and this likely contributed to his success. Lance Armstrong
also showed marked improvements in his efficiency when he returned to bicycle
racing after beating cancer and that clearly helped him win the Tour de France
seven times.

Most world-class athletes have a high VO2 max or, as Dr. Joyner says, "They
all have big engines and high lactate thresholds because they've been training
hard for a long time. Their muscles have adapted to run very fast without
releasing a lot of lactic acid.

"In cycling for example, when Lance Armstrong came back from cancer, he became
much more efficient - he could generate more power per given oxygen update.
That is the same as a runner being able to generate more speed per given
power. When you look at this small pool of elite athletes of runners, cyclists
and rowers, all of them have a high VO2, all have a large engine and all of
them have skeletal muscles that are designed not to produce a lot of lactic
acid. So the question then becomes who is the most efficient," Dr. Joyner
says.

The Aging Athlete

At 41 years old, nine-time Olympic medalist Darra Torres will be one of the
oldest female Olympians at the 2008 Summer Olympic Games. It is not unheard of
for a professional athlete to compete into his or her 40s, but it's unusual.
Torres, a swimmer who specializes in sprints, depends more on muscle power and
technique, not necessarily aerobic capacity.

Torres is not the first to compete into her 40s. Carlos Lopes was in his late
30s when he won the Olympic marathon in 1984. Jack Foster of New Zealand was
in his 40s and he placed highly in the marathon in the 1972 and 1976 Olympic
Games.

How can some athletes continue to compete into their late 30s and early 40s?

"Your VO2 max typically starts to decline in your 30s, but a highly trained
athlete can delay that decline until they are in their later 30s or even early
40s. An average sedentary person loses about 10 percent per decade starting at
about age 30, but for someone who is able to continue to train very hard into
their 40s and 50s, they only lose about half that much - primarily due to the
fact they continue to train hard," Dr. Joyner says.

The older athlete is redefining what normal aging is and what's possible for
people who are middle age or older."

It's Cultural, Not Genetic

"Nobody becomes a great athlete without prolonged intense training," Dr.
Joyner says. "As scientists search for genes and the determinants of
performance, they keep drawing a blank. There have been no major gene
discoveries saying that this gene really confers championship status or the
potential for championship status of one person."

Sports are complex behaviors for biologists, he says. Many genes contribute to
performance, but it isn't likely that one individual would have the right
combination of all genes that would give you a natural competitive edge, he
says.

"It can be very deceptive to say that since the Kenyans, and perhaps
Ethiopians, are dominating distance running, it must be genetic. In fact there
have been periods of time when other cultures have dominated distance running.
Before World War II, the Finns dominated distance running. After World War II,
the Eastern Europeans dominated distance running. They were just as dominant
as the Kenyans are now," Dr. Joyner says.

Dr. Joyner points to cultural influences in sports. "I think what the Kenyans
and Ethiopians have shown is the value of altitude training. They are
physically active their entire lives, they live at high altitude, they run to
and from school, they play soccer after school - all at high altitude (6,000
to 8,000 feet). There are not a lot of economic opportunities, so there is a
tremendous incentive for people to run and train hard," he says.

"So what the Kenyans have added is altitude training, hard training and large
numbers of highly motivated people, but their physiological data is not
dramatically different from other people. I think you can make the same
argument for the Eastern Europeans after World War II. If you were a pretty
good athlete, the government offered you and your family incentives to train
in an otherwise bleak economic landscape," Dr. Joyner says.

Doping

"One of the sad things in last 30 to 40 years of sport has been the emergence
of the pharmacological arms race, or doping," Dr. Joyner says.

Creating reliable tests for these illegal compounds has been difficult.
Several recent studies show that testing in humans for both steroids and
erythropoietin (EPO), a hormone that induces red blood cell production, is
very difficult. In testing for EPO, for example, a study suggests the tests
are ineffective unless administered shortly after having taken EPO, because
EPO doesn't have a long life in the body. But EPO's effects can last for
months.

Another study suggests that it is very difficult to detect the use of some
steroids through urine tests in some ethnic groups.

"Researchers have started to test the tests and have raised questions about
the accuracy of the existing tests. They've shown that if you don't do the
test soon after people take the drug, it may be very difficult to detect
(especially if EPO is take in low doses)," Dr. Joyner says.

The Bottom Line: Keep Moving

"Remember, while it's fun to watch sports and while we will all be tempted to
sit in front of the TV to watch the Olympics. The really important thing is to
get out and move. One hundred and fifty minutes of physical activity a week is
really the most powerful medicine anybody can prescribe. No matter what your
level of fitness - even if it's just walking - try to be as physically active
as you possibly can because that's the way to be a healthy old person and get
more out of life," Dr. Joyner says.

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SOURCE Mayo Clinic

Amy Reyes of Mayo Clinic, +1-507-284-5005 (days), +1-507-284-2511 (evenings),
newsbureau@mayo.edu