Must Older Muscles Be Weaker Muscles?

A former D1 football player seeks the answer — and his doctorate.

By Jennifer Anderson

As a tight end for the University of Wyoming Cowboys, Christopher Sundberg was already playing at a Division I level, but the question of how he could become a better football player still consumed him. “My passion for biomedical research originated in that initial desire to improve my performance on the field,” says Sundberg. “We know exercise is one of the best things we can do for ourselves, but we don’t really understand why.”

Sundberg is set to earn his doctorate in clinical and translational rehabilitation health sciences later this spring, and he is spending his remaining months studying the mechanisms of neuromuscular fatigue in health, disease and aging. As a recipient of a National Research Service Award from the National Institutes of Health, he’s able to focus exclusively on his goal of identifying how age-related loss of muscle mass and increased fatigability result in a reduced ability to perform everyday activities, a loss of balance and a decreased quality of life for the elderly.

“Something seems to happen to people around the age of 70; they lose muscle mass and fatigue much more rapidly than before,” explains Sundberg. “I want to understand why that is and how to prevent it.”

His hypothesis is that older-adult muscles are less efficient and more sensitive than young-adult muscles to the depressive effects of fatiguing metabolites that collect in the fibers. The accumulation of these metabolites makes the dynamic muscle contractions necessary for everyday living more difficult. Sundberg is testing this theory in two ways: first, by studying fatigue at the level of the single muscle fiber through muscle biopsies, and second by using magnetic stimulation to measure whether the amount and origin of fatigue differs with age or gender during dynamic muscle contractions.

Sundberg’s research benefits from the rare opportunity to work with two professors from different disciplines: Dr. Sandra Hunter, professor of exercise science, and Dr. Robert Fitts, professor emeritus of biological sciences. Examining cellular muscle biology with Fitts and neuromuscular physiology with Hunter, Sundberg is able to employ a translational approach of studying fatigue at both the single fiber level and within the entire neuromuscular system. He is optimistic that these studies will eventually translate into the design and testing of novel exercise interventions for adults as they age.

“Marquette is the ideal location for my training,” explains Sundberg. “It provides the rare opportunity to be trained concurrently in techniques at the forefront of the fields of cellular muscle biology and whole-body neuromuscular physiology.”

This story is part of a three-part series on grad student research at Marquette University. Read more here.

Adapted from Marquette’s 2018 Discover Magazine.
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