Acute Effects of Contraction Speed during Motor Imagery on Corticospinal and Muscle Function Responses
Disciplines
Exercise Science | Motor Control
Abstract (300 words maximum)
BACKGROUND: Motor Imagery (MI) is the imagination of a movement without physical muscle contraction. Acute MI has been shown to increase strength and corticospinal excitability, but few studies have placed emphasis on the rate of torque development (RTD) during MI or as an outcome following MI. RTD refers to how quickly skeletal muscle generates torque and is associated with mobility in aging and clinical populations. MI has implications for these populations where traditional strength training is not possible, so it is important to determine its effect on RTD. Corticospinal responses to MI are muscle and task specific, but it is unclear if the speed of imagined muscle contractions affects neural responses. This study aims to determine the acute effects of fast and slow imagined contractions on corticospinal responses and RTD. METHODS: Eighteen young (18-30 yrs), healthy subjects will complete 4 laboratory visits in randomized order, including a familiarization session, control, and 2 MI conditions. During MI conditions, subjects will imagine 2 sets of 25 repetitions of either fast (i.e., increase torque as fast as possible) or slow (i.e., 3 seconds to peak torque) isometric elbow flexions. Before and after each condition, single pulses will be delivered over the primary motor cortex using transcranial magnetic stimulation to measure motor-evoked potential amplitude and the resulting silent period duration for the bicep brachii to quantify changes in corticospinal excitability and inhibition, respectively. Rapid, maximal voluntary isometric contractions will be used to measure changes in peak torque, RTD, and rate of electromyography rise. Two-way repeated measures ANOVAs will be used to analyze outcomes. ANTICIPATED RESULTS: Compared to control, we expect both MI conditions to acutely increase corticospinal excitability, peak torque, and RTD while reducing corticospinal inhibition, but we expect greater changes in these outcomes following fast MI.
Academic department under which the project should be listed
WCHHS - Exercise Science and Sport Management
Primary Investigator (PI) Name
Garrett Hester
Acute Effects of Contraction Speed during Motor Imagery on Corticospinal and Muscle Function Responses
BACKGROUND: Motor Imagery (MI) is the imagination of a movement without physical muscle contraction. Acute MI has been shown to increase strength and corticospinal excitability, but few studies have placed emphasis on the rate of torque development (RTD) during MI or as an outcome following MI. RTD refers to how quickly skeletal muscle generates torque and is associated with mobility in aging and clinical populations. MI has implications for these populations where traditional strength training is not possible, so it is important to determine its effect on RTD. Corticospinal responses to MI are muscle and task specific, but it is unclear if the speed of imagined muscle contractions affects neural responses. This study aims to determine the acute effects of fast and slow imagined contractions on corticospinal responses and RTD. METHODS: Eighteen young (18-30 yrs), healthy subjects will complete 4 laboratory visits in randomized order, including a familiarization session, control, and 2 MI conditions. During MI conditions, subjects will imagine 2 sets of 25 repetitions of either fast (i.e., increase torque as fast as possible) or slow (i.e., 3 seconds to peak torque) isometric elbow flexions. Before and after each condition, single pulses will be delivered over the primary motor cortex using transcranial magnetic stimulation to measure motor-evoked potential amplitude and the resulting silent period duration for the bicep brachii to quantify changes in corticospinal excitability and inhibition, respectively. Rapid, maximal voluntary isometric contractions will be used to measure changes in peak torque, RTD, and rate of electromyography rise. Two-way repeated measures ANOVAs will be used to analyze outcomes. ANTICIPATED RESULTS: Compared to control, we expect both MI conditions to acutely increase corticospinal excitability, peak torque, and RTD while reducing corticospinal inhibition, but we expect greater changes in these outcomes following fast MI.