Life Sciences Commons^™

The Effect Of Postural Perturbations On Cardiovascular And Skeletal Muscle Function In Healthy Adults, Patrick Siedlecki

Electronic Thesis and Dissertation Repository

Maintenance of standing balance is vital to daily living. Traditionally, perspectives on maintaining balance are achieved through the study of visual, vestibular and somatosensory inputs on motor outputs. While evidence suggests cardiovascular regulation also functions to assist postural control during orthostatic stress, how the cardiovascular system responds to postural perturbations is not well established. This dissertation includes four studies that investigated the effects of postural perturbations on the cardiovascular system and skeletal muscle responses in healthy adults. All of the studies involved exposing standing participants to surface-translation perturbations at different velocities, with known or unknown timing, and occurred while spontaneously …

The Effect Of A Combined Multiple-Modality Exercise Intervention On Sensorimotor Function In Community Dwelling Older Adults, With A Subjective Cognitive Complaint: The M4 Study (Multi-Modal; Mind Motor), Sam Titheridge

Electronic Thesis and Dissertation Repository

Aging is associated with the increased onset of diseases such as cognitive impairment, and ultimately dementia. Participants, 55+ years, with a self-reported cognitive complaint completed a 6-month exercise intervention. They were randomized to either a multiple modality exercise program (M2), consisting of aerobic, stretching and balancing exercises or a multiple modality plus mind motor program (M4), whereby a square stepping exercise was incorporated. Participants were assessed for reaction time (RT), movement time (MT) and % errors at baseline and at 6-months using an eye tracking 1000 system. Participants performed prosaccades and antisaccades (AS). AS RT was significantly quicker from baseline …

The Effects Of A Multiple-Modality Mind-Motor Program On Vascular Outcomes In Community-Dwelling Older Adults With Subjective Cognitive Complaints, Amanda M. Deosaran

Electronic Thesis and Dissertation Repository

Studies have found a link between cardiovascular risk factors (CVRFs) and Alzheimer’s disease however; the mechanism by which CVRFs increase the risk of cognitive decline is not fully understood. The current study attempts to improve CVRFs in order to enhance cognition in older adults. Primary outcomes include ambulatory and clinical resting systolic and diastolic blood pressure (SBP; DBP). In total, 89 community-dwelling older adults with subjective cognitive complaints were randomized to either a multiple-modality mind-motor (M4) exercise or a multiple-modality (M2) exercise only. Significance was found in nighttime peak SBP (6.55 mmHg, p=.04) between groups, with a decrease in M2 …

Decreased Peak Muscle Power Is Associated With Motor Unit Loss In The Lower Limb Of Older Adults, Neal B. Mckinnon

Electronic Thesis and Dissertation Repository

This study investigated the relationship between motor unit (MU) properties and the strength and power of two lower limb muscles in healthy young and old adults. Twelve older adults (mean age, 77 ± 5 yrs) and twelve young adults (mean age, 24 ± 3 yrs) were studied. MU properties of the tibialis anterior (TA) and vastus medialis (VM) muscles were determined using decomposition-enhanced spike-triggered averaging (DE-STA). Motor unit number estimates (MUNE) of the TA were significantly reduced (p>0.05) in older adults (102 ± 76) compared to young adults (234 ± 109), primarily as a result of significantly larger surface-detected …

Quantifying The Effect Of Age And Contraction Mode On The Force-Velocity-Power Relationship In The Knee Extensors, Justin R. Paturel

Electronic Thesis and Dissertation Repository

PURPOSE: To assess and compare the force-velocity-power relationship (F-V-P) using isotonic and isokinetic knee extensions in 11 younger (19-30y) and 11 older (69-81y) men. METHODS: The construction of the F-V-P curves were attained with each participant performing maximal, explosive knee extensions at 8 different loads (isotonic) and 8 different velocities (isokinetic) on a Cybex HUMAC NORM dynamometer. Maximal voluntary contraction (MVC or P_o), maximal shortening velocity (V_max), maximum power, optimal torque (P_opt) and velocity (V_opt) were assessed and compared. RESULTS: The older men were 43% weaker, 18% slower and ~54% less powerful …

The Effects Of Age And Long-Term Endurance Training On Vo2 Kinetics, Tyler M. Grey

Electronic Thesis and Dissertation Repository

The kinetics of the adjustment of pulmonary oxygen uptake (VO₂) was examined during step transitions from 20 W to moderate-intensity cycling in young (Y), middle-aged (M), and older (O) endurance trained and untrained men. VO_2p was measured breath-by-breath and changes in deoxygenated hemoglobin ([HHb]) were measured by near-infrared spectroscopy. VO_2p and [HHb] were modeled with a monoexponential model. The kinetic time constant for VO₂ (τVO_2p) was not different across age-groups (P > 0.05) in the trained group (17 ± 8, 18 ± 5, and 20 ± 5 s, in Y, M, and O, respectively). …

Electromechanical Delay Of The Dorsiflexors In Young And Old Women, In H. Choi

Electronic Thesis and Dissertation Repository

PURPOSE: The aim of the current study was to examine the effect on electromechanical delay (EMD) in the dorsiflexors of young and old women during maximal isometric voluntary and electrically evoked contractions, and after a bout of lengthening contractions. METHODS: Nine young (25.1±1.3 years) and nine old (68.3±6.1 years) women performed baseline isometric contractions with evoked twitches followed by a series of dynamic lengthening contractions using a Biodex multi-joint dynamometer. Maximal isometric voluntary and evoked contractions were measured to assess EMD. Time points were recorded at baseline, mid-point of the intervention, post-task termination, and during recovery at 0.5, 2, 10, …

Neuromuscular Function Following Lengthening Contractions, Geoffrey A. Power

Electronic Thesis and Dissertation Repository

Unaccustomed lengthening contractions have been shown to impair muscle function - however little is known regarding this impairment on muscle power - specifically, the velocity component of power during voluntary contractions in humans. The four studies presented in my thesis investigated power-loss following lengthening contractions in healthy young and old women and young men.

The purpose of Study 1 was to determine reliability of velocity-dependent power of the dorsiflexors using the isotonic mode of the Biodex Dynamometer. I determined the isotonic mode is reliable and can be used to track changes in velocity and power following fatigue and lengthening contractions. …

Neuroprotective Effects Of Long-Term Endurance Training On The Cortical Autonomic Network In The Aging Brain, Torri A. Luchyshyn

Electronic Thesis and Dissertation Repository

This study tested whether long-term endurance training in older adults (ET; n = 15, 55 ± 4 years, relative VO₂max = 50 ± 8 ml/kg/min) would alter cardiovagal control and preserve the cortical autonomic network compared to age-matched controls (CON; n = 15, 56 ± 4 years, relative VO₂max = 37 ± 9 ml/kg/min). The hypothesis predicts 1) altered deactivation patterns of the ventral medial prefrontal cortex (vMPFC) in response to isometric hand grip (IHG) and 2) greater indices of cardiovagal control; a) increased baroreflex sensitivity at rest, b) greater heart rate change (ΔHR) and c) …