We recently published a paper in the Journal of Clinical Densitometry (Dengel et al., 2020) on body composition measures in over 590 NCAA Division I collegiate male and female track and field athletes. There is a wealth of data in the article and I encourage you to read it if you want more detailed information than is contained in this blog post. To make it easier to digest the information in the article I am going to talk about it in two separate blog posts. In this blog, I am going to focus on the men that were part of this track and field athletes’ database. In a companion blog post, I will focus on the women that are part of the track and field athletes’ database.
As many of you are aware track and field is unique in that it is made up of a number of events (i.e., shot put, sprints, long distance, pole vault, etc.) that require a variety of skills. In addition, many of these events that make up track and field favor athletes who have a very distinct body type and composition. In general, most track and field athletes try to maximize their fat to muscle ratio, however, the optimal total mass for each event is highly variable. For example, some events like shot put may favor athletes with large amounts of total mass as well as lean muscle mass while events such as distance running may want to limit the total body mass. Unfortunately, by trying to limit overall total mass, distance runners may actually put their bone health at risk. Therefore, it is not only important to monitor fat and muscle masses but also monitor bone health, which may be compromised. Dual X-ray absorptiometry (DXA) is the perfect tool to examine body composition in this population since it allows for the determination of fat and lean muscle masses as well as bone mineral density (BMD). DXA also allows for assessment of regional composition which is important in events that focus on a particular part of the body such as jumpers and throwers where asymmetries may develop due to training loads placed on the different regions of the body.
The article (Dengel et al., 2020) we recently published is unique in that it contains data from male and female collegiate track and field athletes from all of the events. So let’s look at the male track and field athletes that were scanned from 4 different NCAA Division I Universities and were classified into one of seven categories: Jumpers (i.e., long jump, triple jump, high jump) (n=28); Long Distance Runners (i.e., 5,000, 10,000 meters and 3,000 meter steeplechase) (n=104), Middle Distance Runners (i.e., 800 and 1500 meters) (n=27), Multi-Event Athletes (n=11), Pole-Vaulters (PV; n=21), Sprinters (i.e., 100, 200 400 meters, and 100, 110 and 400 meter hurdles) (n=54), and Throwers (i.e., shot put, discus, javelin) (n=29). Multi-Event Athletes were individuals who competed in the decathlon (i.e., 100 meters, long jump, shot put, high jump, 400 meters, 110-meter hurdles, discus, pole vault, javelin and,1500 meters). All DXA scans were done between September and December.
Physical characteristics of male collegiate track and field athletes (Table 1). The physical characteristics (i.e., age, height, weight, and body mass index [BMI]) of the male athletes by event are compared in Table 1. By design collegiate track and field athletes’ ages are similar across events. As you would expect, throwers were heavier than their counterparts. Based on standard body mass index (BMI) categories, sprinters, middle- and long-distance runners, jumpers, pole-vaulters, and multi-event athletes would be classified as normal (BMI: 18.5-24.9 kg/m2). Throwers, on the other hand, would be classified as obese (BMI: 30.0-34.9 kg/m2). The throwers being classified as obese is not too surprising and illustrates the problem with using BMI as a way to classify athletes, especially those athletes that are large and carry a lot of muscle mass. You see this same issue regarding misclassification of athletes using BMI when you look at professional football players, who also carry a large amount of muscle mass for their weight (Dengel et al., 2014).
Total body composition measures of male collegiate track and field athletes (Table 2).
In Table 2 the total body composition averages by event for the track and field athletes are presented. When these track and field athletes are classified by total percent body fat (%fat), male throwers would be considered overweight (%fat: 21-24%) while male sprinters, middle- and long-distance runners, jumpers, pole vaulters and multi-event athletes would be classified as good (%fat: 11-14%) (Jeukendrup & Gleeson, 2019). None of the male track and field athletes were considered athletic (%fat: 5-10%) (Jeukendrup & Gleeson, 2019). It is important to note that these classifications were based on two-component body composition methods (i.e., hydrostatic weighing and skinfolds), while the current study’s values were produced from a three-component body composition method (i.e., DXA). A two-component model of body composition has to assume mass of the bones while a three-component model of body composition actually measures the mass of the bones. This improves the accuracy of the three-component method body composition over the two-component method of body composition but also illustrates why there are differences between the two methods. Table 2 also contains the mass of the bones (BMC: bone mineral content) measurement values for male and female track and field athletes. Not surprising is the fact that both male long-distance runners had lower total BMC in comparison to their track and field counterparts, while male throwers had significantly greater total BMC than their counterparts. This illustrates the problem with assuming that the mass of bones for athletes or anyone is the same. There are a number of different factors that can affect the mass of bones [BMC] and therefore assuming everyone has the same BMC can lead to error in accuracy.
Total and regional measures of bone mineral density for male collegiate track and field athletes (Table 3). Mean total and regional measures of BMD for the sample are presented in Table 3. BMD is the amount of bone mineral in bone tissue. While BMC and BMD sound like the same thing, they are really two different measurements of bone. For example, two athletes, who weigh the same, but are different in regards to height, may have identical BMC values for their total body or for a particular region. However, the shorter athlete may have a higher total BMD when compared to the taller athlete at the same weight. BMD is often used clinically to assess risk of osteoporosis. While a very low BMD doesn’t predict a fracture, it may indicate if an individual is at a greater risk for a fracture. The data presented in Table 3 shows that the total BMD measurements for long-distance runners was significantly lower than BMD values for other track and field athletes. Throwers had significantly greater total BMD values compared to their male track and field counterparts. For most regional (i.e., spine, pelvis, leg, and arm) measures of BMD, throwers had significantly greater BMD values, while long-distance runners had significantly lower regional BMD values than their track and field counterparts.
What does it all mean? The main finding of this study is that there were significant total and regional body composition differences across position for male track and field athletes. These differences may be due to the unique demands of each position. Obviously, height plays a key role in a number of positions; however, an athlete’s total and regional body composition may make them more suitable for a particular event. As more and more athletic teams start to use DXA to measure and track body composition the information presented here provides normative data from which to compare these athletes. Finally, the data provided here serves as a jumping-off point for understanding player and positional norms in NCAA Division I collegiate male track and field athletes. Future studies are needed to determine seasonal changes in body composition.
For those that want more detailed information, I refer you to the original paper (Dengel et al., 2020), which this blog post is based on. I also urge you to read the companion blog post on NCAA Division I collegiate female track and field athletes. If you have questions regarding this blog post or the original paper (Dengel et al., 2020), that this blog post is based on please contact the corresponding author Dr. Don Dengel (e-mail: denge001@umn.edu).
References
Dengel DR, Bosch TA, Burruss TP, Fielding KA, Engel BE, Weir NL, Weston TD: Body composition of National Football League players. Journal of Strength and Conditioning Research 28(1):1-6, 2014.
Dengel DR, Keller KA, Stanforth PR, Oliver JM, Carbuhn A, Bosch TA: Body composition and bone mineral density of division 1 collegiate track and field athletes, a consortium of college athlete research (C-CAR) study. Journal of Clinical Densitometry 23(2):303-313, 2020.
Jeukendrup A, Gleeson M. 2019 Sport Nutrition. 3rd ed. Champaign, IL: Human Kinetic; 2019.
About the Author
Donald Dengel, Ph.D., is a Professor in the School of Kinesiology at the University of Minnesota and is a co-founder of Dexalytics. He serves as the Director of the Laboratory of Integrative Human Physiology, which provides clinical vascular, metabolic, exercise and body composition testing for researchers across the University of Minnesota.