297A87EF-619E-4D3A-8D1D-30F8F50DBFBF.jpg
A combination of factors are leading to new world records in track and field and other sports, experts say. (Credit: iStockphoto/Tomas Bercic)

Olympic Games: Researchers Explore What Makes Better Athletes, The Physiology Of Performance, And More

ScienceDaily, Aug. 6, 2008 — 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 complete 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.

BF142952-6D8B-4703-9454-272D7B4AC36D.jpg
China Photos/Getty Images

People unfurled a Chinese flag in Beijing

ScienceDaily— Functional magnetic resonance imaging of men and women under stress showed neuroscientists how their brains differed in response to stressful situations. In men, increased blood flow to the left orbitofrontal cortex suggested activation of the “fight or flight” response. In women, stress activated the limbic system, which is associated with emotional responses.

There are many books and movies that highlight the psychological differences between men and women — Men are From Mars, Women are From Venus, for example; but now, neurologists say they have brain images that prove male and female brains do work differently — at least under stress.

Same species, different genders … And now, a new high-tech scientific study reveals the differences between men and women may really start at the top. Researchers at the University of Pennsylvania used a high-tech imaging method to scan the brains of 16 men and 16 women. The subjects were placed inside a functional magnetic resonance imaging machine, or fMRI.

“Using this state-of-the art-functional magnetic resonance imaging technique, we try to directly visualize what the human brain does during stress,” Jiongjiong Wang, Ph.D., a research assistant professor of radiology and neurology at the University of Pennsylvania in Philadelphia, told Ivanhoe.

Researchers then purposely induced moderate performance stress by asking the men and women to count backward by 13, starting at 1,600. Researchers monitored the subject’s heart rate. They also measured the blood flow to the brain and checked for cortisol, a stress hormone.

When the scans were completed, neuroscientists consistently found differences between the men’s stressed-out brains and the women’s. Men responded with increased blood flow to the right prefrontal cortex, responsible for “fight or flight.” Women had increased blood flow to the limbic system, which is also associated with a more nurturing and friendly response.

Doctors say this information may someday lead to a screening process for mood disorders. “In the future, when physicians treat patients — especially depression, PTSD — they need to take this into account that really, gender matters,” Dr. Wang explains.

Other experts caution that hormones, genetics and environmental factors may influence these results, bringing to light yet another difference between men and women. Neuroscientists say the changes in the brain during stress response also lasted longer in women.

WHAT IS fMRI? Magnetic resonance imaging (MRI) uses radio waves and a strong magnetic field rather than X-rays to take clear and detailed pictures of internal organs and tissues. fMRI uses this technology to identify regions of the brain where blood vessels are expanding, chemical changes are taking place, or extra oxygen is being delivered.

These are indications that a particular part of the brain is processing information and giving commands to the body. As a patient performs a particular task, the metabolism will increase in the brain area responsible for that task, changing the signal in the MRI image. So by performing specific tasks that correspond to different functions, scientists can locate the part of the brain that governs that function.

FIGHT OR FLIGHT: Certain events act as “stressors,” triggering the nervous system to produce hormones to respond to the perceived danger. Specifically, the adrenal glands produce more adrenaline and cortisol, releasing them into the bloodstream. This speeds up heart and breathing rates, and increases blood pressure and metabolism. These and other physical changes help us to react quickly and effectively under pressure.

This is known as the “stress response,” or more commonly, as the “fight or flight response.” But if even low levels of stress go on too long, it can be detrimental to one’s health. The nervous system remains slightly activated and continues to pump out extra stress hormones over an extended period, leaving the person feeling depleted or overwhelmed, and weakening the body’s immune system.

STRESS-REDUCING TIPS: There are several easy, practical things people can do to reduce the amount of stress in their lives. (1) Be realistic and don’t try to be perfect, or expect others to be so. (2) Don’t over-schedule; cut out an activity or two when you start to feel overwhelmed. (3) Get a good night’s sleep. (4) Get regular exercise to manage stress — just not excessive or compulsive exercise — and follow a healthy diet. (5) Learn to relax by building time into your schedule for reading or a nice long bath.

ScienceDaily — Computer models of human locomotion are helping engineers understand why walk and run instead of hopping and skipping. The models are revealing that walking and running are the most energy-saving ways a person can move. The models could help improve rehabilitation therapies and the design of prosthetic and orthotic devices.

ORLANDO, Fla.–To get from one place to another, we walk or run without thinking much about why. But these two engineers did wonder why humans move the way we do.

They look funny doing their research, but Manoj Srinivasan and Andy Ruina aren’t comedians. They’re mechanical and aerospace engineers studying human locomotion, or how people get around.

“You can imagine a person being able to go from point A to point B in all kinds of crazy ways. But people mostly choose to walk,” Srinivasan, of Princeton University, tells DBIS. “The question is why?”

Srinivasan and his advisor, Ruina, designed a computer model to reveal the most energy-saving ways a person can move. Out of the thousands of possibilities, the computer chose walking and running, confirming a theory that’s been around for hundreds of years.

Srinivasan says, “Walking is the least energy consuming at slow speeds, and running is the least energy consuming at fast speeds.”

In a nutshell, we walk and run instead of skip because it takes less effort.

Andy Ruina, of Cornell University in Ithaca, N.Y., says, “So walking’s the gait that people use where there’s at least one foot on the ground, where your body moves approximately in a sequence of circular arcs.”

The researchers were surprised, however, when the computer also chose a third gait.

“And as far as we can tell, this thing looks — would look something like a tired run. Something like … like that,” Ruina says.

By studying the way we move, not only will researchers uncover more mysteries of the human body, but they hope to develop better prosthetic and orthotics devices.

Ruina and Srinivasan compared the three natural movements with what they call “many other strange and unpracticed gaits.” Their computer model simulated human traits

BACKGROUND: People’s legs are capable of a broad range of gait patterns, but we mostly use just two: walking and running. Cornell researchers have developed a computer model that could compare walking and running with an infinite variety of other gaits. It turns out that walking is the most energy-efficient gait for slow speeds and running is the most energy efficient gait for fast speeds. The new simulation also uncovered a “new”, seldom-used gait for intermediate speeds that looks like “tired” running with slow motion landings.

THE STUDY: The Cornell researchers compared the mechanics of walking and running with many other gaits (such as skipping), using a set of computer models that simulated physical measurements such as leg length, force, body velocity and trajectory, forward speed, and work. The aim was to discover the most efficient means for a person to get from one place to another with the least amount of muscle work. When people walk, they swing their body over a relatively straight leg with each step; when they run, they bounce up off a bent leg between aerial phases. Both these use less energy than more unusual gaits.

ABOUT BIOMECHANICS: Biomechanics is the study of the anatomical principles of movement, such as how birds and insects fly; how fish swim; and the most efficient ways a human can move. When we walk, with every step, the foot strikes the ground on the outside edge of the heel, the shinbone twists inward, and the foot rolls inward to bear the weight, absorbing the shock of impact. Then the shinbone twists outward and the foot begins to lift at the heel, providing a springboard for the toes to push the body’s weight forward off the ground. The foot then swings forward to repeat the cycle. Running has similar mechanics, but can be seen as a series of alternating hops from left to right leg.

August 19, 2008, Harvard University Medical School

Far too few of us are active and lean, the ideal combination for staving off heart disease and a variety of other chronic conditions. These days, most adults are overweight, inactive, or both. If you could be just one — active or lean — which would be better?

Researchers have been chasing the answer to that question for some time. Early research suggested that exercise could cancel out the health of carrying extra pounds. It’s a comforting idea, and one that has gotten a lot of press. But it is probably an oversimplification of a complex connection between weight, physical activity, and health.
Flip-flop findings

A team from the Cooper Institute for Aerobics Research in Dallas kicked the debate into high gear in 1998 with a provocative report. The researchers measured the body composition of 22,000 men and asked each to complete an exhaustive treadmill test. After eight years of follow-up, 428 of the men had died. Those who were overweight but deemed physically fit by their performance on the treadmill test were half as likely to have died as men who were lean but not fit. What’s more, death rates were virtually the same among fit overweight men and fit lean men.

Other Cooper Institute studies, some of which included women, further supported the idea that physical fitness is more important than weight, at least when it comes to living longer.

Not everyone agreed. North Carolina researchers looked at death rates among more than 5,000 men and women who took part in an early cholesterol-lowering trial. In this group, being fit offered little protection against the health risks linked to excess weight.

The latest salvo comes from the Women’s Health Study, a 10-year trial of aspirin and vitamin E among nearly 40,000 middle-aged women. As you might expect, the odds of having a heart attack, needing bypass surgery or angioplasty, or dying of heart disease grew with increasing weight and with decreasing activity. In each weight category (healthy, overweight, and obese), women who burned at least 1,000 calories a week with exercise or physical activity were less likely to have had heart trouble than those who were inactive. But here’s the kicker: exercise didn’t eliminate the cardiovascular hazards of excess weight.

Earlier work from the Women’s Health Study and the Harvard-based Nurses’ Health Study have also come to the conclusion that exercise doesn’t erase the health-related consequences of carrying too many pounds.
What does this mean for you?

Exercise is the single best thing you can do to prevent or control heart disease, diabetes, osteoporosis, gallstones, depression, and a host of other physical woes. That’s true whether your weight is squarely in the normal range or you could afford to lose a few pounds.

Consider exercise and a healthy weight to be partners in your efforts to stay healthy or get healthy. Physical activity and weight loss (when needed) improve the flexibility of arteries. They lower blood pressure and improve cholesterol levels. They ease inflammation throughout the body. And they make blood less likely to form clots inside arteries, which can trigger heart attacks and strokes. Exercise helps you lose or maintain weight, while losing weight can give you more energy and mobility for exercise.

This doesn’t mean you need to run marathons. Walking for at least 30 minutes a day is great. Walking for longer, or doing something more intense, is even better. You don’t need to instantly slim down to what’s considered to be a healthy weight, either. If you are overweight, losing just 5% to 10% of your weight will start you on the road to better health.

Tall people tend to be heavier than short people, so doctors use the body mass index (BMI), a measure of weight for height.

Overweight is defined as a BMI over 25; obesity is defined as a BMI over 30. A large waist — over 40 inches in a man or 35 inches in a woman — is worrisome, too.

Working out is a key ingredient for good health. So is aiming for, or keeping, a healthy weight. Put them together and you optimize your chances of having the healthiest and longest life possible.

For more information on fitness, order our Special Health Report, Exercise: A program you can live with, at www.health.harvard.edu/E.

Harvard University Medical School

Q: I read about the study suggesting that tight control of diabetes led to more deaths. My hemoglobin A1c level has been right around 7 to 7.5 for years. Should I back off? Or keep pushing for even lower glucose levels?

A. My take: keep pushing, and try to get under 7.0, but you and your doctor should use common sense as you do so.

Diabetes increases the risk for cardiovascular disease, including heart disease and stroke. Many people with the disease have conditions that add to the risk: excess weight, high blood pressure, high LDL cholesterol levels.

The study you’re referring to is called the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. It’s a large (over 10,000 people enrolled), government-sponsored randomized trial that was designed to test three possible ways for adults with type 2 diabetes to lower their risk for heart attacks and stroke: intensive lowering of blood pressure, lowering cholesterol levels with fibrates and statins, and very tight blood sugar control. It’s the tight blood sugar control part of the trial that was stopped in February 2008. The other parts of the trial are continuing.

Blood sugar levels go up and down with meals and other factors. Hemoglobin A1c levels are a good way of getting a handle on how they average out over several months. In the ACCORD trial, the target for the people in the tight control group was a hemoglobin A1c level under 6%, which is what you’ll see in people without diabetes. The people in the comparison group were supposed to aim for a level of 7% to 7.9%.

Like most large studies, the ACCORD study has a group of outside experts who regularly review the data to see if there are early indications of major benefit or harm. Either might be reason for ending a study prematurely. The ACCORD experts peeked at the data from the blood sugar–lowering part of the trial after an average of almost four years of treatment. In the sub-6% group, 257 people had died, compared with 203 in the comparison group, a difference of 54 deaths. That works out to about a 20% higher rate of death in the sub-6% group.

It takes a lot of dedication and frequent blood testing for people with diabetes to keep their hemoglobin A1c levels below 6%. But most researchers expected that it would be worth the trouble because it would lead to fewer heart attacks. And, in fact, the people in the tight control group did have fewer heart attacks relative to the more relaxed comparison group. But more of those heart attacks were fatal, which is why the death rate was higher with tight control. The researchers were surprised — and people with diabetes around the country, and perhaps the world, were, like you, left wondering about what they should do.

But here is why the American Diabetes Association and most experts I know continue to recommend that most diabetics shoot for keeping their hemoglobin A1c level at less than 7%. Other studies that have recently been published — or will be soon — have shown that targets of 6.5% are beneficial — or, at the very least, are no more dangerous than looser control. The findings from the ACCORD trial send a different message from virtually all other research. I think 6% may be pushing the tight blood sugar control just a little too far.

So, I would suggest you continue to rein in your blood sugar. Good, solid evidence shows that diabetics who keep their hemoglobin A1c levels under 7% are less likely to suffer the nerve and kidney damage that high blood sugar can cause.

It sounds like you are doing pretty well. You can get to the 7% mark with just a little more effort. But I wouldn’t go much lower than 7%, and would certainly try to stay above 6%, particularly if you have had any heart problems or other cardiovascular conditions.

By Nicholas Bakalar, August 12, 2008, The New York Times – Many people are sure that exercise improves their mood, and studies have suggested that exercise is almost as effective as antidepressants in relieving symptoms of depression. But a new study has found that even though people who exercise are less likely to be depressed or anxious, it is probably not because they exercise.

Dutch researchers studied 5,952 twins from the Netherlands Twins Registry, as well as 1,357 additional siblings and 1,249 parents, all 18 to 50 years old. They recorded survey data about the frequency and duration of exercise and used well-validated scales to uncover symptoms of depression and anxiety. The study was published Monday in The Archives of General Psychiatry.

Studying twins allowed the researchers to distinguish between genetic and environmental effects, and they found that the association of exercise with reduced anxious and depressive symptoms could be explained genetically: people disinclined to exercise also tend to be depressed. One does not cause the other.

This does not mean that exercise is useless in alleviating depressive symptoms. “Exercise may still be beneficial for patients being treated for an anxiety or depressive disorder,” said Marleen H. M. de Moor, the lead author of the study and a doctoral student in psychology at VU University Amsterdam. “But we couldn’t find evidence for a causal effect in the population at large.”