Grant: Discovery Grants Program - Individual

Walking is a complex activity that requires the coordination of the upper and lower limbs while ensuring the control of the trunk. The long-term objective of this continuing program is to understand the fundamental processes involved in locomotion and to identify how the locomotor system adapts to the environment across the lifespan. Over the next 5 years, the short-term objectives of my research program are to 1. Determine the effect of optimized active arm motion on gait control strategies and gait stability, 2. Establish how motor variability in the upper limb contributes to gait control strategies and gait stability in (a)symmetric gait, 3. Evaluate the sensitivity of IMU-based joint angle to asymmetric gait conditions. Finally, we will determine how healthy aging and sex affect gait control strategies to regulate gait stability. The protocols will include healthy young (18-29 years) and older (55+ years) adults (N=50 per group) with an equal number of males/females. Gait trials will be performed using a dual-belt treadmill. In theme 1, we will 1a: Establish the effect of arm motion amplitude on interlimb coordination and gait performance. Walking at a comfortable pace on the treadmill a baseline trial will determine normal arm motion. Four active arm swing trials will be completed by adding 20% increments from baseline. This is necessary to determine the "optimal" active arm swing to be used in 1b., which will examine the effect of assisting active arm swing on adaptive strategies and gait stability. Trials will include normal, active unassisted, actively assisted, and passively assisted arm swings. Theme 2: to determine the impact of the upper limb motor variability on gait performance, participants will complete gait trials including normal arm swing/symmetric gait, normal arm swing/asymmetric gait, locked elbow/symmetric gait, and locked elbow/asymmetric gait. Finally, in theme 3, participants will be instrumented for both MOCAP and IMU-based gait assessments and walk on the dual-belt treadmill with 5 increments of gait (a)symmetry: normal gait and 5%, 10%, 15%, and 20% belt speed difference. We will evaluate model accuracy and consistency, and sensitivity to within-participant gait responses to asymmetry conditions as well as determine the effect of age and sex. Gait profiles will be analyzed using traditional (e.g., meanSD), nonlinear approaches (e.g., ?max) and modern analytical techniques (Statistical Parametric Mapping, concatenated non-negative factorization) to determine age and sex-specific gait adaptive neuromuscular strategies. This program is necessary to understand the processes occurring when walking in challenging environments and to provide insights into sex and age-specific gait control strategies. This is critical to the development of comprehensive biomechanical models to assess human motion and gait dynamic stability and reduce/prevent the occurrence of falls in individuals of different ages and sex.