Theses and Dissertations

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Open Access
State licensing of fitness leaders in Colorado health clubs
(Colorado State University. Libraries, 1981) Legel, John Patrick, author; Morton, Max L., advisor; Lantry, Terry L., committee member; Johnson, M. L., committee member
The purpose of this study was to formulate a legal proposal for licensing of fitness leaders in Colorado health clubs. The subproblems were: 1) to identify present qualifications and educational backgrounds of currently employed fitness supervisors and leaders in the Colorado health club industry, 2) to determine the trend of the law in cases of personal injury resulting from negligence of a health club employee, and 3) to determine the need for a state licensing procedure for fitness leaders in Colorado health clubs. A survey questionnaire was developed and mailed to the managers of the 220 health clubs listed in the 1981 Colorado telephone directory. Percentages and frequency tabulations were used to analyze the results. One hundred nineteen questionnaires were returned, 115 of which contained data suitable for analysis. From the analysis the following conclusions were drawn. 1) The educational background of Colorado health club employees with respect to health and fitness related certifications is low. 2) The educational background of Colorado health club employees with respect to courses taken in one of the nine related areas is low. 3) Only 59 percent of health clubs have a full time employee trained in Cardiopulmonary Resuscitation 4) Only 51 percent of health clubs have a full time employee trained in Advanced First Aid. 5) Fitness leaders receive the major portion of their related education at the university level, with high schools, junior colleges, and health clubs contributing in a minor way. 6) The rapid expansion of knowledge in the exercise field is not being adequately extended to the patrons of health clubs, because about half of the health clubs do not have an employee who has taken related coursework within the last four years. 7) There are no generally accepted standards as to what constitutes a minimum level of knowledge for a fitness leader in the Colorado health club industry. 8) A licensing procedure would be in the self interest of the health club industry. Health club owners could show that they took reasonable care in providing their patrons with knowledgeable personnel, by employing licensed fitness leaders and may thereby reduce their potential liability. Considering the trend of the courts to view liability waivers unfavorably, this becomes important. 9) The conclusions support the need for a state licensing procedure to set a minimum standard of knowledge for fitness leaders, to insure that current and reliable information is being given to the public. From these conclusions the following recommendations are suggested. 1) The minimum standards should be based on the current state of the art as determined by leading authorities in the exercise field. 2) A practical way to achieve these standards would be to initiate a state licensing program that would test and license fitness leaders. 3) Cardiopulmonary Resuscitation should be required. 4) Advanced First Aid should be required. 5) Applicants for a license should be able to demonstrate a basic knowledge of the following topics. a) Exercise Physiology b) Exercise Program Design c) Human Anatomy and Kinesiology d) Diet and Nutrition e) Psychology of Motor Behavior, Sport and Exercise f) Health Evaluation Methods g) Activity Related Injury h) Muscular Training 6) Licenses should be renewed every four years.
Open Access
Acute ascorbic acid administration improves exercise hyperemia during rhythmic but not single contractions in aging humans
(Colorado State University. Libraries, 2009) Simpson, Carrie Beth, author; Dinenno, Frank A., advisor; Earley, Scott, committee member; Bell, Christopher, committee member
Age-related increases in oxidative stress are known to impair endothelium dependent vasodilation in older healthy humans. As a result, many researchers have speculated that endothelial dysfunction contributes to impaired muscle blood flow and vascular control during exercise. Further, elevations in oxidative stress and subsequent endothelial dysfunction could possibly explain our recent observations of impaired contraction-induced rapid vasodilation in older adults. Therefore, we directly tested the hypothesis that acute ascorbic acid administration would augment (1) rapid vasodilation in response to single muscle contractions as well as (2) the hyperemic response to sustained rhythmic contractions in older healthy humans, and that this would be due to improved endothelium-dependent vasodilation. In 14 young (22±1 yrs) and 14 healthy older men and women (65±2 yrs), we measured forearm blood flow (FBF; Doppler ultrasound) and calculated vascular conductance (FVC) responses to single, 1 second dynamic contractions at 10, 20, and 40% maximum voluntary contraction (MVC) before and after intra-arterial administration of ascorbic acid (AA). We also measured these variables during rhythmic handgrip exercise at 10% maximum voluntary contraction. After 5 minutes of steady-state exercise with saline, ascorbic acid (AA) was infused via brachial artery catheter for 10 minutes during continued exercise. For single contractions, prior to AA peak vasodilator responses to all contraction intensities were impaired ~35-50% in older adults (P<0.05), as were the immediate (1st cardiac cycle post contraction) vasodilator responses at 20 and 40% MVC (~50%; P<0.05). In contrast to our hypothesis, AA did not influence contraction-induced rapid vasodilation in either group (all NS). Regarding rhythmic handgrip exercise, FBF (~28%) and FVC (~31%) were lower in older vs young adults (P=0.06 and P<0.05) prior to AA. In young adults, AA administration did not significantly influence FBF and FVC, whereas FBF and FVC increased 30±4% in older adults at end exercise (P<0.05). AA did not influence vasodilator responses to sodium nitroprusside in either group, but significantly improved vasodilation to acetylcholine in older adults only (P<0.05). We conclude that endothelial dysfunction is not the primary mechanism underlying impaired contraction-induced rapid vasodilation with human aging; however acute AA administration increases muscle blood flow during dynamic exercise in older adults, which is likely due to an improvement in endothelium dependent vasodilation.
Open Access
Effects of decoupled elliptical training on interlimb coordination
(Colorado State University. Libraries, 2009) Keene, Abbey Rae, author; Tracy, Brian L., advisor; Stallones, Lorann, committee member; Reiser, Raoul F., II, committee member
During human locomotion, the spinal cord produces predictable alternating muscle activation to the lower limbs to produce functional gait. The Shifter is a novel elliptical trainer with mechanically decoupled foot pads, forcing the user to deliver precisely timed alternating foot forces to maintain cadence. A 15-20 hr training program has been developed to enhance interlimb coordination. Training consists of a demanding progression of increasingly difficult skills that require the user to move their legs independently. PURPOSE: To determine if the training produced neural adaptations that underlie more independent control of the leg muscles. It was hypothesized that progressed subjects (PS) would have enhanced interlimb coordination compared to control subjects (CS), as assessed by suppression of contralateral neural overflow. METHODS: PS (N=5) and CS (N=5) were of similar age, leg press strength, adiposity, and VO2 max (all P>0.05). The subjects exerted an isometric force with the non-dominant knee extensors at 10% of maximal voluntary contraction (MVC) force under two conditions – alone (CF) or with an oscillating task by the dominant leg (OSC). For the OSC task, subjects exerted an oscillating force with the dominant knee extensors at a frequency of 0.25Hz between 0-50% of MVC, without visual feedback. Both the CF and OSC tasks were performed with (VIS) and without (NOVIS) visual force feedback of the non-dominant target force. RESULTS: The force oscillations of the dominant knee extensors were performed at approximately the same frequency, average intensity, and peak force between PS and CS groups for both VIS and NOVIS. For the CS group, during VIS and NOVIS, respectively, the target matching (P=0.015, P=0.004) and control of fluctuations (P = 0.02, P=0.015) for the non-dominant leg was degraded for OSC compared with CF conditions. In contrast, the PS group showed no change in the ability of the non-dominant leg to stay on target (P=0.2) and control force fluctuations (P=0.07) during VIS. During NOVIS the PS group exhibited no change in target matching (P=0.47) and a slight increase in force fluctuations (P= 0.018) between CF and OSC. CONCLUSIONS: These results suggest an adaptation of the nervous system that allowed the PS subjects to reduce the effects of contralateral neural overflow. Prolonged use of the Shifter could produce enhanced interlimb control in rehabilitation, athletic, and elderly populations.
Open Access
Effect of short-term epigallocatechin-3-gallate supplementation on the thermic effect of feeding and resting metabolic rate
(Colorado State University. Libraries, 2009) Lonac, Mark Charles, author; Bell, Christopher, advisor; Hickey, Matthew S., committee member; Nelson-Ceschin, Tracy L., committee member; Melby, Christopher L., committee member
The sympathetic nervous system (SNS) both provides tonic support of resting metabolic rate (RMR) and mediates approximately one-third of the thermic effect of feeding (TEF), the latter accounting for ~10% of daily energy expenditure. Epigallocatechin-3-gallate (EGCG), the most abundant and bioactive catechin in green tea, inhibits the catecholamine-degrading action of the enzyme catechol-O-methyltransferase, thereby prolonging SNS activation. Accordingly, we hypothesized that short-term EGCG supplementation would augment RMR and TEF in healthy adult humans. METHODS: Sixteen subjects reported to our lab on two mornings (≥ 10 days apart) after 12 hours without food, caffeine, and alcohol and 24 hours without exercise. Each visit followed double-blinded, randomized EGCG or cornmeal placebo supplementation (seven pills over 48 hours, 135 mg EGCG/pill). RMR and respiratory exchange ratio (RER) were determined using the ventilated hood technique for 45 minutes prior to consumption of a liquid mixed-composition meal providing calories equivalent to 40% of RMR. Energy expenditure (EE) and RER were then measured for the first 20 of every 30 minutes for five hours. RESULTS: All subjects (n = 9 males, n =7 females; age 25 ± 2 yrs, mean ± s.e.; 22.6 ± 1.8% body fat) were weight stable and were washed out from prior green tea or EGCG use for ≥ one month. Results are reported as placebo vs. EGCG. EGCG did not affect RMR or baseline RER (RMR: 1665 ± 84 vs. 1610 ± 89 kcal/day; p = 0.10; RER: 0.82 ± 0.01 vs. 0.83 ± 0.01; p = 0.29). EGCG did not affect the area under the TEF response curve, expressed as absolute postprandial EE (441,083 ± 22,436 vs. 429,350 ± 24,209 arbitrary units, A.U.; p = 0.22) or the absolute (58,104 ± 5,297 vs. 58,949 ± 5,672 A.U.; p = 0.88) or percentage (3,508 ± 263 vs. 3,647 ± 285 A.U.; p = 0.67) difference between absolute postprandial EE and baseline RMR. No differences between placebo and EGCG were observed for RER during TEF. CONCLUSION: These results indicate that, contrary to our hypothesis, short-term EGCG supplementation does not influence RMR or TEF in healthy adults. This suggests that reported positive benefits of green tea on energy balance are the result of increased physical activity EE and/or decreased energy intake.
Open Access
Physiological strain of firefighters exposed to a live firefighting exercise
(Colorado State University. Libraries, 2009) Barnes, Kyle Russell, author; Hickey, Matthew S., advisor; Israel, Richard Gay, advisor; Jones, Brian, committee member
The physiological demands of occupations such as live urban or wildland firefighting are an important determinant of occupational safety, and can inform decisions about employee recruitment, screening, and training. To this end, the present study describes the physiological strain which attends live burn exercises in an urban firefighter academy. Fourteen firefighters from the Northern Colorado Fire Consortium Fire Academy participated in this investigation. The firefighter cadets’ clinical characteristics were as follows (mean ± SD): age 28.8 ± 5.7 years; height 1.8 ± 0.1 m; mass 83.8 ± 12.9 kg; body mass index (BMI) 26.3 ± 3.0; maximal aerobic capacity 45.0 ± 4.4 ml/kg/min, 3.77 ± 0.6 L/min. Participants were studied during two live burn sessions separated by four days. The mean (± SD) duration of fire exposures was 9.6 ± 1.5 and 9.32 ± 2.6 minutes for day one and two, respectively. The pre-burn heart rates were 92.7 ± 18.0 bpm and 96.4 ± 13.8 bpm in days one and two, respectively. The mean pre-burn blood pressures were 117/68 ± 18.7/9.1 and 122/76 ± 11.0/8.9, respectively. The mean pre-burn blood lactate was 3.3 ± 1.9 mmol/L on day one and 2.7 ± 1.0 mmol/L on day two.
Open Access
Short-term sprint-interval training improves insulin sensitivity in young adult humans
(Colorado State University. Libraries, 2009) Johnson, Tyler Kass, author; Bell, Christopher, advisor; Hickey, Matthew S., advisor; Miller, Benjamin F., committee member; Melby, Christopher L., committee member
Habitual endurance exercise has been shown repeatedly to increase insulin sensitivity, one of the principal determinants of blood glucose control. Many adults however, choose not to participate in this type of exercise, citing insufficient time as a perceived obstacle. A recent study has described improved blood glucose control post-consumption of a glucose beverage following 2-weeks of sprint-interval training (SIT), implying that SIT may increase insulin sensitivity. PURPOSE: Using the gold standard measure, the hyperinsulinemic euglycemic clamp technique, we investigated the hypothesis that SIT will increase insulin sensitivity. METHODS: 12 healthy, sedentary or recreationally active adults (age: 27 ± 3 yr; body mass index: 26.2 ± 1.4 kg/m2; VO2peak: 36.0 ± 3.3 ml/kg/min (mean ± SE)) completed 6 sessions of repeated (4 to 7) 30-second bouts of extremely high-intensity cycle ergometer exercise (i.e. a Wingate protocol) over 14 days. Prior to and 72 hours following completion of SIT the glucose infusion rate (GIR) required to maintain a blood glucose concentration of 90 mg/dL during a standardized infusion of insulin was determined. In order to quantify the effect of the most recent SIT bout on insulin sensitivity, GIR was determined in 7 adults (25 ± 1 yr; 25.7 ± 1.4 kg/m2; 37.1 ± 4.3 ml/kg/min) prior to and 72 hours following a single bout of SIT. Finally, in order to establish the day-to-day variability in GIR, 9 adults (23 ± 2 yr; 26.8 ± 1.6 kg/m2, 33.3 ± 2.2 ml/kg/min) served as a sedentary control. RESULTS: Compared with baseline, insulin sensitivity was increased following short-term SIT (GIR: 6.2 ± 0.7 vs. 8.0 ± 0.8 mg/kg/min; P = 0.02) but was unchanged following a single bout of SIT (9.7 ± 1.3 vs. 10.7 ± 1.4; P = 0.43) or a period of inactivity (7.9 ± 0.9 vs. 8.3 ± 1.0; P = 0.38). Regardless of intervention, blood glucose concentration at the end of the hyperinsulinemic euglycemic clamp, body mass and fasting blood glucose concentration remained unchanged (all P > 0.2), with the exception of a small increase in fasting glucose following a single bout of SIT (73.6 ± 1.8 vs. 75.8 ± 1.3 mg/dL; P = 0.01). CONCLUSION: These data, collected using the gold standard hyperinsulinemic euglycemic clamp technique, suggest that short-term SIT is a viable alternative to endurance training as a strategy to improve insulin sensitivity.
Open Access
Nitric oxide and vasodilating prostaglandins contribute to the augmented skeletal muscle hyperemia during hypoxic exercise in humans
(Colorado State University. Libraries, 2009) Crecelius, Anne Renee, author; Dinenno, Frank A., advisor; Earley, Scott, committee member; Hamilton, Karyn L., committee member
Exercise hyperemia in hypoxia is augmented relative to the same level of exercise in normoxia. At mild exercise intensities, the augmented response is not explained by β-adrenoceptor mediated dilation. We hypothesized that elevated synthesis of nitric oxide (NO) and vasodilating prostaglandins (PGs) contribute to the augmented hyperemic response during hypoxic exercise. To test this hypothesis, in 10 healthy adults, we measured forearm blood flow (FBF; Doppler ultrasound) and calculated the vascular conductance (FVC) responses to rhythmic forearm handgrip exercise (20% maximal voluntary contraction) in normoxia and during systemic isocapnic hypoxia (85% arterial oxygen saturation; pulse oximetry) before and after local intra-brachial combined blockade of nitric oxide synthase (NOS; via NG-monomethyl-ʟ-arginine: ʟ -NMMA) and cyclooxygenase (COX; via ketorolac) inhibition. All trials were performed during local blockade of α- and β-adrenoceptors to eliminate the sympathoadrenal effects on the forearm vasculature and isolate local vasodilation. A deep venous catheter was also placed in the experimental arm. Blood samples were taken from both the arterial and venous catheters and analyzed to assess oxygen extraction and oxygen consumption of the exercising tissue. In control (saline) conditions, FBF after 5 minutes of exercise in hypoxia was greater than in normoxia (345 ± 21 ml min-1 vs 297 ± 18 ml min-1; P<0.05). After NO/PG block, exercise hyperemia was significantly reduced in hypoxia (312 ± 19 ml min-1; P<0.05), but not in normoxia (289 ± 15 ml min-1; P=NS). The observed reduction in FBF during hypoxic exercise after NO/PG block resulted in a significant decrease in oxygen delivery (62 ± 5 ml min-1 vs 56 ± 4 ml min-1; P<0.05). A compensatory increase in extraction was measured (59 ± 3% vs 64 ± 3%; P<0.05) which maintained oxygen consumption (36 ± 3 ml min-1 vs 36 ± 2 ml min-1; P<0.05). We conclude that under the experimental conditions employed, NO and PGs have little role in normoxic exercise hyperemia whereas they significantly contribute to hypoxic exercise hyperemia at this intensity of exercise. The augmented response to hypoxia as compared to normoxia is reduced ~50% with combined NO/PG block. Additionally, during hypoxic exercise after combined NO/PG block, despite a decrease in oxygen delivery driven by attenuated blood flow, muscle oxygen extraction increases to maintain oxygen consumption. The factors contributing to the remaining augmentation of hypoxic exercise hyperemia (~50%) are yet to be determined.
Open Access
Ingestion of wheat germ in healthy subjects does not acutely elevate plasma wheat germ agglutinin concentrations
(Colorado State University. Libraries, 2009) Kuzma, Jessica Nichole, author; Nelson-Ceschin, Tracy L., advisor; Cordain, Loren, 1950-, advisor; Melby, Christopher L., committee member; Hickey, Matthew S., committee member
Because the fiber content (15 g/day) of the typical U.S. diet is considerably lower than recommended values (25-30 g) the public is encouraged by USDA Dietary Guidelines to increase consumption of high fiber foods such as whole grains, fruits, and vegetables. Because whole grains are also a rich source of the lectin wheat germ agglutinin (WGA), those abiding by current recommendations would consequently increase their lectin intake. The WGA lectin has been poorly studied in humans, and it is unclear if it can breach the gut barrier, enter circulation, and influence physiology. Apart from animal studies, characterization of lectin behavior in humans is limited to tomato lectin (TL) and peanut lectin (PNA) feeding studies; both of which were able to detect lectin in systemic circulation within hours of ingestion of tomato juice and peanuts, respectively. Because lectin consumption has elicited adverse health effects in laboratory animals, a prudent first step in humans will be to determine if common dietary lectins such as WGA can enter circulation in quantities capable of influencing normal cell function. The purpose of this study was to determine if WGA enters the circulation of healthy subjects following ingestion of wheat germ and to determine the potential time course and concentration of this lectin in venous plasma. Fourteen normal males and females between 17 and 40 yrs completed preliminary screening and reported to the lab after an overnight fast. Following baseline blood measurements, subjects consumed 50 g wheat germ within a 60 min interval. Blood samples were obtained at 30, 60, 90, 120, 240 min, and at 24 hrs post ingestion. Venous plasma concentrations of WGA were determined via WGA-specific Enzyme-Linked Immunosorbent Assay (ELISA) at the six time intervals, including baseline. According to the protocol utilized, WGA was not detected in venous plasma samples from any of the subjects following consumption of 50 g of wheat germ, thereby indicating that the available WGA in wheat germ either did not breach the gut barrier, or preferentially bound tissues other than plasma proteins. These data represent an important first step in determining the safety of WGA found in common whole-wheat food products. Further research will be required to determine if WGA enters the bloodstream and binds formed elements such as erythrocytes, platelets, and leukocytes in addition to other tissues and organs.
Open Access
Prevalence and correlates of active transportation in university students: a pilot study
(Colorado State University. Libraries, 2010) Hoover, Aubrey Ann, author; Kennedy, Catherine, advisor; Gould, Susan Martin, committee member; Butki, Brian, committee member
Active transportation (AT) affords a practical opportunity to increase physical activity levels, particularly in university students whose environment is especially conducive to an active lifestyle. To promote AT as a viable means to improve activity levels in college students, this study's purpose was to observe existing rates of AT versus passive transportation (PT) between home and campus in Colorado State University students and to analyze any differences in the relationship between determinants of AT and transportation mode. Those determinants of the transportation decision-making process include the transportation environment, demographics and behavioral determinants. A total of 440 students completed a 14-item questionnaire including transportation patterns, demographics and behavioral characteristics. Subjects were assigned a primary mode of transport as a ratio of transport mode for the majority of days of the week related to the number of days on campus. Those with a ratio of exactly .5 (n=31) could not be assigned a primary mode and were, therefore, excluded, leaving 409 subjects. Chi square analysis of the relationship between primary mode of transport and demographic and behavioral characteristics was performed to determine any significant differences. Results revealed that 56.2% of students surveyed primarily used AT and 43.8% used PT. Differences in transportation mode were associated with distance from residence to campus, academic year, self-efficacy and perceived barriers. The majority of students living on campus and within a mile used AT, whereas those living within 1-3 miles or greater than three miles from campus used PT. Freshmen used AT almost exclusively (87.2%), while the majority of sophomores used PT, being the only group to really utilize public transport. Public transport was included with PT due to an unusually short walk time to the bus of three minutes or less. Juniors and seniors did not differ from the overall trend in their use of AT versus PT. Poor perceptions of fitness ability and weight status were associated with greater use of PT. Those selecting PT as their primary mode reported a greater number of barriers to AT; lack of enjoyment and already exercising enough were greater barriers to those using PT than those using AT. Consequently, to promote AT for physical activity in CSU students, efforts should be directed toward those living within 1-3 miles of campus and to freshmen and sophomores as they transition off campus. Additionally, behavioral interventions to improve self-efficacy in those with a poor perception of their fitness level and/or weight status and to minimize the perception of barriers – particularly those associated with PT – would constitute a valid approach.
Open Access
Lower extremity kinematics during walking with snowshoes
(Colorado State University. Libraries, 2010) Kurtz, Rebecca N., author; Reiser, Raoul Frederick, II, advisor; Browning, Raymond, advisor; Jones, Brian, committee member
The popularity of snowshoeing as a form of winter recreation has increased in recent years, due, in part to the development of lightweight snowshoes that provide flotation, traction and stability. However, there is little data on the effects of snowshoes and their design on the biomechanics of walking. PURPOSE: To determine the effects of snowshoes and their frame design on lower extremity kinematics during level and downhill walking. We hypothesized that: 1) lower extremity sagittal plane kinematics would be altered during level snowshoe vs. overground walking; 2) during downhill walking, the use of a snowshoe with a flexible tail frame (flex tail) would reduce ankle plantarflexion and knee flexion angular velocities during early stance. METHODS: Twelve adults (6 males, 6 females, age, 26.7+5.6 yrs, body mass = 68.5±10.7 kg) with prior snowshoe experience completed six, 3-minute level walking trials. Three of the trials were at a walking speed of 1.4 m/s and three were at 0.9 m/s. Subjects walked on packed snow using conventional snowshoes and flex tail snowshoes and overground without snowshoes. In addition, each subject completed two downhill (14º grade) walking trials at a self-selected speed using conventional and flex tail snowshoes. We placed lightweight inertial/gyroscopic sensors on the sacrum, posterior mid-thigh, posterior mid-leg and on the dorsal aspect of the foot. During each trial, we recorded sensor orientation and calculated hip, knee and ankle joint angles and angular velocities. RESULTS: Participants had greater hip and knee flexion during stance and greater hip flexion during swing while snowshoe vs. overground walking on level ground at 1.4 m/s. At 0.9 m/s, subjects had a greater amount of knee flexion during snowshoeing. In addition, ankle plantarflexion began earlier in the gait cycle during snowshoe vs. overground walking. Lower extremity kinematics were similar across snowshoe frame designs during level and downhill walking. CONCLUSIONS: Our results suggest that snowshoeing on packed snow alters lower extremity kinematics resulting in a more flexed leg compared to overground walking. The gait kinematics adopted during snowshoeing may reflect a strategy to limit the effects of having an extended heel on ankle plantarflexion during heel strike.
Open Access
Milk consumption after moderate intensity aerobic exercise improves Nitrogen balance in older adults
(Colorado State University. Libraries, 2010) Jordan, Leora Y., author; Miller, Benjamin F., advisor; Hickey, Matthew S., committee member; Melanson, Ed, committee member; Melby, Christopher L., committee member
Sarcopenia is the progressive decline in muscle mass that happens with age and can lead to falls, fractures, and inability to maintain activities of daily living. Simplistically, sarcopenia results from a disequilibrium in the rates of muscle protein synthesis (MPS) and muscle protein breakdown (MPB), with a net negative protein and nitrogen balance over time. This study was designed to determine whether subjects in energy balance can increase nitrogen balance by timing milk intake immediately after exercise. In a randomized cross-over design, ten older individuals (64.5±2.0 y) completed two 3-day trials that were isocaloric and isonitrogenous. During the two trials, subjects consumed either chocolate milk (PRO+CHO) or a Kool-Aid type beverage (CHO) following a daily bout of cycling exercise (60 minutes at 55% of VO2max). Study diet was repeated across trials and controlled for protein/nitrogen content (1.2 g/kg and 14% of total kcal) and energy balance (within 200 kcal). For all trial days, 24-hour urine collections were completed and analyzed for nitrogen content. Mean energy balance (CHO+PRO: 202±36 kcal; CHO: 191±44 kcal; p=0.68) and mean physical activity level (PAL) (CHO+PRO: 1.61±0.04; CHO: 1.60±0.04; p=0.60) did not differ between trials, but mean nitrogen balance was significantly more positive in the PRO+CHO (1.2 g N±0.32) trial than the CHO trial (0.8 g N ±0.45) (p<0.05). Thus, under conditions of energy balance, nitrogen/protein balance becomes more positive when chocolate milk is consumed immediately after moderate intensity aerobic exercise compared to a CHO-only beverage.
Open Access
Upregulation of heme oxygenase-1 and activation of Nrf2 by the phytochemicals in protandim
(Colorado State University. Libraries, 2010) Reuland, Danielle Judith, author; Hamilton, Karyn L., advisor; Miller, Benjamin F., committee member; Frye, Melinda A., committee member
Increased production of reactive oxygen species has been implicated in the pathogenesis of cardiovascular disease (CVD), with enhanced endogenous antioxidants proposed as a potential mechanism for promoting redox balance. Protandim is a well-defined combination of five widely studied medicinal plants derived from botanical sources [Bacopa monniera, Silybum marianum (milk thistle), Withania somnifera (Ashwagandha), Camellia sinensis (green tea), and Curcuma longa (turmeric)]. The purpose of this study was to determine if treatment of cardiomyocytes with Protandim induces phase II detoxification enzymes, including the endogenous antioxidant heme oxygenase-1 (HO-1), with activation of nuclear factor E2 p45-related factor 2 (Nrf2), and protection from oxidative stress induced apoptosis. In cultured cardiomyocytes, treatment with Protandim was associated with activation of Nrf2 and a significant increase in HO-1. Protandim supplemented cells were protected against hydrogen peroxide-induced apoptosis as assessed by TUNEL (35% apoptotic in untreated vs. 5% apoptotic in Protandim treated). These findings support the use of Protandim as a potential method for upregulation of antioxidant defenses and protection of heart cells against an oxidative challenge. Future studies will focus on optimizing phytochemical induction of Nrf2-mediated antioxidant defenses in relevant in vivo models of CVD.
Open Access
Effects of speed and grade on the biomechanics and energetics of walking in obese adults
(Colorado State University. Libraries, 2010) Ehlen, Kellie Amanda, author; Browning, Raymond, advisor; Reiser, Raoul Frederick, II, committee member; Melby, Christopher L., committee member
Brisk walking is a recommended form of exercise for obese individuals. However, lower extremity joint loads and the associated risk of musculoskeletal injury or pathology increase with walking speed. Walking uphill at a slower speed may offer an alternative form of moderate intensity exercise that reduces joint loading. The purpose of this study was to quantify the biomechanics and energetics of level and uphill walking in obese adults. We hypothesized that compared to brisk level walking, walking slower up a moderate incline would reduce lower extremity joint loading while providing appropriate physiologic stimulus. Twelve obese adult volunteers, age = 27 (5.5) years, mass = 100.5 (15.7) kg, BMI = 33.4 (2.6) kg/m2, (mean (S.D.)), participated in this study. We measured ground reaction forces, three-dimensional lower extremity kinematics and oxygen consumption while subjects walked on a dual-belt force measuring treadmill at several speed (0.50-1.75m/s)/grade (0-9°) combinations. We calculated net muscle moments at the hip, knee and ankle and metabolic rate for each condition. Walking slower uphill significantly reduced net muscle moments at the knee compared to faster level walking (p<0.05). Peak knee extension and adduction moments were reduced by ~19% and 26%, respectively, when subjects walked at 0.75m/s, 6° vs. 1.50m/s, 0°. The greater knee moments during level walking suggests subjects had greater medial compartment knee joint loads. All walking trials were moderate intensity (48.5-59.8% of VO2max). A slower walking speed combined with a moderate incline appears to be an effective strategy for reducing knee joint loads while providing appropriate cardiovascular stimulus in obese adults.
Open Access
Omega-3 fatty acids, lipoprotein-associated phospholipase A₂ and oxidized LDL in glucose sensitive and glucose intolerant males and females
(Colorado State University. Libraries, 2010) Dhara, Jerusa, author; Nelson-Ceschin, Tracy L., advisor; Bizeau, Michael, committee member; Hickey, Matthew S., committee member
Lp-PLA2 is a novel inflammatory marker that has been proposed as an independent risk marker for cardiovascular disease. Lp-PLA2 in circulation is principally bound to low-density lipoprotein cholesterol (LDL-C) in humans and the substrate for the enzyme is provided by the oxidized phospholipid component of LDL-C. In the present study, plasma levels of Lp-PLA2 concentration, activity and plasma levels of oxidized LDL were measured in fifty-nine weight stable adults, mean age 61 years, at baseline and following an 8-week supplementation of ALA, EPA+DHA or control (olive oil). Additionally, glucose, LDL-C, HDL-C, triglycerides and insulin levels were measured at baseline and following the intervention. Fasting blood glucose was measured for the purpose of assessing changes between glucose intolerant and glucose sensitive individuals. Results showed that there was no significant change in the concentration or activity of Lp-PLA2 either in low ox-LDL group or high ox-LDL group after ALA or EPA/DHA supplementation in diet. No particular trend was observed, however, a slight decrease in Lp-PLA2 concentration in all the three groups (CON, ALA, and EPA/DHA) was seen in higher ox-LDL group. But Lp-PLA2 activity only decreased in ALA group (Baseline=163.42 mmol/min/mL + 27.29; week 8 =143.25 mmol/min/mL+14.52) in high ox-LDL group. A minor increase in Lp-PLA2 concentration in the control group (baseline= 206 ng/mL +62.29; week 8= 215.01 ng/mL+73.26) in low ox-LDL group and a slight decrease in Lp-PLA2 activity in control group was observed (baseline= 137.97 mmol/min/mL+ 27.50; week 8= 133.92 mmol/min/mL+28.56). There were no significant changes in fasting plasma ox-LDL after the diet supplementation in any of the groups, but a decreasing trend in LDL-C was observed. In glucose sensitive subjects, a positive correlation between Lp-PLA2 activity and ox-LDL is seen at p<0.01 level. The results of this study also do not represent a baseline significant relation between Lp-PLA2 concentration and activity and ox-LDL in glucose intolerant subjects. The results support the view that Lp-PLA2 is associated with ox-LDL, but do not provide any evidence that omega-3 fats mediate the inflammatory process via Lp-PLA2 or ox-LDL.
Open Access
Effects of fatigue on bilateral ground reaction force asymmetries during the squat exercise
(Colorado State University. Libraries, 2010) Hodges, Stephanie, author; Reiser, Raoul Frederick, II, advisor; Puttlitz, Christian Matthew, committee member; Browning, Raymond, committee member
Physical performance and risk for injury have been related to functional asymmetries of the lower extremity. The squat exercise is an important, functional movement serving as the major multi-joint, closed-chain lower extremity exercise in many strength and conditioning programs, as well as a large component in rehabilitation. Examinations of asymmetries during the squat exercise have revealed bilateral differences in the net joint torques, indicating unequal actions between the lower extremities. To date, no study has examined how fatigue affects these asymmetries. PURPOSE: The goal of this investigation was to examine functional bilateral asymmetries of the lower extremities during the squat exercise, exploring how they may change during the course of an individual set, as well as across multiple sets with fatigue. Based on a review of literature related to the effects of fatigue on functional asymmetries, it was hypothesized that asymmetries would increase with fatigue. METHODS: Seventeen recreationally trained men (n=9) and women (n=8) (mean ± SD age: 22.3 ± 2.5 yrs; height 170 ± 9.3 cm; mass 73.4 ± 13.8 kg) performed five sets of eight repetitions with 90% of their predetermined eight-repetition maximum (8RM 113 ± 35 % of their body mass). Anthropometric measurements and vertical ground reaction force (GRFv) data were collected. GRFv asymmetries were calculated by subtracting the % load on the right foot from that of the left foot. Initially highly symmetric subjects (± 1.7%) were removed from the analyses. The first two (R1&2) and last two (R7&8) repetitions of each set were examined. Eight subjects were reassessed for repeatability measures. RESULTS: R7&8 took longer to complete than R1&2 within a single set (p<0.001), however this finding was not observed across sets (p=0.867). The average asymmetry level across all sets for the absolute average was 4.3 ± 2.5% and 3.6 ± 2.3% for R1&2 and R7&8, respectively. There was no difference in whole group analysis (n=17) for any of the GRFv asymmetry analyses. Initially symmetric subjects were removed for the following analyses. For absolute peak instantaneous forces, the average asymmetry level across all sets was 3.8 ± 2.3% and 3.2 ± 2.3% for R1&2 and R7&8, respectively. Within a set, based on absolute asymmetry, levels of asymmetry dropped from beginning to end of a set (p=0.044). Exploring general shifts towards the left or right leg revealed a significant difference in peak instantaneous asymmetry with subjects becoming more symmetric with fatigue during the course of a single set (p=0.042). Of those who placed more weight on their right side at the beginning of a set, based on average asymmetry, a significant movement towards symmetry was seen for repetitions within a single set (p=0.036). Anthropometrics (segment lengths and circumferences) were generally not highly correlated to the asymmetries. Anthropometric measures were highly repeatable (Cronbach's α≥0.905, p≤0.003), as were time and asymmetry assessments of the squat GRFv asymmetries from visit to visit (Cronbach's α≥0.733, p≤0.056). CONCLUSION: These results suggest that functional asymmetries though low were present, and remained consistent, in this healthy population during a squat exercise. Contrary to the hypothesis, asymmetries did not increase with fatigue, however time to complete each repetition within a set increased with fatigue. Healthy subjects appear to load limbs similarly, subjecting them to a relatively similar training stimulus.
Open Access
On the role of circulating ATP in vascular control at rest and during exercise of aging humans
(Colorado State University. Libraries, 2010) Kirby, Brett Sean, author; Dinenno, Frank A., advisor; Earley, Scott, 1963-, committee member; Chicco, Adam J., committee member; Gotshall, Robert William, 1945-, committee member
The following investigation composes a series of experiments with the overall aim of determining the role for the circulating nucleotide adenosine triphosphate (ATP) in vascular control at rest and during exercise in humans of advanced age. We tested the general hypothesis that ATP has definite vasodilator and sympatholytic vasomotor properties in young adults during exercise, but that these actions are impaired in older adults; and that endogenously circulating levels of ATP are diminished during exercise in the aged population. Specifically, the experiments are outlined as such: 1) to determine whether exogenous ATP can modulate α-adrenergic vasoconstriction in the human forearm of young adults, 2) to determine whether vasodilator responsiveness to exogenous ATP is impaired in aging humans, and the contribution of adenosine to ATP-mediated vasodilation in aging humans, 3) to determine whether the ability of exogenous ATP to modulate α-adrenergic vasoconstriction in the human forearm of older adults is impaired similar to the typical response observed during exercise in aged humans, 4) to determine whether endogenous venous plasma [ATP] and ATP release is diminished during mild-to-moderate exercise in aging humans. Our collective findings indicate that alterations in the contribution of ATP to vascular tone in aging humans exist and may in part be a potential mechanism by which aged adults have reductions in oxygen delivery to active skeletal muscle. In particular, circulating exogenous ATP has the ability to significantly blunt α-adrenergic vasoconstriction in young adults similar to that observed during exercise. In contrast to our hypothesis, the vasodilatory responsiveness and sympatholytic properties of exogenous ATP remain intact in aging humans. However, older adults demonstrate reduced venous plasma [ATP] and impaired ATP release during graded mild-to-moderate handgrip exercise which is associated with attenuations in skeletal muscle vasodilation and blood flow. Taken together, it is our belief that the typically observed impairments in skeletal muscle vasodilation and the inability to offset sympathetic vasoconstrictor tone during exercise is in part due to diminished endogenous levels of circulating ATP in aging humans. On the whole, ATP appears to be a significant regulator of vascular control in humans, and may act as a potential mechanism which in part explains the typically observed reductions in skeletal muscle blood flow and oxygen delivery to active tissue in aged humans thereby predisposing this population to an elevated risk for cardiovascular diseases, age-related declines in exercise capacity/tolerance, and an overall decline in quality of life in this population.
Open Access
T cell mediated satellite cell function: implications for age-associated changes in skeletal muscle regeneration
(Colorado State University. Libraries, 2010) Dumke, Breanna R., author; Lees, Simon J., advisor; Gotshall, Robert W., advisor; Frye, Melinda A., committee member
Sarcopenia is an age-associated loss of skeletal muscle mass and strength. Recent evidence suggests that an age-associated loss of muscle precursor cell (MPC) functionality contributes to sarcopenia. Current research also suggests that T cells of the immune system may influence skeletal muscle repair via signaling with MPCs. The objective of the present study was to examine the influence of activated T cells on MPCs. MPCs were collected from the gastrocnemius and plantaris from 3-mo-old (young) and 32-mo-old (old) animals. Splenic T cells were also harvested using anti-CD3 Dynabead isolation. T cells were activated for 48 hours with co-stimulation of 100 IU/ml Interleukin-2 (IL-2) and 5 ug/ml of anti-CD28. Co-stimulation increased 5-bromo-2'-deoxyuridine (BrdU) incorporation (proliferation) of T cells from 13.382% (SEM=4.55, n=5) in control to 64.77% (SEM= 6.02, n=5). Additionally, T cell cytokines increased MPC proliferation by 23.98% (SEM=5.69, n=4) in young MPCs but decreased by 1.58% (SEM=4.09, n=4) in old MPCs. T cell cytokines were also found to be chemoattractant. Young MPCs migrated at a rate of 1.36 (SEM=0.56, n=4) with T cell cytokines. Old MPCs, however, did not migrate with T cell cytokines -0.05 (SEM= 0.214, n=4). These data suggest that T cells may play a critical role in mediating MPC function. Furthermore, aging may alter T cell-induced MPC function. These findings have implications for developing strategies aimed at increasing MPC proliferation and the regenerative capacity of aged skeletal muscle.
Open Access
Objectively measured free-living physical activity in pet dogs: relationship to body condition score and owner-pet activity
(Colorado State University. Libraries, 2011) Weber, David Isaiah Sale, author; Browning, Raymond C., advisor; Nelson, Tracy, committee member; Palmer, Ross, committee member
The prevalence of canine obesity continues to increase and is due, in part, to inadequate levels of physical activity (PA). Accelerometers have emerged as a useful tool to objectively quantify levels of physical activity in humans, as well as companion pets, but there is little data on the levels/patterns of free-living physical activity in pet dogs and how it relates to body condition score (BCS) and owner physical activity. PURPOSE: To quantify free-living physical activity levels of healthy pet dogs using a collar-mounted accelerometer and to relate this to BCS and owner-reported dog walking behavior. MATERIALS AND METHODS: We recorded anthropometric data, BCS and five consecutive days of free-living physical activity via accelerometry in 74 dogs. Four consecutive days of one-minute accelerometer count epochs were summed to generate a measure of hourly and total daily physical activity levels. We also recorded step counts in 49 owners who were instructed to wear a hip-mounted pedometer while walking their dog and record the number of steps following each walk. RESULTS: Mean (SE) accelerometer counts/day were 202,859(5,806). Dogs with a BCS of three were significantly more active than those with a BCS of four (p= 0.047). Dogs were more physically active in the morning and evening hours, presumably because their owners were present. Dogs appeared to engage in distinct periods of PA such that 40% or more of total daily activity occurred during three hours or ~12% of each day. We analyzed 169 days of owner walks. Mean (SE) accelerometer counts recorded during a walk and corresponding pedometer counts were 95,905(5,637) and 4,558(305) respectively. There was a significant positive relationship between accelerometry counts and steps (r2 0.63, p<0.001). DISCUSSION: These data support the use of accelerometry to assess free-living physical activity in dogs and show that physical activity levels of dogs are inversely related to their adiposity. The strong relationship between dog physical activity and owner dog-walking suggests that interventions aimed to increase walking in dogs may benefit both the dogs and their owners. Accelerometers may be useful in a clinical setting to measure the effects of such interventions. The prevalence of canine obesity continues to increase and is due, in part, to inadequate levels of physical activity (PA). Accelerometers have emerged as a useful tool to objectively quantify levels of physical activity in humans, as well as companion pets, but there is little data on the levels/patterns of free-living physical activity in pet dogs and how it relates to body condition score (BCS) and owner physical activity. PURPOSE: To quantify free-living physical activity levels of healthy pet dogs using a collar-mounted accelerometer and to relate this to BCS and owner-reported dog walking behavior. MATERIALS AND METHODS: We recorded anthropometric data, BCS and five consecutive days of free-living physical activity via accelerometry in 74 dogs. Four consecutive days of one-minute accelerometer count epochs were summed to generate a measure of hourly and total daily physical activity levels. We also recorded step counts in 49 owners who were instructed to wear a hip-mounted pedometer while walking their dog and record the number of steps following each walk. RESULTS: Mean (SE) accelerometer counts/day were 202,859(5,806). Dogs with a BCS of three were significantly more active than those with a BCS of four (p= 0.047). Dogs were more physically active in the morning and evening hours, presumably because their owners were present. Dogs appeared to engage in distinct periods of PA such that 40% or more of total daily activity occurred during three hours or ~12% of each day. We analyzed 169 days of owner walks. Mean (SE) accelerometer counts recorded during a walk and corresponding pedometer counts were 95,905(5,637) and 4,558(305) respectively. There was a significant positive relationship between accelerometry counts and steps (r2 0.63, p<0.001). DISCUSSION: These data support the use of accelerometry to assess free-living physical activity in dogs and show that physical activity levels of dogs are inversely related to their adiposity. The strong relationship between dog physical activity and owner dog-walking suggests that interventions aimed to increase walking in dogs may benefit both the dogs and their owners. Accelerometers may be useful in a clinical setting to measure the effects of such interventions.
Open Access
A single high-altitude training bout improves high-altitude aerobic performance following one week of low altitude training
(Colorado State University. Libraries, 2011) Andersen, Brady Dean, author; Chicco, Adam J., advisor; Hickey, Matthew Sean, committee member; Gotshall, Robert William, 1945-, committee member; Turk, Daniel E. (Daniel Ernest), 1961-, committee member
Consecutive bouts of aerobic exercise at high-altitude are known to improve subsequent aerobic exercise performance at high altitude due to a variety of acute and chronic adaptations referred to as altitude acclimatization. However, it is unclear whether these benefits can be elicited by a single bout of high-altitude exercise followed by several days of training at lower altitude. PURPOSE: We investigated whether a single bout of hill running exercise performed at high-altitude improves running performance, arterial oxygen saturation (SaO2), hematocrit (HCT) and perceived exertion (RPE) during a strenuous timed run at high-altitude performed 1 week following the training stimulus. METHODS: Participants were well-trained competitive runners (VO2 max 52 ± 5 ml/kg/min, aged 42 ± 14 yrs, n = 8) living in Fort Collins, CO (5,003 ft) that were naïve to higher altitudes for at least 8 weeks. All were training regularly (66 ± 3 miles/wk) and refrained from any non-prescribed altitude exposure for the duration of the study. Baseline testing consisted of a timed run on the Mt. Evans Scenic Byway in Colorado (11.5 miles at 11,500-14,100 ft) followed by one week of training in Fort Collins. Runners were then randomized to perform a 12 mile hill running workout in Fort Collins (LOW; 5,550-7,170 ft, n = 4) or Mt. Evans (HIGH; 12,750-14,100 ft, n = 4). All runners then engaged in 1 week of routine training in Fort Collins followed by a post-test run at Mt. Evans that was identical to the baseline test. RESULTS: There were no significant differences in run-time from pre to post-test for either group. Pre-run (11,500 ft) percent change in SaO2 was significantly different between groups (+3.70 ± 2.95% in High; -3.95 ± 1.62% in Low, P = 0.029). The high group experienced a 4.01 ± 2.72% mean increase in exercising SaO2 from pre to post-test, while the Low group decreased 1.21 ± 1.41% from pre to post-test (P = 0.029). In addition, the High group experience a 8.45 ± 8.13% increase in recovery SaO2 from pre to post-test at an elevation of 14,100 feet, while the Low group had a 2.21 ± 2.82% decrease in recovery SaO2 from pre to post-test at an elevation of 14,100 feet (P = 0.057) . HCT increased from pre post-test to post post-test in the Low group only (43.55 ± 1.04% & 45.67 ± 0.79% respectively; P = 0.68). There were no differences in HR or RPE within or between High and Low groups. CONCLUSION: A single high-altitude training bout prior to 1 week of low-altitude training improves subsequent aerobic performance and arterial O2 saturation at high-altitude, while a single bout performed 2 weeks prior to testing is ineffective.
Open Access
Lipids and oxidative stress as mediators of endothelial pathophysiology in obesity
(Colorado State University. Libraries, 2011) Donovan, Elise Laura, author; Miller, Benjamin F., advisor; Hamilton, Karyn L., advisor; Hickey, Matthew S., committee member; Frye, Melinda A., committee member
Because obesity is a well established independent risk factor for diabetes and coronary artery disease (CAD), it is important to identify factors associated with obesity that are responsible for disease progression and interventions to decrease risk of developing obesity associated co-morbidities. Two of the many mediators of obesity associated risk for diabetes and CAD are oxidative stress and oxidized phospholipids, which have been implicated in vascular disease initiation and progression through endothelial cell activation, macrophage recruitment and advanced plaque rupture. Plasma platelet activating factor acetylhydrolase (Lp-PLA2) is an enzyme that circulates bound to LDL cholesterol and degrades platelet activating factor (PAF), a potent inducer of the platelet coagulation cascade and thrombosis. In addition, Lp-PLA2 degrades oxidized phospholipids to lysophospholipid products and fatty acids that may also induce inflammatory changes in multiple cell types, including vascular endothelial cells. Exogenous antioxidant supplementation has been examined as a means of decreasing vascular oxidative stress. However, data show that exogenous antioxidant supplementation has little or no effect on CVD outcomes, and in some cases it may increase mortality. A novel approach to protecting cells from oxidative stress is to increase cellular endogenous antioxidant defenses. NF-E2-related factor 2 (Nrf2) is a transcription factor that binds to the antioxidant response element (ARE) promoter region of many genes including phase II antioxidant enzymes. Protandim is a combination of phytochemicals that is thought to induce Nrf2 stabilization and translocation to the nucleus, with subsequent increases in phase II antioxidant enzymes and protection against oxidative stress. The overall objectives of the three studies we performed were to 1) globally analyze obesity associated lipid and oxidative stress using lipidomics techniques 2) determine the effects of identified obesity associated oxidative and lipid stress on the vascular endothelium 3) determine whether Protandim treatment could protect vascular endothelial cells from an oxidative challenge, and 4) characterize Lp-PLA2 in human adipose and skeletal muscle. Experiment 1 tested the hypothesis that oxidized phospholipids would be greater in morbidly obese gastric bypass patients compared to lean surgical controls, and that global lipid profiles would differ between groups. To test this hypothesis we performed a combined targeted and global lipidomic analysis of plasma lipids from morbidly obese gastric bypass patients and lean controls. We identified a group of ether-linked lipids that were greater in obese subjects compared to lean, and further examined whether a representative lipid from this group induced pathophysiological phenotypic changes in vascular endothelial cells. Experiment 2 tested the hypothesis that Protandim would protect human coronary artery endothelial cells (HCAEC) against an oxidative challenge by increasing phase II antioxidant enzymes in a Nrf2 dependent manner. To do this we performed a series of in vitro experiments treating HCAEC with Protandim and determined that Protandim induced Nrf2 nuclear localization, increased phase II antioxidant enzyme expression, and protected cells from undergoing apoptosis in response to an oxidative challenge. Silencing Nrf2 prior to the oxidative challenge inhibited the Protandim induced protection. Experiment 3 tested the hypothesis that Lp-PLA2 would be detectable in human adipose tissue and that Lp-PLA2 would be greater in adipose from morbidly obese gastric bypass patients compared to lean. In addition, we examined whether adipose Lp-PLA2 may be related to circulating Lp-PLA2 activity, inflammation, and glucose intolerance. We have identified ether-linked lipids that are elevated in obese subjects compared to lean. We found that Lp-PLA2 is expressed in human adipose for the first time, adipose Lp-PLA2 is co-localized with macrophages, and report relationships between Lp-PLA2 and indices of glucose homeostasis and inflammation. Lastly, we found that Protandim protects endothelial cells from an oxidative challenge in a Nrf2 dependent manner. Collectively, these data provide insight into the oxidative and lipid stress milieu that occurs in obese subjects.