Is there something about marathoners that makes them physiologically and medically different?
Williams, P.T. 2009. Lower prevalence of hypertension, hypercholesterolemia, and diabetes in marathoners. Medicine & Science in Sports & Exercise, 41(3), 523-29.
Although marathoners train and compete for numerous reasons, a common question of several running advocates and scientists is whether the longer distances performed in marathon preparation really make a difference in a person’s overall health. Does that extra mileage reduce and/or help prevent metabolic syndrome, a cluster of cardiovascular-disease risk factors that are associated with elevated blood triglycerides, hypertension and insulin resistance? Williams (2009) surveyed more than 100,000 men and women runners to learn more about this intriguing association.
All participants (62,284 male and 45,040 female nonsmoking runners) were surveyed nationally through races and magazine media with a two-page questionnaire (created for the National Runners’ Health Study). The survey elicited information on running and weight history; diet; current weekly intakes of alcohol, red meat, fish, fruit, vitamin C, vitamin E and aspirin; cigarette use; and use of specific medications (for blood pressure, thyroid conditions, cholesterol levels or diabetes). Runners were excluded from the study if they smoked or were strict vegetarians. Both in the survey and in a diary of miles per week, the runners provided information about running distance and marathon participation. Subjects reported only running mileage and did not include other physical activities done at leisure.
The results showed that men who participated in annual marathons had significantly lower odds for using any metabolic syndrome medications than non-marathon-running men. The odds were even lower if the men ran more than one marathon per year. Women marathoners also had a lower prevalence of taking cholesterol-lowering and antidiabetic medications than women who did not run marathons. Among both males and females, the slow runners (determined from marathon finish times and reported 10K performances) reported greater use of hypertension and high-cholesterol medications than the faster runners. Also, longer training runs were associated with a significant reduction in all medications for men, but not for women; among females, greater cardiorespiratory fitness lowered medication use more effectively than just doing longer endurance runs.
Much research has been conducted to better understand the physiological and metabolic adaptations of marathoners (see Figure 1). Marathoners are different from recreational short-distance runners in the way their bodies use nutrients for fuel. Spriet (2007) posits that a marathoner must supply enough energy for sustained vigorous physical activity for 2–5 hours using fat and carbohydrate from the adipose tissue, muscle and liver stores. The demands of marathon training increase the muscle cells’ ability to store triglycerides. This is the dominant site (intramuscular fat droplets) for fat mobilization and utilization during endurance training.
Spriet goes on to say that marathon runners become highly adapted to using fat as a fuel, especially during training. However, Hawley and Spargo (2007) note that the observed metabolic adaptation is site-specific to the muscles engaged in the training. Thus, the enhanced adaptation is seen in the lower-limb muscles of marathoners, but not in their upper-body (nontrained) muscles.
Williams (2009) adds that female and male marathoners may also be genetically endowed with greater exercise capacities by having a more developed aerobic metabolism in the cells of lower-body muscles. He suggests that this genetic factor may itself confer lower risks of hypertension, diabetes and abnormal cholesterol levels. Williams continues by saying that marathoners are reported to have approximately one-half the total fat mass of their body mass index (BMI)–matched sedentary controls. His research also suggests that marathon runners have a diet somewhat different from shorter-distance runners, as marathoners have been found to eat more fruit and less red meat per week.
Bramble and Lieberman (2004) suggest that, as humans, we have several biomechanical and physiological characteristics that allow us to perform remarkably well in endurance running. They propose that the mass-spring mechanics of running (i.e., the ability to store and release energy when striding) can generate considerable force quite economically (without considerable energy expenditure). This promotes faster and potentially longer running bouts. From a skeletal health perspective, Bramble and Lieberman note that running exposes the bones to vertical ground reaction forces that may be up to four times body weight. The premise follows that the bones grow and remodel throughout life to adapt to the mechanical stresses placed on them from the environment or the activity of the individual. Thus, with endurance training, the challenged bones accommodate to the loads imposed on them by altering their mass, shape and strength, thus helping to prevent osteoporosis. Bramble and Lieberman also note that humans have very well developed thermoregulatory and respiratory systems that allow us to capably complete sustained endurance exercise bouts.
Raglin (2007) summarizes that marathoners tend to be less introverted than nonathletes and to have more desirable health profiles. He states that marathoners generally have less anxiety, depression and neuroticism, and score higher in emotional stability. Interestingly, these positive psychological traits are not a result of the marathon training but appear to be innate to the individuals. Thus, specific attributes of certain people may predispose them toward endurance or marathon exercise. Raglin also notes that elite marathoners are highly motivated to achieve and are driven primarily by their own intrinsic satisfaction and internal reward system.
It is well-known that aerobic exercise yields many health benefits and will markedly improve a person’s overall health (see “The 25 Most Significant Health Benefits of Physical Activity & Exercise,” by Len Kravitz, PhD, October 2007 IDEA Fitness Journal).
Recently, high-intensity interval training programs (e.g., HIT, HIIT or SIT—sprint interval training) have come to the forefront of research and practical application, as these programs elicit numerous metabolic, physiological and health adaptations similar to those observed from traditional endurance programs (see “Calorie Burning: It’s Time to Think ‘Outside the Box,’” by Len Kravitz, PhD, April 2009 IDEA Fitness Journal). Additionally, as summarized in Williams’s research, going the distance makes a difference. For men and women alike, greater total annual mileage was shown to have meaningful health-promoting benefits for managing and treating high blood pressure, high cholesterol and diabetes. As fitness professionals, we now know that increasing not only the intensity but also the duration of exercise will give clients a greater possibility of keeping these common metabolic diseases under control (with less medication).
As we strive to enhance our student and client base, many exercise professionals might consider developing endurance-related clubs, groups and camps (i.e., marathon clubs, triathlon teams, running camps) for interested participants. As is noted by many marathoners and endurance enthusiasts, the rhythm of running provides that refreshing and often needed solace within the hectic events of daily life. Enjoy your run!