Exercise Science Commons^™

Circulating Angiogenic Cell Population Responses To 10 Days Of Reduced Physical Activity, Gayatri Guhanarayan, Julianne Jablonski, Sarah Witkowski

Exercise and Sport Studies: Faculty Publications

Circulating angiogenic cells (CACs) are a diverse group that have been identified as predictors of cardiovascular health and are inversely proportional to cardiovascular disease (CVD) outcomes. Inactivity is a growing concern in industrialized nations and is an independent risk factor for CVD. There is limited evidence regarding the impact of reduced physical activity (rPA) on different CAC populations. The purpose of this study was to evaluate the effect of objectively monitored rPA with maintained energy balance on two CAC populations (CFU and CD34+cells), intracellular nitric oxide (NOi), and genes related to NO production in active, healthy men. Participants (age 25 …

Defining The "Dose" Of Altitude Training: How High To Live For Optimal Sea Level Performance Enhancement, Robert F. Chapman, Trine Karlsen, Geir K. Resaland, R. L. Ge, Matthew P. Harber, Sarah Witkowski, James Stray-Gundersen, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

Defining the "dose" of altitude training: how high to live for optimal sea level performance enhancement. J Appl Physiol 116: 595-603, 2014. First published October 24, 2013; doi:10.1152/japplphysiol.00634.2013.-Chronic living at altitudes of 2,500 m causes consistent hematological acclimatization in most, but not all, groups of athletes; however, responses of erythropoietin (EPO) and red cell mass to a given altitude show substantial individual variability. We hypothesized that athletes living at higher altitudes would experience greater improvements in sea level performance, secondary to greater hematological acclimatization, compared with athletes living at lower altitudes. After 4 wk of group sea level training and …

Sex-Specific Effects Of Exercise Ancestry On Metabolic, Morphological And Gene Expression Phenotypes In Multiple Generations Of Mouse Offspring, Lisa M. Guth, Andrew T. Ludlow, Sarah Witkowski, Mallory R. Marshall, Laila C.J. Lima, Andrew C. Venezia, Tao Xiao, Mei Ling Ting Lee, Espen E. Spangenburg, Stephen M. Roth

Exercise and Sport Studies: Faculty Publications

New findings: • What is the central question of this study? How does parental exercise training directly and/or transgenerationally affect offspring phenotypes over two generations of mice? • What is the main finding and what is its importance? We observed preliminary evidence that parental exercise training can influence health-related phenotypes (e.g. body and fat mass, muscle gene expression) in mouse offspring. These findings indicate that parental exercise may be another environmental factor (like altered nutrition) capable of influencing offspring phenotypes in adulthood. Early life and preconception environmental stimuli can affect adult health-related phenotypes. Exercise training is an environmental stimulus affecting …

Individuals With Non-Specific Low Back Pain In An Active Episode Demonstrate Temporally Altered Torque Responses And Direction-Specific Enhanced Muscle Activity Following Unexpected Balance Perturbations, Stephanie L. Jones, Juvena R. Hitt, Michael J. Desarno, Sharon M. Henry

Exercise and Sport Studies: Faculty Publications

Individuals with a history of non-specific low back pain (LBP) while in a quiescent pain period demonstrate altered automatic postural responses (APRs) characterized by reduced trunk torque contributions and increased co-activation of trunk musculature. However, it is unknown whether these changes preceded or resulted from pain. To further delineate the relationship between cyclic pain recurrence and APRs, we quantified postural responses following multi-directional support surface translations, in individuals with non-specific LBP, following an active pain episode. Sixteen subjects with and 16 without LBP stood on two force plates that were translated unexpectedly in 12 directions. Net joint torques of the …

Chronic Exercise Modifies Age-Related Telomere Dynamics In A Tissue-Specific Fashion, Andrew T. Ludlow, Sarah Witkowski, Mallory R. Marshall, Jenny Wang, Laila C.J. Lima, Lisa M. Guth, Espen E. Spangenburg, Stephen M. Roth

Exercise and Sport Studies: Faculty Publications

We evaluated the impact of long-term exercise on telomere dynamics in wild-derived short telomere mice (CAST/Ei) over 1 year. We observed significant telomere shortening in liver and cardiac tissues in sedentary 1-year-old mice compared with young (8 weeks) baseline mice that were attenuated in exercised 1-year-old animals. In contrast, skeletal muscle exhibited significant telomere shortening in exercise mice compared with sedentary and young mice. Telomerase enzyme activity was increased in skeletal muscle of exercise compared with sedentary animals but was similar in cardiac and liver tissues. We observed significant age-related decreases in expression of telomere-related genes that were attenuated by …

Individuals With Non-Specific Low Back Pain Use A Trunk Stiffening Strategy To Maintain Upright Posture, Stephanie L. Jones, Sharon M. Henry, Christine C. Raasch, Juvena R. Hitt, Janice Y. Bunn

Exercise and Sport Studies: Faculty Publications

There is increasing evidence that individuals with non-specific low back pain (LBP) have altered movement coordination. However, the relationship of this neuromotor impairment to recurrent pain episodes is unknown. To assess coordination while minimizing the confounding influences of pain we characterized automatic postural responses to multi-directional support surface translations in individuals with a history of LBP who were not in an active episode of their pain. Twenty subjects with and 21 subjects without non-specific LBP stood on a platform that was translated unexpectedly in 12 directions. Net joint torques of the ankles, knees, hips, and trunk in the frontal and …

A History Of Low Back Pain Associates With Altered Electromyographic Activation Patterns In Response To Perturbations Of Standing Balance, Jesse V. Jacobs, Sharon M. Henry, Stephanie L. Jones, Juvena R. Hitt, Janice Y. Bunn

Exercise and Sport Studies: Faculty Publications

People with a history of low back pain (LBP) exhibit altered responses to postural perturbations, and the central neural control underlying these changes in postural responses remains unclear. To characterize more thoroughly the change in muscle activation patterns of people with LBP in response to a perturbation of standing balance, and to gain insight into the influence of early- vs. late-phase postural responses (differentiated by estimates of voluntary reaction times), this study evaluated the intermuscular patterns of electromyographic (EMG) activations from 24 people with and 21 people without a history of chronic, recurrent LBP in response to 12 directions of …

Plasma Fetuin-A Concentrations In Young And Older High- And Low-Active Men, Nathan T. Jenkins, Jennifer A. Mckenzie, James M. Hagberg, Sarah Witkowski

Exercise and Sport Studies: Faculty Publications

Fetuin-A is a liver-derived factor that may play a role in insulin resistance and age-related chronic diseases (eg, type 2 diabetes mellitus and cardiovascular [CV] disease). Regular exercise improves CV risk and insulin sensitivity; however, it is unknown whether chronic exercise training is related to circulating levels of fetuin-A. Therefore, this study examined whether plasma fetuin-A levels were related to age and chronic physical activity in men. We hypothesized that chronic physical activity would be related to lower plasma fetuin-A levels in younger and older men. In healthy high-active (HI) and low-active (LO) young (HI, n = 7; LO, n …

Akt1 G205t Genotype Influences Obesity-Related Metabolic Phenotypes And Their Responses To Aerobic Exercise Training In Older Caucasians, Jennifer A. Mckenzie, Sarah Witkowski, Andrew T. Ludlow, Stephen M. Roth, James M. Hagberg

Exercise and Sport Studies: Faculty Publications

As part of the insulin signalling pathway, Akt influences growth and metabolism. The AKT1 gene G205T (rs1130214) polymorphism has potential functional effects. Thus, we determined whether the G205T polymorphism influences metabolic variables and their responses to aerobic exercise training. Following dietary stabilization, healthy, sedentary, 50- to 75-year-old Caucasian men (n= 51) and women (n= 58) underwent 6 months of aerobic exercise training. Before and after completing the intervention, dual-energy X-ray absorptiometry was used to measure percentage body fat, computed tomography to measure visceral and subcutaneous fat, and oral glucose tolerance testing to measure glucose total area under the curve (AUC), …

High-Frequency Electrically Stimulated Skeletal Muscle Contractions Increase P70S6k Phosphorylation Independent Of Known Igf-I Sensitive Signaling Pathways, Sarah Witkowski, Richard M. Lovering, Espen E. Spangenburg

Exercise and Sport Studies: Faculty Publications

Insulin-like growth factor (IGF-I) is hypothesized to be a critical upstream regulator of mammalian target of rapamycin (mTOR)-regulated protein synthesis with muscle contraction. We utilized a mouse model that expresses a skeletal muscle specific dominant-negative IGF-I receptor to investigate the role of IGF-I signaling of protein synthesis in response to unilateral lengthening contractions (10 sets, 6 repetitions, 100. Hz) at 0 and 3. h following the stimulus. Our results indicate that one session of high frequency muscle contractions can activate mTOR signaling independent of signaling components directly downstream of the receptor.

Thrombin And Exercise Similarly Influence Expression Of Cell Cycle Genes In Cultured Putative Endothelial Progenitor Cells, Michael M. Lockard, Sarah Witkowski, Nathan T. Jenkins, Espen E. Spangenburg, Thomas O. Obisesan, James M. Hagberg

Exercise and Sport Studies: Faculty Publications

Acute exercise and exercise training may influence putative endothelial progenitor cell (EPC) number and colony forming units (CFU-ECs), although the mechanisms remain unclear. This study examined the effects of in vitro thrombin supplementation and acute exercise on CFU-EC gene expression, associated with cellular proliferation and differentiation. The effect of habitual physical activity was evaluated through analysis of EPCs from chronically high- and low-active men. Participants were healthy high- and low-active men (n = 23), aged 55-80 yr. Circulating CD34+/VEGFR2+ number, CFU-ECs, plasma prothrombin fragment (F1+2), and thrombin-antithrombin III were measured at rest and after 30 min of exercise. Gene expression …

Endurance Exercise Training Effects On Body Fatness, Vo2max Hdl-C Subfractions, And Glucose Tolerance Are Influenced By A Plin Haplotype In Older Caucasians, Nathan T. Jenkins, Jennifer A. Mckenzie, Coleen M. Damcott, Sarah Witkowski, James M. Hagberg

Exercise and Sport Studies: Faculty Publications

Perilipins are lipid droplet-coating proteins that regulate intracellular lipolysis in adipocytes. A haplotype of two perilipin gene (PLIN) single nucleotide polymorphisms, 13041A>G and 14995A>>T, has been previously associated with obesity risk. Furthermore, the available data indicate that this association may be modified by sex. We hypothesized that this haplotype would associate with body fatness, aerobic fitness, and a number of cardiovascular (CV) risk factor phenotypes before and after a 6-mo endurance exercise training program in sedentary older Caucasians. The major haplotype group (13041A/14995A; n = 57) had significantly lower body mass index (BMI) and body fatness compared with …

Relationship Between Circulating Progenitor Cells, Vascular Function And Oxidative Stress With Long-Term Training And Short-Term Detraining In Older Men, Sarah Witkowski, Michael M. Lockard, Nathan T. Jenkins, Thomas O. Obisesan, Espen E. Spangenburg, James M. Hagberg

Exercise and Sport Studies: Faculty Publications

Exercise may contribute to the maintenance of vascular function via enhanced liberation and action of bone-marrow-derived progenitor cells. Activity related changes in oxidative stress may also influence the number and function of these cells. In the present study, we sought to determine (i) whether adaptations in reactive hyperaemic FBF (forearm blood flow) response associated with long-term endurance exercise and short-term detraining were related to resting putative progenitor cell number and function, and (ii) whether oxidative stress affected these factors. Participants included men with a history of more than 30 years of moderate-to-high-intensity exercise (HI group) and healthy low-active age- and …

Effects Of Acute And Chronic Endurance Exercise On Intracellular Nitric Oxide In Putative Endothelial Progenitor Cells: Role Of Napdh Oxidase, Nathan T. Jenkins, Sarah Witkowski, Espen E. Spangenburg, James M. Hagberg

Exercise and Sport Studies: Faculty Publications

We sought to delineate the effects of acute and chronic exercise on the regulation of intracellular nitric oxide (NOi) production in putative endothelial progenitor cells (EPCs). Putative EPC colony-forming units (CFUEC) were cultured from blood drawn before and after 30 min of treadmill exercise at 75% of maximal oxygen uptake in active (n = 8) and inactive (n = 8) men. CFU-EC were similar between groups at baseline, but increased after exercise in active men only (P = 0.04). CFU-EC expressed lower NADPH oxidase subunit gp91 phox mRNA and elevated endothelial nitric oxide synthase mRNA in active relative to inactive …

Exercise, Apoe, And Working Memory: Meg And Behavioral Evidence For Benefit Of Exercise In Epsilon4 Carriers, Sean P. Deeny, David Poeppel, Jo B. Zimmerman, Stephen M. Roth, Josef Brandauer, Sarah Witkowski, Joseph W. Hearn, Andrew T. Ludlow, José L. Contreras-Vidal, Jason Brandt, Bradley D. Hatfield

Exercise and Sport Studies: Faculty Publications

Performance on the Sternberg working memory task, and MEG cortical response on a variation of the Sternberg task were examined in middle-aged carriers and non-carriers of the APOE ε4 allele. Physical activity was also assessed to examine whether exercise level modifies the relationship between APOE genotype and neurocognitive function. Regression revealed that high physical activity was associated with faster RT in the six- and eight-letter conditions of the Sternberg in ε4 carriers, but not in the non-carriers after controlling for age, gender, and education (N = 54). Furthermore, the MEG analysis revealed that sedentary ε4 carriers exhibited lower right temporal …

Relationship Between Physical Activity Level, Telomere Length, And Telomerase Activity, Andrew T. Ludlow, Jo B. Zimmerman, Sarah Witkowski, Joe W. Hearn, Bradley D. Hatfield, Stephen M. Roth

Exercise and Sport Studies: Faculty Publications

The purpose of this study was to examine the relationship of exercise energy expenditure (EEE) with both telomere length and telomerase activity in addition to accounting for hTERT C-1327T promoter genotype.

Progenitor Cells And Age: Can We Fight Aging With Exercise?, Sarah Witkowski, James M. Hagberg

Exercise and Sport Studies: Faculty Publications

No abstract provided.

Transcranial Doppler Estimation Of Cerebral Blood Flow And Cerebrovascular Conductance During Modified Rebreathing, Jurgen A.H.R. Claassen, Rong Zhang, Qi Fu, Sarah Witkowski, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

Clinical transcranial Doppler assessment of cerebral vasomotor reactivity (CVMR) uses linear regression of cerebral blood flow velocity (CBFV) vs. end-tidal CO2 (PETCO2) under steady-state conditions. However, the cerebral blood flow (CBF)-PETCO2 relationship is nonlinear, even for moderate changes in CO2. Moreover, CBF is increased by increases in arterial blood pressure (ABP) during hypercapnia. We used a modified rebreathing protocol to estimate CVMR during transient breath-by-breath changes in CBFV and PETCO2. Ten healthy subjects (6 men) performed 15 s of hyperventilation followed by 5 min of rebreathing, with supplemental O2 to maintain arterial oxygen saturation constant. To minimize effects of changes …

Cerebral Hemodynamics After Short- And Long-Term Reduction In Blood Pressure In Mild And Moderate Hypertension, Rong Zhanf, Sarah Witkowski, Qi Fu, Jurgen A.H.R. Claassen, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

This study tested the hypothesis that acute reduction in blood pressure (BP) at the initial stage of antihypertensive therapy compromises brain perfusion and dynamic cerebral autoregulation in patients with hypertension. Cerebral blood flow velocity and BP were measured in patients with mild and moderate hypertension and in healthy volunteers at baseline upon reduction of BP within 1 to 2 weeks of administration of losartan/hydrochlorothiazide and after 3 to 4 months of treatment. The transfer function between beat-to-beat changes in BP and cerebral blood flow velocity was estimated to assess dynamic autoregulation. After 1 to 2 weeks of treatment, BP was …

Effects Of Gender And Hypovolemia On Sympathetic Neural Responses To Orthostatic Stress, Qi Fu, Sarah Witkowski, Kazunobu Okazaki, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

We tested the hypothesis that women have blunted sympathetic neural responses to orthostatic stress compared with men, which may be elicited under hypovolemic conditions. Muscle sympathetic nerve activity (MSNA) and hemodynamics were measured in eight healthy young women and seven men in supine position and during 6 min of 60° head-up tilt (HUT) under normovolemic and hypovolemic conditions (randomly), with ∼4-wk interval. Acute hypovolemia was produced by diuretic (furosemide) administration ∼2 h before testing. Orthostatic tolerance was determined by progressive lower body negative pressure to presyncope. We found that furosemide produced an ∼13% reduction in plasma volume, causing a similar …

Persistent Sympathetic Activation During Chronic Antihypertensive Therapy, Qi Fu, Rong Zhang, Sarah Witkowski, Armin Arbab-Zadeh, Anand Prasad, Kazunobu Okazaki, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

Previous studies have demonstrated that antihypertensive treatment resets baroreflex control of heart rate (HR) and increases cardiac vagal baroreflex sensitivity. However, it is uncertain whether baroreflex control of muscle sympathetic nerve activity (MSNA) also resets after treatment. We tested the hypothesis that chronic antihypertensive therapy alters baroreflex regulation of MSNA in patients with untreated moderate hypertension. Seven newly diagnosed patients with systolic blood pressure (BP) of 159 5 mm Hg (mean SE) and diastolic BP of 103 4 mm Hg were studied before and after 1 to 2 weeks ´ and 3 months (chronic) of antihypertensive treatment with losartan– hydrochlorothiazide …

Inhibition Of Nitric Oxide Inhibition Of Nitric Oxide Synthase Does Not Alter Dynamic Cerebral Autoregulation In Humans, Rong Zhang, Thad E. Wilson, Sarah Witkowski, Jian Cui, Craig G. Crandall, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

The aim of this study was to determine whether inhibition of nitric oxide synthase (NOS) alters dynamic cerebral autoregulation in humans. Beat-to-beat blood pressure (BP) and cerebral blood flow (CBF) velocity (transcranial Doppler) were measured in eight healthy subjects in the supine position and during 60° head-up tilt (HUT). NOS was inhibited by intravenous N G-monomethyl-L-arginine (L-NMMA) infusion. Dynamic cerebral autoregulation was quantified by transfer function analysis of beat-to-beat changes in BP and CBF velocity. Pressor effects of L-NMMA on cerebral hemodynamics were compared with those of phenylephrine infusion. In the supine position, L-NMMA increased mean BP from 83 ± …

Vasoconstrictor Reserve And Sympathetic Neural Control Of Orthostasis, Qi Fu, Sarah Witkowski, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

Background—We tested the hypothesis that individual variability in orthostatic tolerance is dependent on the degree of neural and vasomotor reserve available for vasoconstriction.

Methods and Results—Muscle sympathetic nerve activity (MSNA) and hemodynamics were measured in 12 healthy young volunteers during 60° head-up tilt (HUT), followed by a cold pressor test (CPT) in HUT. Orthostatic tolerance was determined by progressive lower-body negative pressure (LBNP) to presyncope. The same protocols were performed randomly in normovolemic and hypovolemic conditions. We found that mean arterial pressure increased and stroke volume decreased, whereas heart rate (HR), MSNA, and total peripheral resistance (TPR) increased during HUT …

Nitric Oxide Synthase Inhibition Does Not Affect Regulation Of Muscle Sympathetic Nerve Activity During Head-Up Tilt, Jian Cui, Rong Zhang, Thad E. Wilson, Sarah Witkowski, Craig G. Crandall, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

To test the hypothesis that systemic inhibition of nitric oxide (NO) synthase does not alter the regulation of sympathetic outflow during head-up tilt in humans, in eight healthy subjects NO synthase was blocked by intravenous infusion of NG-monomethyl-L-arginine (L-NMMA). Blood pressure, heart rate, cardiac output, total peripheral resistance (TPR), and muscle sympathetic nerve activity (MSNA) were recorded in the supine position and during 60° head-up tilt. In the supine position, infusion of L-NMMA increased blood pressure, via increased TPR, and inhibited MSNA. However, the increase in MSNA evoked by head-up tilt during L-NMMA infusion (change in burst rate: 24 ± …

Determinants Of Erythropoietin Release In Response To Short-Term Hypobaric Hypoxia, Ri Li Ge, S. Witkowski, Y. Zhang, C. Alfrey, M. Sivieri, T. Karlsen, G. K. Resaland, M. Harber, J. Stray-Gundersen, B. D. Levine

Exercise and Sport Studies: Faculty Publications

We measured blood erythropoietin (EPO) concentration, arterial O2 saturation (SaO2), and urine PO2 in 48 subjects (32 men and 16 women) at sea level and after 6 and 24 h at simulated altitudes of 1,780, 2,085, 2,454, and 2,800 m. Renal blood flow (Doppler) and Hb were determined at sea level and after 6 h at each altitude (n = 24) to calculate renal O2 delivery. EPO increased significantly after 6 h at all altitudes and continued to increase after 24 h at 2,454 and 2,800 m, although not at 1,780 or 2,085 m. The increase in EPO varied markedly …

Skin Cooling Maintains Cerebral Blood Ffow Velocity And Orthostatic Tolerance During Tilting In Heated Humans, Thad E. Wilson, Jian Cui, Rong Zhang, Sarah Witkowski, Craig G. Crandall

Exercise and Sport Studies: Faculty Publications

Orthostatic tolerance is reduced in the heat-stressed human. The purpose of this project was to identify whether skin-surface cooling improves orthostatic tolerance. Nine subjects were exposed to 10 min of 60° head-up tilting in each of four conditions: normothermia (NT-tilt), heat stress (HT-tilt), normothermia plus skin-surface cooling 1 min before and throughout tilting (NT-tiltcool), and heat stress plus skin-surface cooling 1 min before and throughout tilting (HT-tiltcool). Heating and cooling were accomplished by perfusing 46 and 15°C water, respectively, though a tube-lined suit worn by each subject. During HT-tilt, four of nine subjects developed presyncopal symptoms resulting in the termination …