BEVERLY HILLS—Many have long been in awe of what athletes can achieve, with records being broken every year from powering at impossibly high speeds over grueling long distances in marathons, to achieving incredible strength and dynamic agility through the demanding world of extreme triathlons, cross country skiing, cycling and swimming. It seemed that if you weren’t “born with it” then you simply didn’t have “it” - “it” being, of course, the X-factor of talent which results in a passport to success as a top performing athlete. Apparently, though, that je ne sais quoi of the fitness world does come with the genetic tag, after all. New research has identified a key negative gene regulator for endurance, indicating that athletes who are able to perform to a high endurance level in sports which demand performance from the muscles over an extended period of time do not have the gene code present.

Photo by Jessica Huff

Of course, our genetic make-up can determine much of how we act, react and adapt to challenges throughout our daily lives. When it comes to excelling at our chosen sports, however, genes will ultimately give the capacity to push and achieve the very best we can from our bodies. Body type, muscle size and hypertrophy potential, physiological build, overall lung capacity, physiological strength, flexibility, and muscle fiber composition and ratio are all defined in the gene patterns we are born with. Perhaps most importantly of all, particularly for the performing athlete, is the genetic make-up responsible for the heart, determining the size and strength of the heart muscle, and how much blood (and hence oxygen) can be transported to the body’s muscles and tissues during physical demand according to the heart’s efficiency and potential for growth. The ability of muscles to take in and use oxygen and adenosine triphosphate (ATP) as energy is also a genetic restriction. Let us understand that there are two types of muscles in the body: those made of fast twitch muscle fibers, and those comprised of slow twitch muscle fibers. Fast muscles are used for quick immediate contracting movement (speed), whilst slow muscles are used for contracting movement over a steadier, longer period of time (endurance).  The gene codes for the protein Interluekin-15 receptor-alpha (IL15-Ralpha) define the function of fast twitch muscle fibers.

The Perelman Medical School at the University of Pennsylvania published their recent findings in the Journal of Clinical Investigations. Their results showed when the gene code for IL15-alpha was absent, there was a greater resistance to fatigue and increased aerobic capacity in fast twitch muscles. Tejvir S. Khurana, MD, PhD, professor of Physiology, highlighted that the subject was able to run over six times longer distances with slower contractions and less muscle fatigue. She concluded: "This has wide ramifications for various aspects of muscle biology ranging from athletics to treating muscle and metabolic diseases." The substantial link between the gene and elite athletes supports the notion that genetic make-up gives an individual a distinct competitive advantage. Results published further indicated “the loss of IL15-R alpha induces a shift in how energy is burned in fast muscles, substantially increasing fatigue resistance and exercise capacity. Morphologically, the fast muscles with the gene absent had a greater number of muscle fibers, smaller fiber areas, and a greater number of nuclei per fiber. The study also found significant associations between the gene and elite endurance athletes and hence supports the possibility that these athletes had a genetic predisposition or advantage.”

The research comes with some other significant results for the field of health. IL15-R alpha is known to be vital to immune response, and this shows a substantial potential breakthrough in improving the ability of muscles to perform under difficult conditions such as obesity, disease, diabetes and heart problems. Emidio E. Pistilli, PhD, professor in the Division of Exercise Physiology at the West Virginia School of Medicine, explained “We found a previously unrecognized role for IL15R-alpha in defining muscle function, and manipulation of this gene has the potential to improve muscle performance in disease states including metabolic disorders, obesity, and aging." The exact role of the function of muscle tissue has not yet been clearly defined and ongoing research is being carried out.

Our genes determine the way we respond to exercise, diet, training methods and psychological stimulation. Some athletes may respond more effectively to endurance training than others, so even though one may not have the desired negative presence of IL15-R alpha, they may respond better than others who do have it. Yet, genetic make-up aside, the application of the correct training methods and diet can increase balance, agility, reflexes, and overall muscular performance - all factors which will make or break an Olympic-level athlete at the top of their game. Mental stimulation, motivation, determination, repulsion of anxiety, stress and competition related nerves all play their role. So in conclusion, yes, genetic make-up does play a role in the athlete’s success, but there remain many other important factors that determine the superiority of an athlete’s performance at the top. Hard work, strict training, an excellent diet and a strict mental focus is ultimately what separate the strong from the strongest, and the fast from the fastest. You can be lucky enough to be born with the basic tools to get you there, but in the end, it is how you use them that really counts.

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