Energetics and coordination of skilled movement

Summary

Skilled people are more energetically efficient than unskilled people, yet little is known about how they achieve greater efficiency because the study of movement focuses on performance outcomes (task success, accuracy, error) and entirely neglects the metabolic energy cost.

Supervisor(s)

Associate Professor Nicholas O'Dwyer

Research Location

Exercise, Health and Performance Faculty Research Group, Faculty of Health Sciences

Program Type

N/A

Synopsis

This project is part of program of research on whole body coordination in infants, young adults, the healthy elderly and stroke patients. All movement is executed through the contraction of muscles and incurs the expenditure of metabolic energy. Skilled people are more efficient than unskilled people, so their energy cost for a given action is lower. Yet little is known about how people achieve greater efficiency with practice because traditional approaches to the study of movement focus on performance accuracy and neglect the energy cost. This project will redress this neglect by bringing the methodologies and expertise of three scientific disciplines – motor control and learning, exercise physiology, biomechanics – together, for the first time, to investigate the precise mechanisms (psychological, physiological, biomechanical) whereby people become more efficient as their movement skill increases with practice at a task. The project will be carried out in three complementary phases that will provide the most comprehensive account yet attempted of the multi-faceted nature of change in movement with increased skill.

• Phase 1) Learning of inter-limb coordination tasks (arm and leg cycling). Changes in movement skill will be quantified via kinematic, kinetic, energetic, EMG, attentional and sense of effort measures.
• Phase 2) Measurement of local muscle metabolic strain using phosphorus magnetic resonance spectroscopy (31P-MRS). Participants will reproduce in the MR scanner their duty cycles of muscle activation as recorded before and after practice of inter-limb cycling, so that we can measure how the metabolic energy costs change.
• Phase 3) Biomechanical modelling. Modelling the inter-limb cycling activities will provide the biomechanical mechanism of the movements, via a quantitative description of limb segment positions, orientations, joint moments and power outputs

Additional Information

Techniques used in the project:

• Phase 1: Simultaneous measurement will be made of six categories of variables (kinematic, kinetic, whole body energetic cost, muscle activity, attentional load and subjective sense of effort) before and after training. Testing of muscle stretch reflexes and limb mechanics (stiffness, damping, resonant frequency) will be carried out via a servomotor controlled manipulandum.
• Phase 2: Phosphorus magnetic resonance spectroscopy is a novel, specialised application of magnetic resonance which permits non-invasive real-time measurement of skeletal muscle metabolism in vivo. The technique can assess cellular bioenergetics and metabolic strain, thereby reflecting the energy cost and cellular disturbance of muscle contraction. There are only two laboratories using this technique in Australia and only a few worldwide with the capacity to undertake these measurements.
• Phase 3: Biomechanical modelling. While the muscle activity recorded in the inter-limb cycling studies will show which muscles are active and how their activity changes with skill learning, biomechanical models are required in order to understand precisely what the muscles do in each individual.

Possible research areas for PhDs topics: There are opportunities for PhD projects in each phase of the project.

Keywords

posture, muscle tone, motor function, disorders of movement, spasticity, hyperreflexia, hypertonia, Motor control, skill, coordination, muscle oxidative metabolism, phosphocreatine, mechanical energy expenditure, Biomechanics, stretch reflexes, Movement disorders, Human body, Movement

Opportunity ID

The opportunity ID for this research opportunity is: 100