Medical professor teams with cycling legend Greg LeMond to spotlight ‘The Science of Fitness’

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If you ask biologist and local doctor Mark Hom, M.D., the upcoming Richmond 2015 UCI Road World Championships will be a display of mitochondrial power.

Beneath the pageantry, team tactics and worldwide attention, it will all boil down to who has the best energy metabolism. The co-author of Hom’s new fitness book, “The Science of Fitness: Power, Performance, and Endurance,” is legendary cyclist Greg LeMond, a three-time road world champion (once as a junior and twice as a professional). LeMond’s VO2 max, a measurement of how much oxygen an athlete’s mitochondria consume, was one of the highest ever recorded. “The Science of Fitness” explains fitness and health from a biological perspective, revealing the source of athletic inner power. Mitochondria, the dynamos of the cells, have their own DNA and are inherited maternally. Although LeMond is blond-haired and blue-eyed, his mother’s mother was Cherokee, meaning his mitochondria are from a hardy lineage of people who traveled halfway around the world on foot.

Another example mentioned in the book is Taylor Phinney, a contender in the road race and time trial for the U.S. men’s elite squad. Taylor is often associated with his father Davis Phinney, the former team 7-Eleven cycling pro, but Taylor inherited his mitochondria from his mother Connie Carpenter-Phinney, who was an Olympian and multiple cycling world champion in her own right. Although the men’s events will garner more media coverage, Hom thinks the women’s races will be even more fascinating from a biologic/genetic perspective.

Mark Hom, M.D., local Richmond physician and co-author of “The Science of Fitness: Power, Performance, and Endurance.” Photo by Mary Hom.
Mark Hom, M.D., local Richmond physician and co-author of “The Science of Fitness: Power, Performance, and Endurance.” Photo by Mary Hom.

As he approached his 50th birthday, Hom, who is a Virginia Commonwealth University School of Medicine alumnus, had made a pact with his wife that they would try to stay in great shape as they got older. They both took up cycling. After struggling to pedal only a few miles when they first began, they now log thousands of miles on their bikes each year. Hom’s interest in physical fitness, and in cycling specifically, led him to write “The Science of Fitness,” which focuses on the crucial role mitochondria play in exercise, disease prevention and nutrition.

In a recent article in the Richmond Times-Dispatch, Hom, a local Richmond doctor and assistant professor of radiology affiliated with the VCU School of Medicine, described how mitochondria — the power plants of our cells — convert food and body fat into the energy we need to exercise. Mitochondria multiply in response to intense exercise and diminish from lack of activity. Because their role in fitness and health is so central, it is important to take care of your mitochondria to ensure top physical performance and to prevent the diseases of the modern age such as Type 2 diabetes, obesity and metabolic syndrome.

“My analogy is that since mitochondria are inside your body and inside your cells, it is up to you to be a good shepherd to your mitochondrial flock by feeding them, making them strong and protecting them,” Hom said. That means maintaining a nutritious diet and exercising with intensity, while avoiding toxins that might weaken them.

When he began writing “The Science of Fitness,” Hom started thinking about examples to demonstrate the importance of mitochondria’s role in fitness. As a cyclist, his thoughts quickly turned to one of the sport’s legends: Greg LeMond. The three-time road world champion and three-time Tour de France winner obviously had superior mitochondria to power those wins but also suffered a near-fatal hunting accident in 1987 that knocked him out of cycling at the peak of his career.

After he recovered from his wounds, LeMond rebuilt his fitness to win again, but later suffered from muscle weakness and a lack of endurance. A muscle biopsy revealed the hallmark ragged red fibers of mitochondrial myopathy.

Greg LeMond, three-time Tour de France champion and three-time world cycling champion, designing a new bicycle frame in Minnesota (2015). Photo by Kathy LeMond.
Greg LeMond, three-time Tour de France champion and three-time world cycling champion, designing a new bicycle frame in Minnesota (2015). Photo by Kathy LeMond.

Hom, familiar with LeMond’s story, says this diagnosis was a seminal event in mitochondrial disease awareness. The lead shotgun pellets from the accident leaked toxins into LeMond’s body, damaging his mitochondria and prolonging his recovery time. LeMond was forced to retire from bike racing in 1994 when he still should have been in his prime years.

Because LeMond’s story presents such a poignant example of the connection between mitochondria and fitness, Hom decided on a whim to send an early draft of his book to the famous cyclist.

To his surprise, LeMond responded with a long email and agreed to co-author the book. LeMond, who always sought coaches knowledgeable in physiology, says that physical training needs the kind of scientific approach described in this book, something that trendy fitness books tend to lack. Through the book, LeMond gained a deeper understanding of how mitochondria shaped the highs and lows of his cycling career.

Hom said LeMond was always savvy about his training in his days as an athlete and his curiosity about fitness made him a pioneer in his sport in areas such as VO2 max testing, aerodynamics and power metering. Ultimately, LeMond became “arguably the fittest American athlete of all time,” Hom said.

Greg LeMond being VO2 max tested in the early 1990s. Photo by Daniel Zeman.
Greg LeMond being VO2 max tested in the early 1990s. Photo by Daniel Zeman.

“While collaborating on this book, I was amazed by his depth of knowledge,” Hom said. “Part of that was his own professional investigation into what would make him a better athlete, but it also became a personal quest when he was diagnosed with a mitochondrial disease. LeMond has a truly scientific mind: curiosity tempered with skepticism.”

Hom hopes “The Science of Fitness” can be a guide for others looking to get in shape and understand the fundamental biology behind fitness. The book, he said, is “anti-fad and anti-gimmick.”

“Our book is meant to help anyone at any age or fitness level to be as energetic and healthy as possible,” he said. “We have different chapters on exercise, nutrition, maintaining muscle mass, slowing the aging process and staying mentally sharp. Getting older is difficult enough. You don’t want to get old and have diseases too, especially diseases that can be largely prevented with exercise. In middle age, you can incur serious health risks if you stop exercising. For younger readers, it explains why exercise should begin at an early age in this era of childhood obesity. In each of our prefaces we explain how exercise transformed our lives as children.”

For his part, Hom plans to continue tending his mitochondrial flock on long, intense bike rides with his wife – as well as watching all of the world championship events with great interest.

The Science of Fitness: Power, Performance, and Endurance” received an endorsement from the United Mitochondrial Disease Foundation, the largest consortium of mitochondrial experts in the world. This spring, Dr. Hom spoke before U.S. Congress on behalf of the to promote mitochondrial awareness and research. The book can be found online at and is available in Richmond at Barnes and Noble’s Libbie and Short Pump locations.


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