Physiology Commons^™

Long-Term Treatment With Insulin And Retinoic Acid Increased Glucose Usage In L6 Muscle Cells Via Glycogenesis, Matthew Ray Goff

Doctoral Dissertations

Skeletal muscle glucose metabolism can affect whole body glucose homeostasis significantly. Vitamin A (VA) plays a role in a number of physiological functions including glucose metabolism. However, its role in skeletal muscle glucose metabolism has not been well established. Insulin controls glucose metabolism in the skeletal muscle via the regulations of glucose uptake, glycogenesis, and glycolysis. We hypothesize that insulin and VA signaling pathways may converge to regulate glucose metabolism in skeletal muscle. Here, the effects of retinoic acid (RA) alone and in combination with insulin on glucose utilization in rat L6 muscle cells were studied. L6 cells were treated …

The Effects Of Actigraph Bandpass Filtering On Activity Counts During Continuous And Intermittent Lifestyle Activity, Samuel Robert Lamunion

Masters Theses

PURPOSE: The purpose of this study was to explore how increasing the upper limit of the bandpass filter frequency range affected accelerometer counts collected during treadmill walking and running, car driving and intermittent lifestyle activities METHODS: Part A included treadmill walking, running, and car driving (N=20) (mean ± [plus or minus] SD; age, 24.4±3.4 years; body mass index (BMI, 26.4±3.3 kg/m² [kilograms per meter squared]). Part B included ten lifestyle activities ranging from sedentary behaviors to vigorous intensities (N=30) (mean±SD; age, 23.0±2.3 years; BMI, 25.1±3.8 kg/m²). Participants wore an ActiGraph accelerometer (GT3X+ in Part A and GT9X …

Why Is There Still So Much Confusion About Vo2 Plateau? A Re-Examination Of The Work Of A.V. Hill, Richard Vincent Castle

Masters Theses

Maximal oxygen uptake (VO_2max) is regarded as the gold standard for assessing aerobic fitness. In 1923, Hill et al. proposed that VO_2max represents the maximal ability of the body to take in and consume O₂ during strenuous exercise. Recently, however, controversy has arisen over the issue of whether a leveling off, or "plateau" in VO₂ is necessary to verify attainment of VO_2max. Purpose: To compare two different VO_2max protocols and determine if both protocols show direct evidence of an upper limit on VO₂. Methods: Nine runners (18-35 years old) completed …

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.

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 …

Changes In Body Composition And Physical Activity Behavior In A Group Of College Freshmen, Tracy A. Swibas

Masters Theses

PURPOSE: To compare: 1-the physiological profile of former athletes (Ath) and non-athletes (Non-Ath) upon college entrance, 2-PA levels in these groups, and 3-changes in physiological profile and PA level of former Ath and Non-Ath and females and males over the course of freshman year. Sixty-two college freshmen were tested during the initial weeks of the school year and again during the final weeks of the school year; the sample consisted of 32 former Ath (18 females and 14 males) and 30 Non-Ath (19 females and 11 males). METHODS: Body composition (BC) was assessed using the Bod Pod with a conversion …

Physical Activity Levels Of College Freshman: Comparison Of Surveys With Objective Measures Of Physical Activity, Lois Amber Mcmahan

Masters Theses

PURPOSE: This study compared measures of physical activity (PA) taken from the 7- day Physical Activity Recall (PAR) and the International Physical Activity Questionnaire (IPAQ) with those obtained from the NL 2000 (NL) and Lifecorder (LC) accelerometers in entering, college freshmen.

METHODS: 47 males and 64 females (overall age =18.5±.3 yrs, wt. = 68.7±14.4 kg, and BMI = 23.7 ±4.9) volunteered and signed an informed consent form. All subjects wore the NL for 7 days, and half wore the LC as well. After the 7 days the subjects completed the PAR and IPAQ.

RESULTS: There was a strong agreement between …