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Full-Text Articles in Physiology

A Comparison Of Commonly Used Accelerometer Based Activity Monitors In Controlled And Free-Living Environment, Yuri Feito Dec 2010

A Comparison Of Commonly Used Accelerometer Based Activity Monitors In Controlled And Free-Living Environment, Yuri Feito

Doctoral Dissertations

This dissertation was designed to determine the effects of body mass index (BMI) and walking speed on activity monitor outputs. A secondary purpose was to compare the activity monitors’ performance in a free-living environment. In the first experiment, 71 participants wore three waist-mounted activity monitors (Actical, ActiGraph, and NL-2000) and an ankle-mounted device (StepWatch 3) while walking on a treadmill (40, 67 and 94 m/min). The tilt angle of each device was measured. The Actical recorded 26% higher activity counts (P < 0.01) in obese persons with a tilt <10 degrees, compared to normal weight persons. The ActiGraph was unaffected by BMI or tilt angle. In the second experiment, the steps recorded by the devices were compared to actual steps. Speed had the greatest influence on the accuracy these devices. At 40 m/min, the ActiGraph was the least accurate device for normal weight (38%), overweight (46%) and obese (48%) individuals. The Actical, NL-2000 and StepWatch averaged 65%, 73% and 99% of steps taken, respectively. Lastly, several generations of the ActiGraph (7164, GT1M, and GT3X), and other research grade activity monitors (Actical; ActivPAL; and Digi-Walker) were compared to a criterion measure of steps. Fifty-six participants performed treadmill walking (40, 54, 67, 80 and 94 m/min) and wore the devices for 24-hours under free-living conditions. BMI did not affect step count accuracy during treadmill walking. The StepWatch, PAL, and the AG7164 were the most accurate across all speeds; the other devices were only accurate at the faster speeds. In the free-living environment, all devices recorded about 75% of StepWatch-determined steps, except the AG7164 (99%). Based on these findings, we conclude that BMI does not affect the output of these activity monitors. However, waist-borne activity monitors are highly susceptible to under-counting steps at walking speeds below 67 m/min, or stepping rates below 100 steps/min. An activity monitor worn on the ankle is less susceptible to these speed effects and provides the greatest accuracy for step counting.


Elucidating Functional Roles For Myogenin In Adult Skeletal Muscle Metabolism, Exercise Capacity, And Regeneration, Jesse Flynn Dec 2010

Elucidating Functional Roles For Myogenin In Adult Skeletal Muscle Metabolism, Exercise Capacity, And Regeneration, Jesse Flynn

Dissertations & Theses (Open Access)

The four basic helix-loop-helix myogenic transcription factors, myogenin, Myf5, MRF4, and MyoD are critical for embryonic skeletal muscle development. Myogenin is necessary for the terminal differentiation of myoblasts into myofibers during embryogenesis, but little is known about the roles played by myogenin in adult skeletal muscle function and metabolism. Furthermore, while metabolism is a well-studied physiological process, how it is regulated at the transcriptional level remains poorly understood. In this study, my aim was to determine the function of myogenin in adult skeletal muscle metabolism, exercise capacity, and regeneration. To investigate this, I utilized a mouse strain harboring the Myogflox …


Accuracy Of Physical Activity Monitors In Pregnant Women, Christopher P. Connolly May 2010

Accuracy Of Physical Activity Monitors In Pregnant Women, Christopher P. Connolly

Masters Theses

Purpose: To determine the step count accuracy of three pedometers and one accelerometer in pregnant women during treadmill walking. Methods: Subjects were 30 women in the second or third trimester (20-36 weeks) who were screened for pregnancy-related risk factors. Each subject was fitted with a belt containing three physical activity monitors: Yamax Digiwalker SW-200 (DW), New Lifestyles NL 2000 (NL), and GT3X Actigraph accelerometer (ACT). The Omron HJ-720 (HJ) was placed in the pants pocket. Subjects walked at 54, 67, 80, and 94 m•min-1 for two minutes each. Actual steps were determined by an investigator using a hand-tally counter. Percentage …


Myogenin Modulates Exercise Endurance By Altering Skeletal Muscle Metabolism, James Eric Meadows May 2010

Myogenin Modulates Exercise Endurance By Altering Skeletal Muscle Metabolism, James Eric Meadows

Dissertations & Theses (Open Access)

The function of myogenic regulatory factors (MRFs) during adult life is not well understood. The requirement of one of these MRFs, myogenin (Myog), during embryonic muscle development suggests an equally important role in adult muscle. In this study, we have determined the function of myogenin during adult life using a conditional allele of Myog. In contrast to embryonic development, myogenin is not required for adult viability, and Myog-deleted mice exhibited no remarkable phenotypic changes during sedentary life. Remarkably, sedentary Myog-deleted mice demonstrated enhanced exercise endurance during involuntary treadmill running. Altered blood glucose and lactate levels in sedentary Myog-deleted mice after …


The Effects Of Two Different Fatigue Protocols On Lower Extremity Kinematics And Kinetics During An Unanticipated Running Stop-Jump, David L. Quammen Apr 2010

The Effects Of Two Different Fatigue Protocols On Lower Extremity Kinematics And Kinetics During An Unanticipated Running Stop-Jump, David L. Quammen

Human Movement Studies & Special Education Theses & Dissertations

Altered neuromuscular control strategies and biomechanical movement risk factors are most likely to contribute to the increased incidence of non-contact ACL injury for female athletes. Neuromuscular control strategies and movement patterns are further altered when the effects of fatigue are present. The purpose of this study was to determine neuromechanical differences between two fatigue protocols [Slow Linear Oxidative Fatigue Protocol (SLO-FP) and Functional Agility Short-Term Fatigue Protocol (FASTFP)] when performing a running stop-jump task (RS). A sample of convenience of fifteen Division I female soccer players (age= 19.2 ± 0.8 years; height= 1.67 ± 0.05 m; mass= 61.7 ± 8.1 …


The Correlation Between Visual Observations And Inclinometric Measurements For Special Tests Related To Patellofemoral Pain Syndrome, Erin Quada Apr 2010

The Correlation Between Visual Observations And Inclinometric Measurements For Special Tests Related To Patellofemoral Pain Syndrome, Erin Quada

Human Movement Studies & Special Education Theses & Dissertations

Patellofemoral pain syndrome (PFPS) is generally described as an insidious onset with pain increasing during running, jumping, ascending and descending stairs as well as sitting with the knees flexed for an extended period of time. Clinicians often use special tests in injury evaluations and range of motion assessments, usually making a visual observation of that status of the patient. The purpose of this study was to examine how interval measurements utilized in flexibility and range of motion assessments correlate with visual observations of special tests (active knee extension test, Thomas test, Ober's test, rectus femoris flexibility, and Craig's test). The …


The Effects Of Two Types Of Fatigue On An Unanticipated Side-Step Cutting Task As Measured By Kinematic And Kinetic Variables, Shawn E. Lucci Apr 2010

The Effects Of Two Types Of Fatigue On An Unanticipated Side-Step Cutting Task As Measured By Kinematic And Kinetic Variables, Shawn E. Lucci

Human Movement Studies & Special Education Theses & Dissertations

Fatigue has been shown to alter the neuromechanics of lower extremity. To date, no study has examined the effects of two types of fatigue on kinetics and kinematics. To determine neuromechanical differences between two fatigue protocols [Slow Linear Oxidative Fatigue Protocol (SLO-FP) and Functional Agility Short-Term Fatigue Protocol (FAST-FP)] when performing an unanticipated sidestep cutting task. Fifteen female collegiate soccer players (age=19.2±0.8 years; height=l.67±0.05m; mass=61.7±8.lkg) participated in this study. Participants were free of lower extremity injury at time of participation, and performed five successful trials of a sidestep cutting (SS) task pre and post fatigue protocols. For the SLO-FP, a …