Interdisciplinary Research to Improve Body Composition

Lean muscle mass is an important determinant to a person’s overall health and functional ability, but as people age, their lean muscle mass declines. This age-related reduction, known as sarcopenia, can have negative health implications in a variety of areas, including resting metabolic rates and an individual’s ability to fight chronic metabolic diseases.

LesLee Funderburk, Ph.D., assistant professor in human sciences and design, is driving understanding of appropriate approaches to counter sarcopenia through interdisciplinary research. In a study published in Journal of the American College of Nutrition, Funderburk and collaborators published insights into lean muscle mass interventions for women between the ages of 40-65.

“In midlife, people’s bodies begin to decline in strength and lean mass unless they are purposefully doing something to prevent that,” Funderburk says. “We wanted to focus on women because women tend to have less muscle mass to start with and wanted to determine what simple interventions might be of benefit in maintaining the muscle mass they do have.”

Collaborative Research

Funderburk, who spent 26 years as an active duty U.S. Army officer, serving as a dietitian in the Army before coming to Baylor, joined the faculty of Baylor’s Robbins College of Health and Human Sciences in 2016. In addition to serving as an assistant professor and program director for Baylor’s Dietetic Internship program, she quickly immersed herself in collaborative research with faculty across campus.

The Robbins College was formed in 2014 to bring together a variety of departments that focus on health, human behavior and quality of life. Under the umbrella of a single college within Baylor, their partnership advances the Baylor mission in an interdisciplinary environment for discovery, research and service. From her own department, now known as Human Sciences and Design, Funderburk has partnered with researchers in a variety of departments, including Health, Human Performance and Recreation.

“I’m interested, of course, in researching quality nutritional intake, but I’m also interested in how we can maintain or improve body composition over time, with or without supplementation,” Funderburk says. “As a nutrition professional, the Robbins College affords me the opportunity to work with professors in exercise physiology, and incorporate students in that research. We have fantastic exercise physiology faculty, which is the perfect combination for a nutrition scientist as we evaluate the variety of ways people respond to interventions.”

Resistance Training and Leucine Supplements

Funderburk’s study with midlife-aged women provides a meaningful example of collaborative, health-centered research. Funderburk partnered with Darryn Willoughby, Ph.D., professor emeritus of health, human performance and recreation, to study the impact of resistance training, combined with supplemental leucine (amino acid), to counter lean muscle mass loss. Research has shown that muscle mass in midlife can decrease by as much as one percent each year. That seemingly small annual reduction can lead to a decline of 30 to 50 percent by the time a person reaches 80, necessitating meaningful interventions to improve health outcomes impacted by lean muscle mass.

Women participating in the 10-week study took leucine supplements while participating in a resistance training regimen designed to build lean muscle mass. Women participating in the 12-week study took leucine supplements and engaged in a resistance training regimen. Leucine is one of nine essential amino acids, and is known to be a trigger for muscle protein synthesis that can be protective of lean muscle mass, especially when an individual is receiving the right amounts of calories and protein..

The results, published in Journal of the American College of Nutrition, were clear. Whether previously trained in resistance training or having no experience with that form of activity, everyone who participated benefitted.

“We found that everyone in the study increased in strength and lean mass,” Funderburk says. “We didn’t really, however, see a difference in the leucine group versus the placebo group. The bottom line is, we saw women respond, pretty dramatically to resistance training. For postmenopausal women, it reversed the trend for lean mass loss.”

The results affirmed the benefits of resistance training while opening further lines of study. Many of the women who participated later indicated they wanted to lose weight, which was not an objective of the project. A follow-up study focused on the impact of leucine on lean muscle mass when a person is actively attempting to lose weight.

“When we lose weight purposefully, we tend to lose both fat and muscle—losing muscle is not a good thing,” Funderburk says. “In this case, we studied women for 12 weeks, and measured their caloric and protein intake, leucine dosage and more.”

In the second study, the women who were on the leucine supplement while working towards purposeful weight loss had greater odds of retaining lean muscle mass, and in some cases even gained lean mass, versus those in the placebo group.

Engaged Learning Through Research Experience

Students play an important role in Funderburk’s research. Undergraduate, graduate and doctoral students gain practical training and engaged learning opportunities as they participate in projects with Funderburk and her colleagues to evaluate a variety of health challenges.

“The students I am able to work with are truly interested in learning about nutrition and teaching people to be healthy,” Funderburk says. “Many of them have seen a family member struggle with health challenges, which has heightened their awareness of how healthy eating and healthy lifestyles can help prevent issues like heart disease, diabetes, or a stroke.”

“Our research focus in Robbins College, and Baylor with its focus on Tier 1 research, brings them on a pathway through the research process. It gives younger students hands-on experience in data collection, supplement preparation, preparing subject folders and more, and provides doctoral students with the chance to serve as research assistants who write protocols, collect data and help write collaboratively with the team. At every level, these projects help them experience what a research project is supposed to look like from start to finish as they work towards making a meaningful difference in people’s health.”