Date of Award

8-2022

Document Type

Thesis

Degree Name

Master of Science in Biology

Department

Biology

First Reader/Committee Chair

Angela Horner

Abstract

Tendons connect and transmit energy between muscles and bones and play a key role in movement. Tendon remodels by breaking down and absorbing tendon components including collagen fibers and elastin while replacing them with newly formed tendon. These processes can be influenced by short- and long-term factors such as exercise and aging; the magnitude of influence on tendon remodeling remains unclear. I researched the effects of maturation and exercise on tendon remodeling using a mice colony artificially selected for high voluntary wheel running called high-runner mice. Control and high-runner linetype mice were separated into 2 age cohorts that started training at 3- and 9-weeks of age, which correspond to before and after skeletal maturity. Each cohort was divided into 3 training groups that vary in exercise intensity: wheel running (high-frequency, low-impact), jumping (low-frequency, high-impact), and a sedentary group. After 9 weeks of training, gastrocnemii tendons were harvested. I measured gross tendon morphology and applied materials testing for measuring mechanical properties. The results show minimal significant differences between tendon mechanics suggesting that training intensity does not have a significant impact during maturation; however, linetype had a significant effect on tendon length, which is suggestive of cursorial evolution. Cursorial animals have evolved longer, thinner tendons capable of storing more elastic strain energy for more efficient locomotor behaviors, but it remains questionable if this is the case for high-runner mice. Future studies should investigate whether early-life exercise impacts lifelong mechanical properties measurable in advanced-aged tendon. These studies should be paired with histological methods to quantify concurrent changes in tendon composition.

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