The 'best' medicine

By Alex Piazza
apiazza@umich.edu

Doctors call it one of the best prescriptions on the market.

It can help you live a longer life. It can keep you out of the hospital. It can improve your mood. And it’s free.

Yet more than 50 percent of adults do not get enough exercise, according to the Centers for Disease Control and Prevention.

Researchers at the University of Michigan make a good case for millions of Americans to realign their priorities and embrace exercise. Whether it’s testing the correlation between handgrip strength and longevity or studying the impact of physical activity on preschoolers’ attention span, U-M research emphasizes the importance of exercise on your overall health and wellbeing.

“The big thing about exercise research is that it’s so broad and it doesn’t have to just focus on one small area,” said Joe Hornyak, professor of physical medicine and rehabilitation at U-M. “It can involve everything from cardiac research to psychiatric research. And the unique thing here at U-M is that, regardless of what people are interested in, someone somewhere on campus is studying it. Exercise is no different, and it’s such an important topic to study because it’s fundamental in so many aspects of our life.”

Go the distance

Run longer. Be healthier.

It’s a pretty obvious connection—those who exercise more often are less susceptible to disease.

But how exactly does a man’s aerobic capacity affect his chances of suffering a spontaneous heart attack? And how does a woman’s running ability impact her brain function?

The answers could stem from a laboratory housed in the basement of U-M’s Biomedical Science Research Building.

There, Steve Britton and Lauren Koch have developed a unique rat model that provides scientists worldwide with a significant resource to study how exercise endurance capacity correlates with disease risks.

Twenty years ago, the U-M researchers developed a selective breeding process to generate rats that were either low-capacity runners or high-capacity runners.

“I am not aware of any other models that have been developed by direct artificial selection for aerobic capacity,” said Britton, professor of anesthesiology.

They measure the rats’ endurance on treadmills, and those that can run for longer periods of time breed together.

“We don’t train them to run,” said Koch, associate professor of anesthesiology. “This is just what they do. And in terms of our rat population, our lows are low and our highs are high. There are no real middle runners anymore. ”

The scientists have bred 36 generations of rats, with the high-capacity runners peaking at 78 minutes on the treadmill. The low-capacity runners exhaust at 15 minutes.

“We want to understand disease, we want to understand health and we want to understand physical performance,” Britton said. “These rats allow us to do that. Not everything is going to be equivalent to what you find in a human, but they’re both mammals and they both have similar genomes, so the things we can do in rats are much more extensive than what can be done in humans.”

Britton and Koch have worked with more than 400 scholars at 60 institutions worldwide on research involving the U-M rat model.

Researchers at Colorado State University are studying how exercise capacity can impact your chances of being diagnosed with cancer. Duke University researchers are testing how exercise endurance relates to brain function. And U-M researchers, like Koch, are utilizing the rat model to study the importance of exercise endurance in relation to longevity and aging.

Their initial theory that aerobic capacity plays a critical role in health and longevity seems to have panned out. The rats with elevated aerobic endurance are shown to be more resistant to obesity, fatty liver disease, sleep disorders and memory loss. And the average life expectancy of the high-capacity runners is between 28 and 45 percent higher than those rats with low aerobic endurance.

“There’s one main goal here: that is to get information that can lead to translation to help patients,” Britton said.

How low can you go?

“Build a six-pack in six weeks.”

“Lose 20 pounds in two months.”

The headlines are everywhere, from magazine covers to late-night infomercials.

Sure, they sound appealing, but it takes time and plenty of hard work to shed fat and pack on muscle.

And when the results don’t happen overnight, many people lack the motivation to stick with their exercise regimen.

But research from Jeff Horowitz suggests that each exercise session can make a difference in your overall health. This means you can improve your health even after the very first session of your new exercise program—and your workout doesn’t even have to be hard.

“People often get confused that they have to train for months or even years to reap the benefits of exercise, but that’s a complete fallacy,” said Horowitz, professor of movement science at U-M. “The reality is that you reap the most health benefits from your most recent exercise session. That’s why you shouldn’t get disgruntled and abandon your workout regimen. Exercise today and you’ll be healthier tomorrow.”

Horowitz tested 11 obese adults to determine how physical activity impacted their insulin resistance, which can lead to a variety of major health concerns like diabetes, heart disease, obesity and cancer.

Participants completed two separate workouts.

• A one-hour cardio session in which the adults burned 350 calories and maintained an average heart rate of about 100 beats per minute (BPM).
• A more-intense 45-minute cardio session in which the adults again burned 350 calories, but maintained an average heart rate of about 130 BPM.

The day after each workout, the participants’ insulin resistance had significantly improved.

“The exercise doesn’t have to be hard and it doesn’t have to induce pain,” Horowitz said. “You can get meaningful health benefits from just modest intensity exercise, as long as it’s between 45 minutes and an hour.”

Get a grip

How much do you bench?

This popular question is posed to men and women in gyms worldwide.

Perhaps it’s an ego thing, but many people consider the chest exercise to be the most accurate measure of a person’s overall strength.

But a recent study from two University of Michigan researchers shows that handgrip strength could be a very accurate predictor of overall strength.

“As arbitrary as it might seem, grip strength is a very solid proxy indicator for overall body strength,” said Mark Peterson, an assistant professor of physical medicine and rehabilitation, and faculty in the neuroscience graduate program at U-M.

Peterson and U-M colleague Chandramouli Krishnan examined grip-strength data from more than 7,100 Americans ages 6 to 80, then created population growth charts and curves across the age continuum. Here’s what they found:

• Strength peaks between 25 and 35
• Men lose strength at a greater rate than women
• 50-year-old men are a bit weaker than they were at age 20
• Normalized grip strength (strength relative to body mass) is a better indicator of health and function

But why should you worry so much about strength? Turns out that muscle strength has a pretty strong correlation to health and even longevity.

“Low grip strength, believe it or not, has been shown to be very robustly associated with metabolic risk, functional disability and even early all-cause mortality,” Peterson said. “Time and time again, research has shown that people who are strong, especially relative to their body mass, have very healthy metabolic profiles, meaning they’re at a lower risk for heart disease and diabetes.”

This latest work adds support to the body of work coming out of Peterson’s lab pertaining to the role of physical activity and muscle strength for preservation of health across populations.

Pay attention

A teacher asks her preschoolers to gather around for story time.

However, after just a few pages, a couple students drift off to sleep.

Others leave the group to play with toys in the corner.

It’s a common struggle among teachers to maintain their students’ attention, especially in a preschool setting.

Leah Robinson is well aware of preschoolers’ cognitive abilities, as well as the importance of movement and physical activity in young children.

The benefits of exercise on cognitive ability in adults and adolescents are widely known, but Robinson’s research is unique in that it shows physical activity also can improve attention in preschoolers.

“To my knowledge, our work is the first to report the effects of acute exercise on preschoolers’ cognitive function,” said Robinson, an associate professor of movement science in U-M’s School of Kinesiology.

Robinson travels with her students, including Kara Palmer, to underserved preschools with limited resources to support physical activity and motor skill development.

In one particular study, Robinson and her colleagues exposed 16 preschoolers to 20 minutes of physical activity. On a separate day, the children were exposed to 20 minutes of sedentary activity, like listening to stories.

Immediately after each session, the preschoolers’ attention was tested using a 13-page booklet in which they had to pick out a particular image.

 “We found the children were able to concentrate significantly more after the exercise session, as compared to after the sedentary session,” Robinson said. “If our research continues to produce similar results, this could transform educational policy development by confirming the importance of providing movement and physical activity opportunities throughout the school day for children of all ages.”