Regulation of skeletal muscle strength adaptations by dietary protein and resistance training in middle adulthood

Skeletal muscle aging is associated with decreased muscle mass and strength. These factors are a significant contributor to not only physical independence but also chronic disease severity and even mortality. Aging-associated muscle pathology is complex, but it is partly due to dysregulated protein synthesis and oxidative status. Given the complexity of muscle dysfunction with advancing age, it may be prudent to explore lifestyle strategies and therapeutic targets that impact a variety of aging-associated pathologies to effectively maintain muscle quality. Middle adulthood is a key life stage to implement these strategies as a preventative measure to maximize the healthspan. The scientific consensus for dietary protein needs to support resistance training (1.6 g·kg-1·d-1) extrapolate total dietary needs from supplementation studies, disregarding the role of protein timing and quality. Accordingly, more thorough dietary control is required to address this question appropriately. Likewise, molecular therapeutic targets known to interact with both protein synthesis and redox pathways in preclinical models have not been corroborated in humans. The purpose of the studies in this dissertation was to examine how dietary protein and resistance training contribute to healthy aging from the perspective of skeletal muscle. This objective was achieved through a dietary counseling-controlled resistance training intervention in middle-aged adults assessing strength, lean mass, cardiometabolic biomarkers, and skeletal muscle tissue at baseline and after the 10-week intervention. In study I, we demonstrated that a high protein diet (~1.68 g·kg-1·d-1) does not potentiate resistance training-induced strength and lean mass gains in comparison to a moderate protein diet (~1.16 g·kg-1·d-1) in middle-aged adults. Furthermore, diets rich in high-quality animal protein foods were shown to not affect cardiometabolic disease risk when consumed during a resistance training program. In study II, we showed that resistance training increased molecular mediators of hypertrophy and oxidative function as well as mitochondrial respiratory capacity, which corresponded to strength gains. The studies in this dissertation demonstrated that the strategic consumption (e.g., high-quality sources during anabolic feeding windows) of moderate amounts of protein is sufficient to maximize strength and lean mass gains with resistance training. Moreover, strength adaptations with resistance training correspond to molecular mediators of healthy skeletal muscle aging.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Nutritional Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• McKenna, Colleen F.

Contributors dc:contributor

• Burd, Nicholas A
• Khan, Naiman A
• Boppart, Marni D
• Dilger, Anna C

• aging
• exercise training
• diet quality

Statement dc:rights

• Copyright 2022 Colleen F. McKenna

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115708

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115708