Papers by Kelley Strohacker
Health Psychology, 2020
OBJECTIVE To pilot test two low-cost and thus financially sustainable incentive programs to promo... more OBJECTIVE To pilot test two low-cost and thus financially sustainable incentive programs to promote physical activity (PA) among low-active adults in a community setting. METHOD In a three-arm randomized controlled trial the effects of small monetary incentives (cash incentives $1/day; n = 25) were compared to charitable donations (donation $1/day; n = 25) and a control group (n = 25) on PA behavior over the course of 12 months in insufficiently active, otherwise healthy adults. Incentives were based on attendance at a local YMCA. Electronic swipe card data from the YMCA was the primary outcome, with self-reported minutes of PA as a secondary outcome. RESULTS Quantile regression models showed promising effects of treatment allocation on the primary outcome (attendance) adjusted for age and employment. There was a difference between cash incentives and control conditions such that median attendance in the cash incentives condition was 19.24 visits more over 12 months (b = 19.24; SE = 8.26, 95% CI [2.75, 35.72]). There was a similar though only marginally significant trend for the donation condition showing that participants in the donation condition made 11.88 additional visits to the YMCA over 12 months relative to the control condition (b = 11.88, SE = 8.41,95% CI [-0.91, 28.67]). There was a significant correlation between objectively verified YMCA attendance and self-reported moderate-to-vigorous PA at the YMCA (ρ = 0.587) over 12 months. CONCLUSIONS These promising findings provide early support for small monetary incentives and charitable donations for promoting PA in community settings. Further research on the efficacy of using financially sustainable incentive programs, including charitable donations, for PA through community organizations (e.g., YMCAs) seems warranted. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
Medicine & Science in Sports & Exercise, 2017
p<0.05), with no differences between FavTV and NatTV (p=0.132). Part 2: Despite this difference i... more p<0.05), with no differences between FavTV and NatTV (p=0.132). Part 2: Despite this difference in preference for exercise, there was no significant difference in treadmill walking time (FavTV vs. NoTV; 50.0±2.6 vs. 44.7±3.2 minutes, respectively; p=0.102). CONCLUSIONS: This study provides empirical evidence that inactive individuals prefer walking with television viewing versus with no television. Further research is needed to determine if active television viewing can translate to observable changes in exercise behaviors.
Medicine and science in sports and exercise, 2016
We propose that enjoyment is an important factor in the adoption and long-term maintenance of exe... more We propose that enjoyment is an important factor in the adoption and long-term maintenance of exercise. Television (TV) viewing is believed to be a highly enjoyed leisure-time activity, combining it with exercise may make for a more enjoyable exercise experience. The objective of this study was to examine the effects of television (TV) viewing on psychological and physiological variables during a moderate-intensity exercise bout. Twenty-eight insufficiently active (<150 minutes per week of moderate intensity PA and/or 75 minutes of vigorous PA) adults (Age: M = 47.4 ± 7.6 years) participated in this study. Each participant performed three separate 30-minute walking bouts on a motorized treadmill. During each bout, participants watched a program they selected (30-minute scripted show) (self-selected TV condition), a British Broadcasting Corporation (BBC) nature program (standardized TV condition), or no TV program (no TV condition). Participants were unable to select the nature program as their self-selected program, as it was not a 30-minute scripted program. A Polar Heart Rate (HR) monitor and validated surveys on affect and enjoyment were used. Participants reported greater enjoyment of exercise for both self-selected and standardized TV conditions (97.1 ± 15.2 and 92.7 ± 15.2), compared to the No TV condition (77.5 ± 13.4, p < 0.001). The two TV conditions resulted in similar levels of focus on TV viewing (self-selected TV: 81.2 ± 19.7; standardized TV: 79.1 ± 14.2, p > 0.05) and dissociation from walking (self-selected TV: 38.1 ± 6.7 and standardized TV: 33.2 ± 3.9); they also resulted in more dissociation than the no TV condition (TV: 72.6 ± 5.6, p = 0.002). The findings indicate that TV viewing, regardless of whether the programming is self-selected or standardized, associates with greater enjoyment of exercise.
Journal of sport & exercise psychology, 2015
This study examined whether inactive, overweight/obese women experience consistent affective resp... more This study examined whether inactive, overweight/obese women experience consistent affective responses to moderate-intensity exercise. Twenty-eight women participated in 3 identical (same treadmill grade and speed within a subject) 30-min exercise sessions. The Feeling Scale (FS), Positive and Negative Affect Schedule and Subjective Exercise Experience Scale were administered pre- and postexercise and FS was also administered every 5 min during exercise. All measures exhibited less than optimal agreement in pre-to-postexercise change within an individual across the 3 sessions (ICCs = 0.02-0.60), even after controlling for within-subject variations in heart rate. Only FS exhibited "good" consistency when controlling for preexercise values (ICC = 0.72). However, the mean FS score during exercise was highly consistent within an individual (ICC = 0.83). Thus, an…
Int J Obes (Lond), 2013
Numerous laboratory studies involving both animal and human models indicate that weight loss indu... more Numerous laboratory studies involving both animal and human models indicate that weight loss induces changes in leptin, ghrelin and insulin sensitivity, which work to promote weight regain. It is unclear, however, whether these biological changes serve as a biomarker for predicting weight regain in free-living humans in which biological, behavioral and environmental factors are likely at play. We identified 12 studies published between January 1995 and December 2011 that reported changes in leptin, ghrelin or insulin during intentional weight loss with a follow-up period to assess regain. Two of the nine studies examining leptin suggested that larger decreases were associated with greater regain, three studies found the opposite (smaller decreases were associated with greater regain), whereas four studies found no significant relationship; none of the studies supported the hypothesis that increases in ghrelin during weight loss were associated with regain. One study suggested that improvements in insulin resistance were associated with weight gain, but five subsequent studies reported no association. Changes in leptin, ghrelin or insulin sensitivity, taken alone, are not sufficient to predict weight regain following weight loss in free-living humans. In future studies, it is important to include a combination of physiological, behavioral and environmental variables in order to identify subgroups at greatest risk of weight regain.
Pediatrics, 2012
BACKGROUND AND OBJECTIVE: Obesity is an independent risk factor for chronic disease. The prevalen... more BACKGROUND AND OBJECTIVE: Obesity is an independent risk factor for chronic disease. The prevalence of obesity is especially high among Mexican American children. Peripheral blood monocytes are altered with obesity contributing to elevated systemic inflammation and increased risk of chronic disease. In addition, obesity alters the circulating levels of cytokines/chemokines that influence monocyte behavior. The study objective was to investigate alterations in blood monocytes and plasma cytokines/chemokine levels among healthy weight (standardized BMI [zBMI] ≤85th percentile; n = 66), overweight (zBMI 85th–95th percentile; n = 23), and obese (zBMI ≥95th percentile; n = 39) Mexican American children. METHODS: Blood samples were analyzed for total and subset monocyte concentration via flow cytometry. Serum monocyte chemoattractant protein-1 (MCP-1), fractalkine, interleukin-8, and tumor necrosis factor α (TNF-α) were measured by using a Milliplex MagPix assay. Serum cholesterol, high-d...
Medicine & Science in Sports & Exercise, 2009
Medicine & Science in Sports & Exercise, 2009
Maternal & Child Nutrition, 2012
School‐based interventions are an effective way to treat childhood obesity. The purpose of the pr... more School‐based interventions are an effective way to treat childhood obesity. The purpose of the present study was to biologically validate an established school‐based intervention designed to reduce standardised body mass index (zBMI) over a period of 12 months. This intervention focused on a subset of Mexican‐American children who were participating in a larger clinical weight loss study. Plasma samples were analysed from self‐identified Mexican‐American children (12–14 years) who were randomised to either a school‐based intervention (IN, n = 152) or self‐help control (CN, n = 69). Treatment was 4 days week−1 of exercise (45 min day−1) and 1 day week−1 of nutritional counselling for 6 months. Fasting (>8 h) blood samples were collected at baseline, 6 months (end of active intervention) and 12 months (6 months after the end of the active intervention). Plasma resistin, adiponectin and leptin concentration were measured using a multiplex assay. Separate linear mixed models and a P ...
Life Sciences, 2011
Aim-Our aim is to investigate the molecular mechanism of regulation of gene expression of drug me... more Aim-Our aim is to investigate the molecular mechanism of regulation of gene expression of drug metabolizing enzymes (DMEs) and transporters in diet-induced obesity. Main methods-Adult male CD1 mice were fed diet containing 60% kcal fat (HFD) or 10% kcal fat (LFD) for 14 weeks. RNA levels of hepatic DMEs, transporters and their regulatory nuclear receptors (NRs) were analyzed by real-time PCR. Activation of cell-signaling components (JNK and NF-κB) and pro-inflammatory cytokines (IL-1β, IL-6 and TNFα) were measured in the liver. Finally, the pharmacodynamics of drugs metabolized by DMEs was measured to determine the clinical relevance of our findings. Key findings-RNA levels of the hepatic phase I (Cyp3a11, Cyp2b10, Cyp2a4) and phase II (Ugt1a1, Sult1a1, Sultn) enzymes were reduced ~30-60% in HFD compared to LFD mice. RNA levels of Cyp2e1, Cyp1a2 and the drug transporters, multidrug resistance proteins, (Mrp)2, Mrp3 and multidrug resistant gene (Mdr)1b were unaltered in HFD mice. Gene expression of the NRs, PXR and CAR and nuclear protein levels of RXRα was reduced in HFD mice. Cytokines, JNK and NF-κB were induced in HFD mice. Thus reduction in hepatic gene expression in obesity may be modulated by cross-talk between NRs and inflammation-induced cell-signaling. Sleep time of Midazolam (Cyp3a substrate) was prolonged in HFD mice, while Zoxazolamine (Cyp1a2 and Cyp2e1 substrate)-induced sleep time was unaltered. Significance-This study demonstrates that gene-specific reductions in DMEs can affect specific drugs metabolized by these enzymes, thus providing a rationale to monitor the effectiveness of drug therapy in obese individuals.
Applied Physiology, Nutrition, and Metabolism, 2012
High-fat meals promote transient increases in proatherogenic factors, implicating the postprandia... more High-fat meals promote transient increases in proatherogenic factors, implicating the postprandial state in cardiovascular disease (CVD) progression. Although low-grade inflammation is associated with CVD, little research has assessed postprandial inflammation. Because of its anti-inflammatory properties, premeal exercise may counteract postprandial inflammation. The purpose of this study was to determine postprandial alterations in monocytes and circulating markers of endothelial stress and inflammation following a high-fat meal in young adults with or without premeal cycle exercise. Each subject completed two trials and was randomized to rest or cycle at a moderate intensity prior to eating a high-fat meal. Flow cytometry was used to assess monocyte cell surface receptor expression and concentration of endothelial microparticles (EMP). Plasma cytokines were assessed using Luminex MagPix. Statistical analysis was completed using separate linear mixed models analyses with first-orde...
Frontiers in Sports and Active Living, 2021
Recent research in exercise prescription and periodization has emphasized the importance of subje... more Recent research in exercise prescription and periodization has emphasized the importance of subjective experience, both in medium- and long-term monitoring, but also in the acute experience. Emerging evidence also highlights an important role of subjective readiness (pre-exercise mental and physical states) in determining how exercise is experienced, and in acutely modifying the prescribed exercise intensity. The concept of “readiness-to-exercise” shows promise in enabling and informing this acute decision-making to optimize the experiences and outcomes of exercise. While subjective experiences can be effectively assessed using psychometric scales and instruments, these are often developed and deployed using cross-sectional samples, with resulting structures that reflect a normative pattern (nomothetic). These patterns may fail to reflect individual differences in sensitivity, experience and saliency (idiographic). We conducted this research with the primary aim of comparing the nom...
Due to high interaction rates, smart devices are being utilized for mobile health (mHealth) inter... more Due to high interaction rates, smart devices are being utilized for mobile health (mHealth) interventions. Multimedia capabilities may be leveraged to improve mHealth exercise interventions. Our purpose was to explore individuals' perceptions of multimedia exercise prompts tailored to their immediate mental/physical states. Using electronic surveys, respondents provided in-the-moment ratings of emotional state, energy, fatigue, physical discomfort, and thirst, with higher scores reflecting a higher "readiness to exercise" (i.e., if a person is currently in a pleasant mood with high energy and low discomfort, he/she is likely to have a greater capacity for a larger dose of exercise). They were then provided with an exercise prompt designed to match their readiness to exercise, demonstrated via text and graphic interchange format (GIF) showing a research member completing the recommended activity. Survey data regarding GIF quality, self-efficacy, and methodological feedb...
Translational Journal of the ACSM, 2019
Contemporary clinical trials, Jan 31, 2018
Regular physical activity (PA) enhances weight-loss and reduces risk of chronic disease. However,... more Regular physical activity (PA) enhances weight-loss and reduces risk of chronic disease. However, as few as 10% of U.S. adults engage in regular PA. Incentive programs to promote PA have shown some promise, but have typically used incentives that are too large to sustain over time and have not demonstrated habit formation or been tested in community settings. This report presents the rationale and design of a randomized pilot study testing the feasibility and preliminary efficacy of small monetary incentives for PA (n=25) versus charitable donations in the same amount (n=25) versus control (n=25) over 12months among 75 low-active but otherwise healthy adults at a local YMCA. Incentives are based on YMCA attendance, which is verified by electronic swipe card data and is the primary study outcome, with self-reported minutes/week of PA assessed as a secondary outcome. Incentives are intentionally small enough-$1/session, maximum of $5/week-such that they could be indefinitely sustained...
International journal of exercise science
Excessive weight gain increases systemic inflammation resulting in increased disease risk. Toll-l... more Excessive weight gain increases systemic inflammation resulting in increased disease risk. Toll-like receptor 4 (TLR4) reportedly mediates increases in inflammation; however, its role in obesity-induced inflammation has not been fully evaluated. The purpose of this study was to determine the longitudinal effect of diet-induced weight gain on blood monocyte concentration and cell-surface TLR4 expression. Male CD-1 mice were randomly assigned to high-fat (HF, n = 12) or low-fat (LF, n = 13) groups. Non-lethal, saphenous vein blood samples were collected at 0, 4, 8 and 12 weeks of treatment. Three-color flow cytometry was used to measure monocyte (CD11b(+)/CD14(+)) concentration and TLR4 cell-surface expression. Data were analyzed with a repeated measures ANOVA; significance was set at P<0.05. Body weight at week 12 was 21% greater in HF than LF (P<0.05). At week 12 HF had 155% more monocytes (P<0.05) with 24% less TLR4 than LF; Monocyte concentration and body weight at week 1...
American journal of health behavior, 2015
Research has demonstrated that health outcomes are significantly improved with the application of... more Research has demonstrated that health outcomes are significantly improved with the application of financial incentives. However, relatively larger incentives are not typically sustainable and removal of incentives tends to result in attrition of behavior. The feasibility of using relatively smaller incentives to improve physical activity is unclear. The aim of the present study is to determine whether small financial incentives (maximum $5.00 per week) can improve exercise-related energy expenditure of inactive individuals. Twenty-two university students (20 ±1.6 years old) were randomized into incentive or non-incentive conditions. Exercise-related caloric expenditure was tracked over 10 weeks. The sample size yielded 62% power. The repeated measures ANCOVA, controlling for body mass index, indicated a main effect of condition (F = 5.50, p =.03) with no significant interaction (F = 2.25, p = .06). This pilot study demonstrates initial feasibility in implementing small financial inc...
Background. Monocyte assessment is used in aging research. In humans, reduced expression of toll-... more Background. Monocyte assessment is used in aging research. In humans, reduced expression of toll-like receptors, T-lymphocyte priming receptors and increases in intracellular adhesion molecules on monocytes have been associated with functional decrements, resulting in increased disease risk. While use of mouse models is extensive in aging research, mouse monocyte assessment is rare. We aimed to evaluate differences in cell-surface protein expression in classic (CD115 + /Gr-1 high) and non-classic (CD115 + /Gr-1 low) monocyte subsets of old and young mice. Methods. Venous blood was drawn from 18 old (80-wks) and 18 young CD-1 mice (15-20-wks). Flow cytometry was used to assess subpopulations of CD115 + monocytes for TLR2, TLR4, CD80, CD86, MHC II, CD54 and CD25. Data were analyzed with 2 (age groups) x 2 (monocyte populations) repeated measures ANOVA; significance was set at P<0.05. Results. Old mice had greater proportions of classic monocytes (P<0.05). TLR4 and CD80 was 27% and 37% lower in classic monocytes of old mice (P<0.05). Body weight was not a significant covariate in the analysis. Conclusions. We found that old mice had elevated classic monocyte proportions and with lower expression of TLR4 and CD80. Because similar findings in older adults have been associated with increased risk of cardiovascular disease and infection, we surmise that old mice were also had increased disease risk compared to young mice. These findings support the use of monocyte subset phenotyping in murine models of aging.
Preventive Medicine Reports, 2015
Background. Periodization of exercise is a method typically used in sports training, but the impa... more Background. Periodization of exercise is a method typically used in sports training, but the impact of periodized exercise on health outcomes in untrained adults is unclear. Purpose. This review aims to summarize existing research wherein aerobic or resistance exercise was prescribed to inactive adults using a recognized periodization method. Methods. A search of relevant databases, conducted between January and February of 2014, yielded 21 studies published between 2000 and 2013 that assessed the impact of periodized exercise on health outcomes in untrained participants. Results. Substantial heterogeneity existed between studies, even under the same periodization method. Compared to baseline values or non-training control groups, prescribing periodized resistance or aerobic exercise yielded significant improvements in health outcomes related to traditional and emerging risk factors for cardiovascular disease, low-back and neck/shoulder pain, disease severity, and quality of life, with mixed results for increasing bone mineral density. Conclusions. Although it is premature to conclude that periodized exercise is superior to non-periodized exercise for improving health outcomes, periodization appears to be a feasible means of prescribing exercise to inactive adults within an intervention setting. Further research is necessary to understand the effectiveness of periodizing aerobic exercise, the psychological effects of periodization, and the feasibility of implementing flexible non-linear methods.
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Papers by Kelley Strohacker