|Can You Go the Distance...to Better Health?
Michelle G. Kulovitz and Len Kravitz, Ph.D.
Article Reviewed: Williams P.T. (2009). Lower prevalence of hypertension, hypercholesterolemia, and diabetes in marathoners. Medicine & Science in Sports & Exercise. 41(3), 523-529.
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 will really make a difference in a person's overall health. Does that extra mileage reduce and/or help to prevent metabolic syndrome, a cluster of cardiovascular disease risk factors that are associated with elevated blood triglycerides, hypertension, and insulin resistance? Williams (2009) surveyed over 100,000 men and women runners to learn more about this intriguing association.
All participants (62,284 male and 45,040 female non-smoking runners) were surveyed nationally through races and magazine media with a two-page questionnaire (created for the National Runner's Health Study) which asks information on running history, weight history, diet, current weekly intakes of alcohol, red meat, fish, fruit, vitamin C, vitamin E, aspirin, cigarette use and specific medications (for blood pressure, thyroid conditions, cholesterol levels, or diabetes). Runners were excluded from the study if they smoked or were strict vegetarians. Running distance and marathon participation was determined by survey questions and a diary of miles per week. Subjects reported only running mileage and did not include other physical activities done at leisure.
Annual marathon participation showed that men had significantly lower odds for using any metabolic syndrome medications than non-marathon running men and 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 anti-diabetic medications than non-marathon runners. The slower running males and females (determined from marathon finish times and reported 10-km performance) had greater use of hypertension and high cholesterol medications than did their faster running counterparts. Also, longer training runs were associated with a significant reduction in all medications for men, but not for women.
What are some unique characteristics of marathon runners?
Much research has been conducted to better understand the physiological and metabolic adaptations of marathoners. Marathoners are different from recreational short-distance runners in the way that their bodies use nutrients for fuel. Spriet (2007) expands 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. Sprite continues that marathon runners become highly adapted to use fat as a fuel, especially during training. Hawley and Spargo (2007) clarify that these muscle metabolic adaptations are site specific in the muscles engaged in the training (lower limbs), and not seen in other non-trained muscles in the body. Distinctively, elite marathoners (finish times between 2:05:00 and 2:20:00) who compete at 80-90% of their aerobic capacity (VO2 max) are capable of utilizing carbohydrate almost exclusively during a marathon (Spriet, 2007). Williams (2009) adds that female and male marathoners may also be genetically endowed with greater exercise capacities due to a more developed aerobic metabolism in the cells of lower body muscles. He suggests that this genetic factor may positively impact the lower risks of hypertension, diabetes and abnormal cholesterol levels observed in marathoners. Williams continues that marathoners are reported to have approximately one half the total fat mass as compared to their BMI-matched sedentary controls. Williams' research also suggests that marathon runners have a diet somewhat different from shorter-distance runners. Marathoners are found to eat more fruits per week and less servings of red meat per week.
So, Are We Made to Run?
Bramble and Lieberman (2004) suggest that 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) from our legs can generate considerable force quite economically (without considerable utilization of energy). This spring-like mechanics 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 4 times body weight. The premise follows that the bones grow and remodel throughout life to adapt to the mechanical stresses placed upon them from the environment or 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, and 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.
Any Insight on the Psychology of Marathoners?
Raglin (2007) summarizes that marathoners tend to be less introverted then non-athletes and 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 individual. Thus, specific attributes of a person may predispose her/him to choose to become an endurance exerciser and/or marathoner. Raglin also highlights that elite marathoners are also highly motivated to achieve and driven primarily by their own intrinsic satisfaction and internal reward system.
Implications for Exercise Professionals
It is well-known that aerobic exercise has numerous health benefits and will markedly improve a person's overall health (See IFJ 2007, volume 4(9); The 25 most significant health benefits of physical activity and exercise). Recently, high intensity interval training programs (e.g., HIT, HIIT, SIT) have come to the forefront of research and practical application as these programs illicit numerous metabolic, physiological and health adaptations similarly observed from traditional endurance programs (See IFJ 2009, volume 6(4); Calorie burning: It's time to think "outside the box). Additionally, as summarized in this research article by Williams (2009), going the distance makes a difference. Greater total annual mileage was shown to have meaningful health promoting benefits for men and women for managing and treating high blood pressure, high cholesterol, and diabetes. As fitness professionals we now know that increasing, not only the intensity, but the duration of exercise will give clients a greater possibility of keeping these common metabolic diseases under control (with less medication). Perhaps as we strive to enhance our student and client base, many exercise professionals will consider developing endurance-related clubs, groups and camps (i.e., marathon clubs, triathlon teams, running camps) of interested participants.
Brambel, D.M. & Lieberman, D.E. (2004). Endurance running and the evolution of Homo. Nature. 432, 345-352.
Hawley, J.A. & Spargo, F.J. (2007). Metabolic adaptations to marathon training and racing. Sports Medicine. 37, 328-331.
Raglin, J.S. (2007). The psychology of the marathoner: Of one mind and many. Sports Medicine. 37, 404-407.
Spriet LL. (2007). Regulation of substrate use during the marathon. Sports Medicine. 37:332-336.
Michelle G. Kulovitz, BS. is a masters candidate in the exercise science program at The University of New Mexico (Albuquerque). She earned her bachelors of science degree in exercise biology from the University of California, Davis and has research interests in physical performance development, exercise for preventative health, neuromuscular physiology, and sports nutrition.
Len Kravitz, Ph.D., is the Program Coordinator of Exercise Science and Researcher at the University of New Mexico where he won the "Outstanding Teacher of the Year" award. Len was recently honored with the 2009 Canadian Fitness Professional Specialty Presenter of the Year award and chosen as the American Council on Exercise 2006 "Fitness Educator of the Year. He also has received the prestigious Canadian Fitness Professional Lifetime Achievement Award.