Developmental Plasticity of Locomotion: Energetics, Mechanics, and Muscle
Open Access
- Author:
- Katugam-Dechene, Kavya
- Graduate Program:
- Kinesiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 18, 2023
- Committee Members:
- Jonathan Bates Dingwell, Professor in Charge/Director of Graduate Studies
Gustavo Nader, Outside Field Member
Stephen Piazza, Major Field Member
Meghan Vidt, Outside Unit Member
Jonas Rubenson, Chair & Dissertation Advisor - Keywords:
- Biomechanics
Energetics
Mechanics
Muscle
Developmental Plasticity
Locomotion
Kinematics
Comparative Biomechanics
Musculoskeletal Biomechanics
Muscle Mechanics - Abstract:
- In light of increasing trends of inactivity in children, it is important to understand how the musculoskeletal system adapts to varying levels of exercise during growth, and how these adaptations affect musculoskeletal health after maturation. Because of the practical and ethical limitations of controlled, long-term intervention studies in growing children, this dissertation used a bipedal animal model, guinea fowl (Numida meleagris) to address questions into developmental locomotor and musculoskeletal plasticity. The overarching questions addressed in this dissertation are whether an increased mechanical load stimulus during growth elicits musculoskeletal and locomotor adaptations that improve locomotor function, and whether these adaptations persist into adulthood. Guinea fowl were either fitted with a unilateral distal limb mass across the duration of maturation (load group; n = 20) or grown without external loading (control group; n = 20). The first study used measurements of metabolic energy consumption during treadmill walking, showing that locomotor economy responds plastically to increased mechanical load during growth, resulting in a markedly improved economy of limb load carriage. The second study assessed the retention of developmental adaptations, and found that animals converged back to ‘normal’ energetic abilities later in adulthood, even after their drastically different growth-period load stimulus. The third study investigated whether the improvements in locomotor economy discovered in Study 1 could be explained by adaptations in lower limb swing-phase joint mechanics. This study showed that the mechanical power required to swing the limb and move the added limb load could not explain the reduction in metabolic energy observed after chronic limb loading. The final study investigated whether the improved locomotor economy observed in Study 1 arose through adaptations in muscular architecture. A hybrid modeling-experimental approach revealed that chronic developmental loading resulted in both increased muscle mass and architectural adaptations that can improve muscle efficiency. Animals, however, exhibited multiple adaptive strategies, indicating that muscle architecture is not highly constrained in developing guinea fowl. Together, the findings of this dissertation indicate that the musculoskeletal system is highly plastic during development. Given the link between the effort required to move and engagement in exercise, these data indicate that growth-period exercise (or lack thereof) can affect the musculoskeletal system in ways that may impact the propensity for physical activity.