There’s always something new to learn about exercise and exercise programming. The human body has many mysteries to uncover through both science and experience. The science and research behind exercise support your mission and business as a personal trainer. Getting more familiar with it strengthens your relationship with a healthy lifestyle, which trickles over to your clients. Whether they care about the details or not.

Everybody knows exercise is beneficial to our health, assuming the programming is appropriate for the individual. While it is true that the majority of those whom we help on a daily basis are only interested in generating visible results, there are always a few who truly want to know the mechanism behind what goes on within the human body to effect such desirable changes.

The truth is that, to date, scientists and athletes alike do not fully understand exactly what’s happening behind the scenes. But, we know a lot. For you and your clients who care, here is what we know. In a nutshell.

History of Exercise Programming and Science

In the early 1900s, with the rise of modern surgery and the evolution of various pharmaceuticals, the practice of medicine shifted its focus from the prevention of disease to its treatment. The quest for “why” was lost somewhere along the line, as individuals became much more invested in turning to medicinal and surgical solutions as opposed to better self-care.

Today, a significant portion of our population strives to avoid intervention of this sort, and has become increasingly curious as to how we can better activate our bodies to stave off illness before it starts.

In an effort to gain perspective, and answers to basic exercise-related physiological questions, a team of doctors collaborated and combined their respective fields of expertise. The team was comprised of neuroscientist Judy Cameron, Ph.D., professor of psychiatry at the University of Pittsburgh School of Medicine; Tommy Boone, Ph.D., a board-certified exercise physiologist; and Edward Laskowski, M.D., co-director of the Mayo Clinic Sports Medicine Center. We now have a clearer comprehension of those fitness and health aspects that transpire within the body.

Exercise is a Brain Booster

Scientists do not know exactly why exercise changes the structure and function of the brain for the better, but it is currently an area of active research. To date, it has been found that exercise improves blood flow to the brain, feeding the growth of new blood vessels and even new brain cells, courtesy of the protein known as brain-derived neurotrophic factor, or BDNF. This protein appears to trigger the growth of new neurons, and helps repair and protect brain cells from the degeneration that we often observe with age.

The Energy Equation

The science behind energy systems has been documented for years. When fueling muscle tissue and expenditure, the human body calls upon glucose. This is simply sugar that the body has stored, derived from the breakdown of foods we eat. After the digestive process occurs, glucose becomes converted to glycogen, which is its preferred storage form. Glycogen stays on high alert in the body, ready to be drawn upon as we contract muscles and engage in dynamic sports.

Another energy system the human body utilizes requires adenosine triphosphate, or ATP. Similarly to glucose, the body can only store small amounts of ATP. After quickly using up these supplies, the body requires extra oxygen to create an additional supply. As a result, extra blood gets pumped to the exercising muscles, in an effort to deliver that additional O2. In the absence of sufficient oxygen, lactic acid will accumulate and cause muscle fatigue. With a sufficient oxygen supply, lactic acid is typically flushed from the body within 30 to 60 minutes upon completion of a workout.

Sweaty Science

An interesting scientific principle that has been researched with regard to exercise is the body’s cooling mechanism, especially during physical exertion. If we consider the human body as a complex machine, its “engines” produce heat as exercise ensues. Without an adequate cooling system, we would be at risk of severely overheating on a regular basis. To prevent this, blood vessels in the skin dilate, increasing blood flow to the skin. The built-up heat then dissipates through the skin into the air.

The skin cells contain 2 types of glands that are responsible for necessary sweat production. One type is known as eccrine glands, turned on by a signal from our brain’s hypothalamus. Once recruited into action, these glands will produce odorless perspiration, a mixture of water, salt and other electrolytes, directly onto the skin’s surface. As this sweat evaporates into the air, the cooling mechanism lowers the body’s temperature. This helps to explain why we can be so hot and sweaty during a workout, yet as soon as the sweat dissipates, we often grab for a warm-up jacket due to a slight chill.

The second type of gland involved in this miraculous engine cooling process is the apocrine gland group. These glands are typically found in areas of the body where hair grows: scalp, armpits and groin. The sweat produced in these areas has a higher fat content than that produced by the eccrine glands. When activated under emotional as well as physical stress, the sweat is broken down by the bacteria that reside on the surface of the skin. This breakdown can contribute to the odor we commonly associate with perspiration.

Origins of the Overload Principle

The exact mechanism by which exercise enhances the body’s strength remains unclear, but its basic principles are understood. Hypertrophy, or the enlargement of cells, and neural adaptations that enhance nerve-muscle interaction both are key components. Muscle cells that are treated to regular bouts of exercise, followed by periods of rest with sufficient dietary protein, will undergo hypertrophy as a response to the stress of training. This is what we commonly refer to with our clients as “the overload principle”.

The neural basis of muscular strength development involves the body’s ability to recruit additional muscle cells in a simultaneous manner, a process referred to as synchronous activation. This is in contrast to the firing pattern seen in untrained muscle, where the cells take turns firing in an asynchronous manner. This neural adaptation facilitates significant strength gains.

Since the human body is affected by more than simply the generation of lean muscle mass, scientists have delved into the mechanisms by which debilitating illnesses can be prevented or reversed simply through the introduction of exercise. According to Dr. Mark Tarnopolsky, a genetic metabolic neurologist at McMaster University in Ontario, exercise can be used as “medicine” for even the sickest patients. In 2011, Dr. Tarnopolsky and his team studied mice that suffered from a genetic disease that caused premature aging.

Over the course of 5 months, half of the mice remained sedentary, while the other group ran 3x/week on a miniature laboratory treadmill. At the conclusion of the study’s time frame, the sedentary mice were barely clinging to life. Any fur remaining on their frames turned coarse and gray. Muscle atrophy was apparent, as were weakened hearts and thinning skin. Dr. Tarnopolsky noted how “the mice were shivering in the corner, about to die.”

In sharp contrast, the group of mice that had been made to exercise appeared nearly indistinguishable from healthy mice, in spite of their dreadful genetic condition. Their coats were sleek and black, they ran around their cages, and even possessed the ability to reproduce. “We almost completely prevented the premature aging in the animals,” Tarnopolsky reported. He and his team concluded that if there was a drug on the market that could improve our health as effectively as exercise, it might possibly be the most highly prized pharmaceutical on the planet.

The Gym Versus The Pharmacy

Many recent studies have focused on a unique marker of inflammation known as C-reactive protein. Research has demonstrated that previously sedentary individuals who were placed on various 3-6-month exercise programs experienced on average a 30% dip in their C-reactive protein levels – about the same drop as one would see when taking statins, a class of commonly prescribed cholesterol and inflammation-lowering drugs. It would seem as though exercise might be as effective as medication in tamping down inflammation, one of the key risk factors for cardiovascular disease.

Exercise also boosts cardiovascular health by decreasing the number of fatty molecules in the blood (triglycerides) that are associated with arterial plaque build-up. Physical activity has likewise demonstrated the ability to reduce the particle size of low-density lipoprotein (LDL) in the blood, and increase amounts of high-density lipoprotein (HDL). This, in turn, potentially can translate to less artery clogging.

In addition to muscles, our bones can become stronger when forced to bear more weight than normal. Any time a load is placed upon an arm, shoulder, leg or spine, muscular contractions exert forces upon the bones that support these body parts. Such force stimulates the bone to maintain or even build new tissue. Scientists have yet to figure out exactly why this occurs; however, it has been postulated that the process of exercise triggers bone-building cells known as osteoblasts to increase bone formation. Once again, research in this area is actively occurring.

Is Seeing Necessary For Believing?

Returning to the clients who only want to see results but do not necessarily want to understand the mechanisms involved in gaining lean muscle mass and improving health, it is important that we understand their viewpoint. There is much support in the fitness community for what we call an evidence-based approach to exercise. Such a theory makes use of research studies but also relies heavily on a trainer’s clinical expertise, his experience, and a client’s personal preferences for exercise modalities.

Fitness websites and community blog boards are resplendent with “evidence” that certain exercises if executed correctly, will indeed lead to results. For example, readers often conclude that if enough bodybuilders report increases in lower body mass and strength from a regimen of deadlifts and squats, this must, in fact, be the only way to train. These results-focused athletes reason that such anecdotal evidence surely must not be questioned, and thus embark upon their own deadlift/squats routine with the goal of adding lean muscle mass and power to their quads and hamstrings.

Is there anything problematic about this path, or will it ultimately lead to the same results as the scientific-understanding route? While there is not a danger, so to speak, in embracing a professional’s expert opinion based on his experience, it is also prudent for a novice weightlifter to grasp the concepts behind the movements.

Ronald Sigal, a clinical epidemiologist working at the Ottawa Health Research Institute in Canada, has this to say: “It is very likely that there are differences in the extent to which individuals respond to exercise, just as there are in responses to medications.”

Armed with this knowledge, we realize that Athlete #1’s response to the aforementioned leg workout may, in fact, differ significantly from the results observed by Athlete #2. By grasping the scientific explanations, Athlete #2 may be able to stave off any ensuing frustration, and comprehend that every human body differs greatly when it comes to exercise and its role in health management.

Staying current with the science behind the exercise is one way to earn the respect and attention of science-minded medical professionals you’re looking to gain referrals from. It’s also the path to earning the trust of potential clients who want evience based programming.










Cathleen Kronemer

Cathleen Kronemer

Cathleen Kronemer is an NFPT CEC writer and a member of the NFPT Certification Council Board. Cathleen is an AFAA-Certified Group Exercise Instructor, NSCA-Certified Personal Trainer, ACE-Certified Health Coach, former competitive bodybuilder and freelance writer. She is employed at the Jewish Community Center in St. Louis, MO. Cathleen has been involved in the fitness industry for over three decades. Feel free to contact her at She welcomes your feedback and your comments!