Biology & Medicine

The science of fitness – and what motivated us to learn about it

A cycling legend and a doctor share stories of struggle and inspiration — and how science illuminated a path to recovery

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Tour de France winner Greg LeMond and physician Mark Hom share a passion for cycling. Their paths would cross under unusual circumstances, leading them to co-author The Science of Fitness, just published by Elsevier.

In the excerpts that follow, LeMond shares his personal triumphs and struggles with cycling, fitness and health so others might benefit from his experiences. Dr. Hom then describes how cycling helped him transform from "a scrawny kid" to one who was strong and fit. He explains the science behind fitness and athleticism, including his discovery about the crucial role of mitochondria and how they affect our health and performance.

These excerpts are from the preface, which can be downloaded in full at the end.

Greg LeMond riding in the 1991 Tour de France

Greg LeMond: "At 25, I was on top of the world; nine months later, I was clinging to life"

I knew I was dying. Blood poured from my wounds, spurting wildly from my neck. I was trying to cry out, but with every breath I choked and gargled through the blood in my throat. Inside, I repeated over and over: Oh, my God, I'm shot! My strength seeped away into the scrub and brush of the remote northern California ranch.

The shotgun blast was unbelievably loud, right in my ear. My brother-in-law accidentally fired just as I stepped out from the cover of a huge wild raspberry bush in front of him; then all I knew was noise and confusion. I thought my own gun had gone off, and I stared at it, utterly confounded. Our small family hunting party was 40 miles from the nearest hospital, and I was bleeding to death. Oddly, I was not feeling any pain, but I wanted so badly to tell the others to get me an ambulance; I needed help, I was dying here.

It seemed hours until the California Highway Patrol helicopter arrived, although I learned it was more like 20 minutes. Paramedics secured me to the outside of the two-man helicopter. I watched the rotor blades cutting across the clear April sky. What a strange, strange way to go, gazing into the heavens.

We landed with a thump at the University of California Davis Medical Center in Sacramento. The last thing I remember was the emergency room physician slicing into me and inserting a chest tube. Pain had made itself known. I was not conscious again until some six hours later, after a team of diligent surgeons saved my life.

The Science of Fitness

The Science of Fitness coverIn The Science of Fitness: Power, Performance, and Endurance, just published by Elsevier, authors Greg LeMond and Dr. Mark Hom explain the connection between exercise, nutrition and physiology in layman's terms for experienced and amateur athletes as well as trainers and those interested in developing a serious exercise and fitness regimen. Athletes seeking optimal results are often enticed by the promises of the latest health, diet and fitness strategies, forgetting that science actually holds the keys to their success. This book includes medical and fitness advice about exercise and nutrition for enhanced athletic performance, higher quality of life, disease prevention and slowing of the aging process.

Dr. Hom writes:

As a radiologist, I can see deep inside the human body using state of the art medical imaging ... I can see beyond the skin surface and see my patients' organs in great detail. I can see the heart beating, blood flowing, lungs billowing, muscles contracting, and joints flexing. The book will begin with an organ system by organ system explanation of fitness, instead of the usual focus only on muscles.

LeMond writes:

I want you to unlock your full potential, just as I was able to do. You do not have to be the fastest, the strongest, the toughest, or even the smartest athlete in the world. But maybe you can be, with the right knowledge, enough willpower, and a little luck.

I lost 65 percent of my blood volume in the field. Shotgun pellets had ripped through my back and side, puncturing my lungs, liver, kidneys, and the lining of my heart. Despite the surgeons' best efforts, more than three dozen lead pellets remained embedded in my upper torso, including three in my liver and two in my pericardial lining. But I was alive. …

My first athletic love was not cycling, as some believe, but freestyle skiing. I grew up in Reno, Nevada, a bit of a wild child who spent as much time as possible outdoors. Tearing down the ski slopes of the Sierra Nevada Mountains was exhilarating. I found that I loved pushing myself, testing my limits.

In 1975, I attended a freestyle ski camp run by my hero Wayne Wong, who suggested I try cycling to stay in shape and build muscle onto my 14-year-old frame during the off-season. Bicycling is popular with skiers because it strengthens the same hip extensors, quadriceps, and calf muscles required in competitive skiing. I was sold on cycling as a way to exercise, and soon found it had many benefits for me beyond the physical.

I was a boy who just could not sit still. I had trouble focusing in school. Parents and educators then did not have the skill set to diagnose and cope with what we know now was a classic case of Attention Deficit Hyperactivity Disorder (ADHD). ADHD certainly was not the frequently medicated childhood disease it is today. My triumph over the symptoms was found atop two thin tires over many dusty miles. Even an hour of exercise cleared my head and sharpened my focus. I was transformed. …

When I was just 17 years old, I made a list of cycling goals for myself. They were certainly lofty goals, by anyone's standard, but even as a teenager I knew I possessed the dedication and skill to meet them. Here is my list from 1978:

  1. Win the Junior World Cycling Championship
  2. Bring home the Olympic gold medal in 1980
  3. Win the Professional World Cycling Championship by 23
  4. Win the Tour de France by 25

I met each of these goals except one, winning an Olympic medal.

In 1986, I won the Tour de France. I was the first and still the only American to claim the Tour de France trophy. …At the age of 25 years, I was on top of the world.

Nine months later, I was clinging to life in Sacramento, California.

My recovery did not go smoothly. …

There I was, the acknowledged best bicycle racer in the world, rapidly losing the physical accomplishments of my months and years of grueling training. Competing in the Tour de France has been likened to running a full marathon every single day for three weeks. The sheer brutality of the experience is hard to fully convey. Now, at the age of 25, at the pinnacle of my success, I was stretched out in a hospital room, wondering if I would ever be able to get on a bike again.

My French team sent me a letter expressing their relief that I had survived the shooting, and not-so-gently letting me know that my services would no longer be required. Kathy and I had been married for six years, had two sons, Geoffrey and days' old Scott, and had gritted our teeth through some tough early years in France. I struggled to concentrate on getting well, not on the difficulties facing our little family. It was a long time before I could walk even 100 feet without stopping to rest.

As I got stronger, my determination came back. I was going to reclaim my rightful place in the cycling world. It was going to take every single ounce of stubbornness and grit that I possessed, and every single thing I knew about body mechanics and proper training to find my way back to the Tour. The road back to Paris would be the greatest challenge of my life. …


Mark Hom, MD: "I was shocked when LeMond announced that his career was cut short by a mysterious illness called mitochondrial myopathy."

Mark Hom, MD, sports his cycling gear.One of the earliest and fondest memories of my childhood was learning to ride a bicycle. The freedom, mobility, and expansion of my world were new and exciting experiences at that highly receptive and impressionable age. …

My first bike was a blue Raleigh "Chipper" a single speed bike with a rear coaster brake, banana seat supported by a sissy bar, a kicked out front fork, and "chopper" style chrome handlebars. Designed to mimic the Harley Davidson motorcycles from the 1969 movie Easy Rider, that first bike vastly extended my world well beyond my neighborhood.

They say once you learn how to ride a bike, you never forget. That is because the brain (and the cerebellum in particular) makes new connections when you learn to ride. This rewiring of your brain or "muscle memory" can last your entire life. It was a simpler time then, and kids were expected to be physically active and playing outdoors, not surfing the Internet or gossiping on cell phones.

It was about this same age when I had my first exposure to cell biology in the 3rd grade. …That first day we used our microscopes to look at onion skin. They say odor induces the recording and recalling of long-term memory, and I clearly remember the strong smell of onions even decades later. Being one cell layer thick, the onion skin was a good demonstration of what constitutes a living plant cell (cell wall, cytoplasm, and nucleus). This was an epiphany. Before using that microscope, things were much simpler and easier to explain. I had assumed the onion skin would be featureless like a sheet of cellophane. I had already taken my toys apart and was disappointed to find them hollow and empty inside. However, this time seeing the array of cells and then the tiny parts inside each cell made me realize that the natural world was much more complex, fascinating, and worthy of study. This was probably the singular event that directed my life to the study of biology and eventually medicine. …

When I got to middle school, the boys' Physical Education (PE) class was divided into a high group and low group (which sounds awfully cruel by today's egalitarian standards). As a December child, I was nearly a year younger than some of my classmates, I was that much behind in adolescent growth and coordination, and I did not respond well to the pressure of team sports, so I was content when I was placed in the low group that first year. But at some point, I decided that I did not want to be a scrawny kid anymore. …

I began to bicycle as more than just a way to explore but also to improve my fitness. On a bulletin board (mind you a real bulletin board, not Craigslist or eBay), I saw an advertisement for a lightly used Schwinn Paramount 10-speed bike for $350. Although it drained every last penny of my life savings at the time, I had to have it. The Paramount was the ultimate ride of its day with hand-fitted chromed Nervex lugs, Reynolds 531 double butted steel tubing, and candy apple red paint. My best friend asked me why I was wasting my money on a bike when I would be getting my learner's permit to drive a car in a year.

Looking back, it is about this age that many discard the bicycle as a childhood toy and move on to other more adult interests. They say you never forget how to ride, but unfortunately too many people forgot how much fun it can be.

Undeterred, I rode every day after school and tried to get in as much training as possible before sunset. That meant strenuous, fast rides in a limited period of time. I sought out every challenging hill and climbed them as fast as I could. I remember riding so hard that my water bottles were empty, my shirt was drenched with sweat, and my legs felt like rubber bands when I carried the bike back down to storage in the basement.

One day while riding I looked down at my leg and saw a swelling going down the outside of my calf. Oh no, what had I done? I looked at the other calf and it was swollen too!

I later found out that I was developing my soleus muscles, the deep calf muscles normally hidden by the more obvious and superficial gastrocnemius muscles. In trained cyclists the soleus muscle in each calf becomes enlarged (hypertrophied) to be seen from the side. My quadriceps muscles had also hypertrophied and I was starting to take the shape of a cyclist. My heart was getting stronger too. …

I took every advanced biology class in high school and then majored in biology at Johns Hopkins University. I learned that the mitochondria in each of our cells generate the energy that drives muscular power and other vital functions in the body. At that level, we were taught the normal functions of mitochondria, and we wrongly assumed that they performed their task perfectly and unendingly, needing no special attention.

One book stood out at the time, The Lives of a Cell: Notes of Biology Watcher by Lewis Thomas (Bantam Books 1974). With a wide view of the biosphere and specific microscopic detail, Thomas showed that all life on Earth is intimately connected, no more so than how mitochondria came to be inside of our cells.

Although Lewis Thomas did not apply this synergy to sports, the energy that mitochondria supply to our cells powers our every athletic endeavor. …

When I took up cycling, bike racing was an obscure sport contested in faraway Europe with no local youth teams for me to join. There was not yet a modern American cycling hero of my own era. But then word got out that a blond-haired, blue-eyed American (with a French sounding name: LeMond) was beating the Europeans at their own game. He even won the most grueling physical contest in all of sport, the Tour de France (1986).

Greg LeMond and I are about the same age. While I was training to be a doctor, Greg was training to be the best athlete in the world. …

Because he was considered one of the most physically fit athletes of his era (undoubtedly having superior mitochondria), I and many others were shocked when LeMond announced that his career was cut short by a mysterious illness called "mitochondrial myopathy."

The shotgun pellets imbedded near vital organs were leaching elemental lead and poisoning his mitochondria. With his diagnosis, the general public (and many clinicians) began to realize that things could go wrong with mitochondria. …

Read the full preface


Related story

Read Dr. Hom's article for SciTechConnect: "Mitochondria: the source of inner power"


The Authors

Greg LeMondGreg LeMond is a pioneering bicyclist, three-time winner of the Tour de France (1986, 1989 and 1990), three-time World Cycling Champion (1979, 1983 and 1989), author, owner of, a bicycle technology innovator and a fitness expert. He is the founder of LeMond Fitness and a leader in the manufacture of the latest training equipment. He also works closely with leading sports physiologists (including Dr. Adrie Van Diemen, physiologist for Team Garmin) in the development of power training devices. In addition, he contributes in many cycling periodicals, most recently Cycling News.

Mark Hom, MD

Dr. Mark Hom is a Johns Hopkins University-trained biologist, an award-winning medical illustrator, an interventional radiologist applying high technology to the diagnosis and treatment of his patients, an educator of young doctors, and an avid fitness cyclist. Dr. Hom's work explains how the human body, various organ systems, and individual cells function in the biologic process of exercise. He is a member of the Department of Radiology at Virginia Commonwealth University.

They are the co-authors of The Science of Fitness, just published by Elsevier.

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