Medial Elbow Joint Space Decreases with Forearm Flexor Contraction – Implications for Elbow Joint Stability & Ulnar Collateral Ligament Injury

Research Team Members: Brett Pexa (PhD Student in Human Movement Science), Dr. Eric Ryan and Dr. Joseph Myers

elbow valgusWhy did you do this study?

Ulnar collateral ligament (UCL) tears, or commonly called ‘Tommy John’ is the tearing of the ligament on the medial portion, or inside, of the elbow. This injury is becoming more common in baseball players, and happening in younger and younger athletes. The ulnar collateral ligament is commonly injured during baseball participation due to the high loads and repetitive stress it experiences during throwing. Baseball pitching exerts a tremendous amount of force on the ulnar collateral ligament and the entire medial elbow. The forces during baseball pitching are up to three times higher than what the ulnar collateral ligament can withstand before tearing. The muscles in the forearm contract to help absorb this force, and previous research in cadaveric and computer models support this hypothesis. The use of diagnostic ultrasound is a quick and reliable way to image living tissue, we are able to look at the medial elbow joint in living tissue to assess how finger and forearm flexor activity can assist in protecting the medial elbow joint.

What did you do and what did you find in this study?

Pexa1

Ultrasound image of medial elbow. Dotted line represents the medial elbow joint space, which was the main measure in this study. (ME = medial epicondyle; TR = trochlea; ST = sublime tubercle; UCL = ulnar collateral ligament)

We measured the medial elbow under 3 different loading conditions: unloaded, loaded, and loaded-contracted. For the unloaded condition, the elbow was at rest. For the loaded condition, we added a cuff weight to the wrist to create stress on the medial elbow joint that mimics baseball pitching. Finally, for the loaded-contracted condition, we added a cuff weight and had the participants grip against a handgrip dynamometer. Our main outcome measure was medial elbow joint space, and this variable was the distance between the humerus (upper arm bone) and the ulna (lower arm bone). The ultrasound machine was placed in a specific location over the medial elbow and 4 specific structures were identified: The medial epicondyle, the ulnar collateral ligament, the trochlea of the humerus, and the sublime tubercle of the ulna (Figure below). Once all 4 of the structures were identified, an image was captured on our ultrasound machine. During the loaded-contracted condition, we made sure all 4 structures were present and the participant was maximally contracting against the grip dynamometer in their hand. The distance from the trochlea to the sublime tubercle was then measured and assessed across conditions. We found that the medial elbow joint space during the loaded condition was larger than the unloaded condition, and the joint space was smaller in the loaded-contracted condition than the loaded condition. This confirmed our hypothesis that the medial elbow joint does assist in absorbing force from the UCL to protect it and prevent it from tearing.

Pexa2

Elbow joint space across 3 loading conditions. The loaded-contracted condition was significantly lower than the loaded condition, indicating that the forearm muscles decrease the medial elbow joint space and subsequently the amount of stress on the medial elbow.

How do these findings impact the public?

These findings help stress how the forearm flexor muscles helps protect the ulnar collateral ligament. With UCL injuries on the rise in professional baseball and happening to younger athletes, rehabilitation and training regimens should address strength of this muscle group. Exercises that address grip strength, wrist strength, and even elbow strength should be added in preseason programs. High function of this muscle group is imperative to health of the UCL and medial elbow joint in baseball pitchers. Future research will investigate how fatigue of this muscle group affects its protective capability of the UCL.

 

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Examining the actual implementation of evidence-based sports injury prevention programs: A look at USA Football’s Head Up Football educational program

Why did you do this study?

Given the concerns over youth participation in contact sports, particularly football, I felt it was important to examine manners in which we could provide children with opportunities to participate in such sports while consideration what safety precautions could be in place.

zack1The Heads Up Football (HUF) educational program was created by USA Football in 2015 and includes: hands-on training of equipment fitting and tackling technique; strategies for reducing player-to-player contact (drill development); and education related to the recognition and prevention of concussion, exertional heat illness, and sudden cardiac events.  Each USA Football league (i.e., a group of youth football teams within a single organization that play each other across a season) was required to have a designated “Player Safety Coach” (PSC).

This Player Safety Coaches were nominated by each league and were typically well-respected coaches or administrators.  USA Football would train these Player Safety Coaches on HUF components, who would then return to their leagues to share this information to the coaches, parents, and players. This was done by:

  1. Having coaches undergo coaching certification through an online educational program
  2. Facilitating a clinic at the beginning of the season to introduce and/or review the components of the HUF educational program for all coaches and parents
  3. Having an on-field presence at all league-sanctioned practices to reinforce HUF components

zack2Previous research I had conducted had found that youth football leagues that had adopted HUF had fewer incidences of head impacts in practice1 and lower practice injury rates, particularly when used in conjunction with practice contact restriction guidelines.2  USA Football was satisfied with these findings and began promoting HUF as an evidence-based prevention program.

However, despite these promising findings, I worried how well actual implementation would be outside of ideal research settings that my study designs had created.  Thankfully, USA Football was also invested in this research and provided full support.  Thus, my study examined how coaches actually implemented HUF in their leagues.3

My research team included:

  • Emily Kroshus, ScD, MPH; Seattle Children’s Research Institute in the Center for Child Health, Behavior and Development in Seattle, WA
  • Joseph G. L. Lee, PhD, MPH; Department of Health Education and Promotion in the College of Health and Human Performance at East Carolina University in Greenville, NC.
  • Susan W. Yeargin, PhD, ATC; Department of Exercise Science in the Arnold School of Public Health at the University of South Carolina in Columbia, SC.
  • Thomas P. Dompier, PhD, ATC; Datalys Center for Sports Injury Research and Prevention in Indianapolis, IN.

What did you do and what did you find in this study?

Data were collected via an online questionnaire that was completed by 1316 youth football coaches from leagues across the US that were using HUF.  Participating coaches were asked to answer questions related to whether they had:

  • Completed the online coaching certification program;
  • Attended the safety clinic at the beginning of the season;
  • Regular saw their league’s Player Safety Coach on-site during league-sanctioned practices; and
  • Implemented the components of HUF.

Our findings were as follows:

  • All but two coaches (99.8%) completed the online coaching certification program.
  • Nearly half of coaches (44.8%) did not attend the Player Safety Coach safety clinic at the beginning of the season. The three most common reasons for not attending were: they were not aware the clinic was offered; they were too busy with other personal activities; and the time of the clinic was not convenient.
  • Over a quarter of coaches (25.9%) reported not seeing their league’s Player Safety Coach on the field on a regular basis.
  • Despite this, a large majority of coaches described their implementation of programming as “good” or “very good.”
  • However, 0% of coaches reported that they did not have AEDs at practice and game facilities.

In addition to these findings, our research team also considered our previous research that had found that completion of the online coaching certification program had varied by socio-economic characteristics of the communities in which these leagues were located.4  Leagues in communities with a higher percentage of families living below the poverty line and a smaller percentage of non-Hispanic white residents tended to have leagues with smaller percentages of HUF-certified coaches.  The Southern area of the US also had lower certification levels.

zack3

How do these findings impact the public?

It is important for the public to critically appraise research that pertains to the health and safety of their children while they play sports.  Although findings related to HUF are promising, there are still many opportunities to improve this injury prevention program.  One such way is ensuring that implementation is consistent across the many leagues using HUF, particularly those in areas in the South and/or with lower socio-economic status.

As a result, while the public should commend the work of sport organizations that aim to develop these injury prevention programs, they should also continue to advocate for continued improvements.  Pro-equity efforts are needed to help create opportunities to improve health outcomes for ALL players, regardless of location or socio-economic status.  As more research is provided to the public, parents can then make informed decisions about whether to allow their children to participate in these sports.

References

  1. Kerr ZY, Yeargin SW, McLeod TCV, Mensch J, Hayden R, Dompier TP. Comprehensive Coach Education Reduces Head Impact Exposure in American Youth Football. Orthopaedic Journal of Sports Medicine. 2015;3(10):2325967115610545.
  2. Kerr ZY, Yeargin S, McLeod TCV, et al. Comprehensive coach education and practice contact restriction guidelines result in lower injury rates in youth American football. Orthopaedic Journal of Sports Medicine. 2015;3(7):2325967115594578.
  3. Kerr ZY, Kroshus E, Lee JG, Yeargin SW, Dompier TP. Coaches’ Implementation of the USA Football “Heads Up Football” Educational Program. Health Promotion Practice. 2017:1524839917700398.
  4. Kroshus E, Kerr ZY, Lee JG. Community-level inequalities in concussion education of youth football coaches. American Journal of Preventive Medicine. 2017;52(4):476-482.

Neural and Muscular Contributions to the Age-Related Reductions in Rapid Strength

We begin the 2017-18 academic year’s EXSS Impact Blog post with a recent publication by Gena Gerstner, who is a PhD student working under the mentorship of Dr. Eric Ryan.  The findings from this research were recently published in the July 2017 issue of Medicine and Science in Sports and Exercise.

The research team supporting this study include multiple masters and PhD students from the Exercise and Sport Science and Human Movement Science graduate programs, respectively.

Why did you do this study?

This is all you now!It is projected that by 2030 the number of older adults aged 65 and over will represent nearly 20% of the total population.  A large percentage of older adults experience functional limitations with everyday tasks and a high incidence of injuries resulting in a significant economic burden.  For example, one out of three older adults experience a fall each year, an event that often times results in accelerated deteriorations in health.

Aging is associated with reductions in maximal and rapid strength, with rapid strength production appearing to decrease to a greater magnitude. These changes are related to mobility limitations and the increased risk of falling. Multiple studies have reported age-related reductions in maximal voluntary isometric strength for the muscles of the lower limb, specifically in the plantarflexors.  The plantarflexors are important for carrying out functional activities and contribute to mobility and overall performance in older adults. Examining skeletal muscle quality and architecture may provide additional insight into factors influencing age-related changes in strength. Although age-related reductions in muscular strength have been well documented, we are aware of no previous studies that have simultaneously examined the neural and muscle specific factors contributing to the age-related reductions in rapid strength.

The purpose of this study was to determine specific mechanisms contributing to the age-related reduction in plantarflexion rapid strength at early (0–50 ms) and late (100–200 ms) time intervals of muscle contraction.

What did you do and what did you find in this study?

Thirty-two young and 20 older recreationally active men performed rapid plantarflexion isometric muscle actions to examine absolute and normalized rapid strength and muscle activation using electromyography at early and late time intervals. Ultrasonography was used to examine medial gastrocnemius muscle size, echo intensity for muscle quality, and muscle architecture [fascicle length and pennation angle].

We found that the older men were weaker, and had lower rapid strength in the later interval of muscle contraction in both absolute and normalized (adjusted to peak strength) terms when compared to the young men.

Gena1

Absolute torque at 50, 100, and 200 ms for the young and older men during rapid plantarflexion isometric contractions. *P<0.05, significant difference between the young and older men. Data are mean (SD).

The older men also had higher EI (poorer muscle quality), smaller pennation angles, and lower muscle activation in the later interval of contraction. However, we did not observe differences in rapid strength or muscle activation for the early interval of muscle contraction, or in muscle size, or fascicle length between groups. Interestingly, lower late interval rapid strength values were related to poorer muscle quality, smaller pennation angles, and lower muscle activation values; however late interval rapid strength values were no longer related to pennation angle after taking peak torque into account.

How do these findings impact the public?

side-profile-of-calfOur findings indicated that the lack of differences in the early interval of contraction may suggest that older men initially have similar muscle activation to younger men, but are unable to sustain the same rates of muscle activation during the late intervals of contraction. Furthermore, additional factors such as poor muscle quality and smaller pennation angles appear to also play a role in the age-associated changes of rapid strength. These findings add to our understanding of the importance of the various factors that influence the age-related reductions in rapid strength, which has been shown to significantly influence function and performance in older adults.

Metabolic Characterization of Overweight and Obese Adults

Research Team Members: Katie R. Hirsch, Abbie E. Smith-Ryan, Malia N.M. Blue, Meredith G. Mock, Eric T. Trexler, Kristin S. Ondrak

Why did you do this study?

Metabolic syndrome is a chronic disease characterized by the presence of multiple risk factors, including insulin resistance and poor cholesterol, which are associated with an increased risk for the development of cardiovascular disease, type-2 diabetes, and other metabolic diseases. The presence of excess body fat is highly associated with the development of metabolic syndrome, however, previous studies have identified a significant portion of overweight and obese individuals who have no risk factors and are considered metabolically healthy despite having a high percentage of body fat.

Picture3

Body composition scan using dual-energy x-ray absorptiometry

Despite an apparently normal metabolic status, excess body fat and difficulty achieving a healthy body composition may indicate the presence of underlying metabolic dysfunction overlooked by standard clinical tools. Currently, body mass index (BMI), cholesterol, and blood lipid levels serve as the primary screening tools for health risk.  However, the diagnostic value of these measures is limited by the inability to evaluate body composition (the differentiation between fat mass and lean mass) and fat distribution.  Regional distribution of body fat describes where an individual tends to store body fat.  Greater fat in the abdominal region and around the organs, known as visceral fat, is highly associated with insulin resistance in both overweight and normal weight individuals.  Visceral fat is also more highly associated with metabolic dysfunction than total body fat.  Lean mass (which includes muscle and organs) also has important associations with metabolic health.  Low relative lean mass is associated with insulin resistance, decreased metabolic rate, impaired fat metabolism, and poor functionality in activities of daily living, all of which are associated with weight gain and metabolic dysfunction.  Finally, hormonal imbalances, specifically related to insulin, leptin, estradiol, and cortisol, can lead to an unfavorable distribution of fat in the abdominal region, impair fat and glucose metabolism, and may also negatively impact energy expenditure.

 

Although traditional metabolic risk factors are highly associated with health risk, a more comprehensive evaluation of metabolic health may be a more appropriate and sensitive approach to evaluating metabolic status, regardless of body weight.   Evaluation of non-traditional metabolic factors, such as visceral fat, lean mass, resting metabolic rate, substrate utilization, and hormonal status, could provide valuable insight into aspects of metabolic health that may otherwise be overlooked. This in turn could improve the detection, prevention, and treatment of metabolic health issues. Therefore, the purpose of this study was to characterize metabolic health in overweight and obese adults using traditional and non-traditional metabolic variables.

What did you do and what did you find in this study?

Picture2

Resting metabolic rate test using a ventilated canopy and indirect calorimetry.

Body composition, visceral fat, resting metabolic rate, resting substrate utilization (use of carbs or fat for energy at rest), fasting cholesterol, blood lipids, glucose, and the hormones insulin, leptin, estradiol, and cortisol were measured in forty-nine overweight and obese men and women.  When evaluating traditional metabolic risk factors (blood glucose, triglycerides, and HDL cholesterol) 86.7% of the individuals had no more than one risk factor and 92% had no more than two risk factors, meaning this group could be considered metabolically healthy by traditional standards.  When evaluating visceral fat, in addition to traditional risk factors, the proportion of individuals considered to have metabolic dysfunction increased to 28.9%.  The occurrence rate increased to 80% when all metabolic risk factors were considered, classifying a majority of the group as metabolically dysfunctional. For men, the most common risk factors were high LDL cholesterol (82.6%), low metabolic rate (60.9%), low HDL cholesterol (47.8%), and high total cholesterol (43.5%).  For women, low HDL cholesterol (50.0%) and high LDL cholesterol (50.0%) were the most common risk factors, followed by low metabolic rate (30.8%), high visceral fat (19.2%), and greater reliance on carbohydrates for energy at rest (19.2%).

How do these findings impact the public?

 

Picture1

Ultrasound image of visceral fat thickness. Measurement was taken from the abdominal muscles to the aorta.

Results of this study show the importance of evaluating metabolic health beyond traditional diagnostic criteria. Evaluating components of body composition and metabolic function, such as visceral fat, lean mass, resting metabolic rate, and substrate utilization, in addition to hormonal and metabolic profiles, can give significant insights into metabolic status regardless of body weight and BMI status.  Knowledge of these factors could significantly improve lifestyle treatment approaches. Further, men and women exhibited different frequencies of risk factors, likely attributable to differences in fat distribution and hormonal status, reinforcing the importance of sex-specific evaluations. A unique aspect of this study was the use of ultrasound to measure visceral fat. Portable equipment, such as ultrasound, can improve the accuracy and evaluation of abdominal obesity-related risk, which is currently not evaluated in a clinical setting.  Additionally, connecting individuals with metabolic specialists who have access to more extensive assessment tools could lead to more effective intervention approaches.

 

 

 

Attenuation of Resting but Not Load-Mediated Protein Synthesis in Prostate Cancer Patients on Androgen Deprivation

Research Team Members: Erik Hanson, Andre Nelson, Daniel West, John Violet, Lannie O’Keefe, Stuart Phillips, Alan Hayes

These findings were recently published in Journal of Clinical Endocrinology and Metabolism, March 2017, 102(3): 1076-1083

Why did you do this study?

Prostate cancer is the most common non-dermatological form of cancer in US men (diagnosed in 1 in 7 men) and is the second leading cause of cancer-related death. In 2017 alone, it is estimated that 161,360 new cases of prostate cancer will be diagnosed with 26,730 deaths.

Androgen deprivation therapy (ADT) is a type of prostate cancer treatment that slows tumor growth but has several side effects, including the loss of muscle mass, strength, and physical function. All of these changes have a negative impact upon health-related quality of life. Exercise interventions have become more common to help reduce treatment-related side effects. Specifically, resistance training during ADT improves muscle strength, reduces fatigue, and enhances physical function. However, it is unclear as to whether or not significant gains in muscle mass are possible during ADT.

Looking at the recent literature, some studies have reported that no muscle hypertrophy occurs with resistance training during ADT. Others have shown that muscle gains are possible but the response is attenuated. Recently, our lab has demonstrated that high intensity resistance training induces gains in lean mass that are comparable to healthy, age-matched controls.

protein-powder-nutritional-supplementProtein supplementation is often used with resistance training to enhance the response. However, very few studies have combined these two muscle building strategies and used them during ADT as a means of preserving lean muscle mass and function and no studies have looked at the muscle protein synthesis response. Determining the acute response initially will provide important information for desiging future resistance exercise and dietary interventions, as it is repeated transient increases in muscle protein synthesis that may lead to increases in lean tissue over time.

Therefore, the purpose of this study was to determine the acute muscle protein response to whey protein supplementation with and without resistance exercise in men being treated for prostate cancer with ADT and healthy controls. We hypothesized that baseline protein synthesis would be suppressed with ADT but that diet- and exercise-induced increased in protein synthesis would be normal.

What did you do and what did you find in this study?

We measured muscle protein synthesis (MPS) from biopsy samples obtained from the thigh muscles at rest and 4h after participants consumed 40g of whey protein (Fed) and 40g of whey protein plus 3 sets of knee extension resistance exercise (Ex-Fed).

Muscle protein synthesis was lower during ADT at rest and while feeding (Fed) increased the rate of synthesis, the response was attenuated. However, the change in muscle protein synthesis from rest to Ex-Fed was similar to healthy controls.

hanson_fig1

* Significantly different from CON at the specific time point, P<0.01
† Significantly different from baseline value, P<0.001
‡ Significantly different from baseline and FED condition, P<0.001

How do these findings impact the public?

Muscle protein synthesis at rest is lower with ADT, which is likely why there is the loss of muscle mass in these patients. However, muscle protein synthesis increases following large doses of whey protein, although it is not as effective during ADT. But the combination of whey protein and vigorous resistance exercise may be an effective means to offset the side effects of prostate cancer treatment.

Future studies are needed to explore why protein synthesis is activated less with feedling alone, as this ‘anabolic resistance’ may have significant consequences for men on ADT. We are currently developing projects that will help to clarify these findings in the future.

Education Through Athletics – Possibilities for Intercollegiate Athletics Reform

This week’s EXSS Impact Post is developed by Professor Erianne Weight.

In a previous EXSS Impact blog post exploring reform approaches in intercollegiate athleticsweight1, we discussed the tension between athletics and the academy.  Many university stakeholders fully support athletics within the academy and view it as an educational endeavor complimentary to the university mission with added brand-building, relationship-forging, and student-drawing benefits.  On the other end of the spectrum, stakeholders have condemned the academy for allowing athlete exploitation, excessive commercialism, and unprincipled behavior that undermines the educational mission of the university.  Regardless of perspective, athletics has traditionally been supported within the university’s organizational structure as an extra-curricular activity peripherally related to the university mission. Perhaps it is time for this to change.

weight2Why did you do this study?

Throughout our research exploring the educational impact of intercollegiate athletics on the athlete participants, several studies have highlighted the positive impact intercollegiate athletics can have on occupational,[1] psychological,[2] physiological,[3] and long-term quality of life measures.[4] These findings contribute to a growing body of literature which supports embedding the applied study of athletics within the academy similar in form to music, dance, or theatre. Prior to exploring the interest or form of what an athletics-centric curriculum may entail, we gathered baseline data to examine current practices within NCAA Division I, II, and III institutions. The full results of this research are published in the Journal of Intercollegiate Sport.[5]

weight3What did you do and what did you find in this study?

Through survey of a stratified random sample of National Collegiate Athletics Association (NCAA) Division I, II, and III athletic academic advisors (n = 240), this exploratory study examined the prevalence, design, and institutional perceptions of classes offered exclusively for varsity athletes. Results indicate 33.9% of sample schools award credit for athletic participation (e.g. physical education), and 20.1% offer academic courses specifically for athletes (e.g. first semester “onboarding” courses, leadership courses, etc.).  Academic opportunities for athletes were greater in western, public, Division I institutions, with one of the most startling differences between western schools, wherein 65.3% award credit for participation, and southeastern schools, wherein 17.3% award credit for participation.

weight4How do these findings impact the public?

This study provides some evidence of structural and philosophical academic integration of athletics within the academy. These established courses counter the historically taboo nature of the education through athletics proposal.  This study also documents tremendous inequity in inter-institutional practices of facilitating academic courses for athletes.  This variance in institutional procedure can result in significant fluctuations in athlete time, competitive advantages, and opportunities for education through athletics.  Given the extensive policies the NCAA regulates to facilitate an even playing field, this dramatic divide in inter-institutional procedure presents an interesting challenge that warrants further inquiry.

weight5As the political-educational arena grapples with unprecedented scrutiny, faculties and administrators should focus their efforts on facilitating rich holistic educational opportunities and experiences. The athlete-educational experience that has been a concern since them inception of intercollegiate athletics has led many faculties to fear athlete-centric programming for reasons including an exacerbation of social isolation and/or the perceived nonacademic collective hubris and entitlement of athletes. Although there is a degree of isolation within every academic discipline with major-only courses and experiences that do not require justification, the unique nature of the athlete experience may necessitate additional consideration due to the social, commercial, and administrative pressures that could lead to academic clustering and athlete-segregation.

For this reason, a practical approach to athlete-centric educational experiences should be conscious of these realities and address concerns judiciously through credit limitations, cross-disciplinary faculty involvement, and the inclusion of non-athlete elite performers in the programming. Three approaches Weight & Huml (2016) recommend and expand upon in the Journal of Intercollegiate Sport article include:

  1. A 3-credit “onboarding” course specific for athletes to institutionalize many of the first-semester mandatory NCAA trainings in addition to life-skills initiatives
  2. Credit for participation in intercollegiate athletics with an infusion of faculty-led education grounded in experiential learning theory practices (e.g. a faculty-led strength training course with elements of exercise physiology and nutritional principles coupled with the strength training they engage in as a team).
  3. A minor in “elite performance” which could include varsity athletes, club sport athletes, musicians, orators, dancers, thespians, etc. Courses might include performance psychology, leadership and group dynamics, performance nutrition, media training, entrepreneurship, etc. in addition to two 3-credit “field experience opportunities that allow the students to reflect upon their elite experiences, apply literature to their (on-the-court) study, meet with a faculty and field supervisor (coach) to set and track learning goals, and infuse institutionalized scholarship and growth structures into their elite pursuits of excellence.

[1] Chalfin, P., Weight, E.A., Osborne, B., Johnson, S. (2015). The value of intercollegiate athletics participation from the perspective of employers who target athletes. Journal of Issues in Intercollegiate Athletics. 8, 1-27.

[2] Weight, E.A., Navarro, K., Huffman, L., Smith-Ryan, A. (2014). Quantifying the psychological benefits of intercollegiate athletics participation: Implications for higher education policy and practice. Journal of Issues in Intercollegiate Athletics. 7, 390-409.

[3] Weight, E.A., Navarro, K., Smith-Ryan, A., Huffman, L. (2016). Holistic Education through Athletics: Health literacy of intercollegiate athletes and traditional students. The Journal of Higher Education Athletics and Innovation. 1, 38-60.

[4] Weight, E.A., Bonfiglio, A.*, DeFreese, J.D., Kerr, Z., Osborne, B. In Review. Occupational Measures of Former NCAA Athletes and Traditional Students. The Journal of Intercollegiate Sport.

[5] Weight, E.A., Huml, M.* (2016). Facilitating education through athletics: An examination of academic courses designed for NCAA athletes. Journal of Intercollegiate Sport, 9(2), 154-174.

Fat-Free Mass Index in NCAA Division I and II Collegiate American Football Players

Research Team Members: Eric Trexler, Abbie Smith-Ryan, Malia Blue, Richard Schumacher, Jerry Mayhew, J. Bryan Mann, Pat Ivey, Katie Hirsch, Meredith Mock

Links to Study: https://www.ncbi.nlm.nih.gov/pubmed/27930454

uncfbWhy did you do this study?

It is well known that an athlete’s body composition can influence their athletic success. Previous studies have shown that fat-free mass (FFM) is related to strength, power, speed, and sport performance. However, fat-free mass may not be the most valid indicator of an athlete’s sport-related capabilities; most sports require locomotion or propulsion of the athlete’s body, which is affected by both the capacity to produce force and the overall size of the body. In addition, taller people naturally have more FFM due to their height. Fat-free mass index (FFMI) scales an individual’s FFM to their height, which removes the bias of height and may be a more valid characterization of muscularity that translates more directly to sport-related tasks.

In sports such as American football, training and nutrition practices are often geared towards increasing FFM. Researchers have previously suggested that 25 kg∙m-2 is the natural FFMI limit for resistance-trained males; this is important because identifying upper limits would enhance the ability to set realistic body composition goals for athletes. However, the research identifying this limit used a sample of lean individuals who were not competitive athletes. As such, it is possible that this “limit” has been underestimated. Collegiate football players are an ideal population for evaluating high FFMI values, based on the sport’s emphasis on strength, power, and body size. Furthermore, evaluating a large sample of collegiate football players allowed us to determine if FFMI differs between position groups or levels of competition. This information would be tremendously valuable to nutrition and strength & conditioning professionals who assist football players in identifying and reaching body composition goals that are suitable for their playing position.

GEHC-iDXA-for-Bone-Health_OverviewWhat did you do and what did you find in this study?

For this study, we performed dual-energy x-ray absorptiometry (DEXA) scans on three separate college football teams, including two division I teams and one division II team. We compared FFMI values between position groups and levels of play, and results indicated that FFMI was significantly higher in division I players compared to division II. Further, FFMI was drastically different between position groups, with the highest values observed in offensive and defensive linemen, and the lowest values observed in offensive and defensive backs. We provided FFMI ranges for each specific position based on the data from division I athletes, which should assist players in setting position-specific goals for body composition. Most importantly, we found that 62 athletes had FFMI values above 25 kg∙m-2 (26.4% of the sample). This percentage was even higher when specifically looking at division I athletes (31.3%). The 97.5th percentile was 28.1 kg∙m-2, and the highest observed value was 31.7 kg∙m-2.

How do these findings impact the public?

Our results indicate that drug-tested, resistance-trained males can achieve FFMI values well beyond 25 kg∙m-2. We also determined that FFMI effectively discriminates between playing levels and playing positions. Coaches and athletes can use this information to set more realistic body composition goals, and college and professional football teams may use this position-specific data to assist with their recruiting and personnel decisions.