Heidi Y. Perkins

Rice University, Houston, Texas, United States

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Publications (10)29.9 Total impact

  • [Show abstract] [Hide abstract] ABSTRACT: Previous research shows that physical activity (PA) can improve physical functioning and quality of life in cancer patients and survivors. The current recommendations for PA in healthy individuals and cancer survivors is 150-250 min/week in order to prevent weight gain and receive other health benefits. PA interventions are not always effective for all participants, and most research examining for whom these interventions are most effective have mainly looked at moderating factors such as age, gender, and psychological factors. Few studies have attempted to examine unmeasured heterogeneity in PA outcomes. This study attempts to model this heterogeneity using growth mixture modeling (GMM) and predict different PA trajectories using baseline measures of somatic sensations, modeling, social support, and self-efficacy. Participants included 98 women with Stage I, II, or IIIa endometrial cancer who were at least 6 months post-treatment and had no evidence of disease. Longitudinal data were collected over a 6 month time period at six different time points using ecological momentary assessment data for at home self-report measures of antecedents of self-efficacy, self-efficacy, and PA as well as accelerometry data for PA. After baseline assessment, participants were given individually tailored PA recommendations; engaging in moderate-intensity exercise for 30 minutes a day, 5 days a week. Between measurement time points, participants received telephone counseling which reviewed exercise goals and barriers, and provided brief teaching of behavioral and cognitive skills to support their PA behaviors. Data were analyzed using GMM to determine if there are different PA trajectories and logistic regression to predict class membership of the PA trajectories using baseline measures of somatic sensations, modeling, social support, and self-efficacy. Results from the GMM of PA suggest participants can be classified into one of two PA trajectories; a high PA trajectory, where participants engage in a high level of PA that is stable over time and a rising PA trajectory, where participants engage in low levels of PA at baseline and increase over time. Logistic regression predicting these trajectories shows those with high levels of social support at baseline are over six times more likely to be part of the high PA trajectory. These results suggest endometrial cancer survivors with low levels of social support are less likely to engage in PA at baseline, and may be most likely to benefit from an intervention that provides support through telephone coaching. Results also indicate certain participants are already engaging in high levels of PA and were unaffected by the intervention. Future studies should see if changes over time in social support lead to increases in PA.
    No preview · Conference Paper · May 2014
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    [Show abstract] [Hide abstract] ABSTRACT: Objective: This study evaluated whether social-cognitive theory (SCT) variables, as measured by questionnaire and ecological momentary assessment (EMA), predicted exercise in endometrial cancer survivors. Method: One hundred posttreatment endometrial cancer survivors received a 6-month home-based exercise intervention. EMAs were conducted by using hand-held computers for 10- to 12-day periods every 2 months. Participants rated morning self-efficacy and positive and negative outcome expectations by using the computer, recorded exercise information in real time and at night, and wore accelerometers. At the midpoint of each assessment period, participants completed SCT questionnaires. Using linear mixed-effects models, the authors tested whether morning SCT variables predicted minutes of exercise that day (Question 1) and whether exercise minutes at time point Tj could be predicted by questionnaire measures of SCT variables from time point Tj-1 (Question 2). Results: Morning self-efficacy significantly predicted that day's exercise minutes (p < .0001). Morning positive outcome expectations were also associated with exercise minutes (p = .0003), but the relationship was attenuated when self-efficacy was included in the model (p = .4032). Morning negative outcome expectations were not associated with exercise minutes. Of the questionnaire measures of SCT variables, only exercise self-efficacy predicted exercise at the next time point (p = .003). Conclusions: The consistency of the relationship between self-efficacy and exercise minutes over short (same day) and longer (Tj to Tj-1) time periods provides support for a causal relationship. The strength of the relationship between morning self-efficacy and exercise minutes suggest that real-time interventions that target daily variation in self-efficacy may benefit endometrial cancer survivors' exercise adherence.
    Full-text · Article · Feb 2013 · Health Psychology
  • No preview · Article · May 2011 · Medicine & Science in Sports & Exercise
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    [Show abstract] [Hide abstract] ABSTRACT: Physical activity has been shown to benefit cancer survivors' physical functioning, emotional well-being, and symptoms. Physical activity may be of particular benefit to survivors of endometrial cancer because they are more likely to be obese and sedentary than the general population, as these are risk factors for the disease, and thus experience a number of related co-morbid health problems. However, there is little research systematically studying mechanisms of physical activity adherence in cancer survivor populations. This paper describes the design of the Steps to Health study, which applies a Social Cognitive Theory-based model of endometrial cancer survivors' adoption and maintenance of exercise in the context of an intervention to increase walking or other moderate intensity cardiovascular activity. In Steps to Health we will test the influence of self-efficacy and outcome expectations on adherence to exercise recommendations, as well as studying the determinants of self-efficacy. Endometrial cancer survivors who are at least 6 months post-treatment are provided with an intervention involving print materials and telephone counseling, and complete assessments of fitness, activity, self-efficacy and outcome expectations, and determinants of self-efficacy every two months for a six month period. In addition to testing an innovative model, the Steps to Health study employs multiple assessment methods, including ecological momentary assessment, implicit tests of cognitive variables, and ambulatory monitoring of physical activity. The study results can be used to develop more effective interventions for increasing physical activity in sedentary cancer survivors by taking into account the full complement of sources of self-efficacy information and outcome expectations.
    Full-text · Article · Jan 2011 · Psychology of Sport and Exercise
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    Full-text · Article · Mar 2010 · Cancer Epidemiology Biomarkers & Prevention
  • [Show abstract] [Hide abstract] ABSTRACT: Studies have shown that expectations about exercise outcomes are associated with exercise behavior. Outcome expectations can be assessed by self-report questionnaires, but a new method-the expectancy accessibility task-may convey unique information about outcome expectations that is less subject to respondent biases. This method involves measuring the reaction time to endorse or reject an outcome We examined the relationship of self-reported outcome expectations and expectancy accessibility tasks in a pilot study of sedentary endometrial cancer survivors (N = 20). After measuring outcome expectations and expectancy accessibility, participants were given an exercise program and asked to monitor exercise for 7 days using diaries and accelerometers. Analyses revealed no relationship between outcome expectation scores and exercise, but shorter response times to endorse positive exercise outcomes was related to more exercise in the next week (p = .02).
    No preview · Article · Dec 2009 · Journal of Sport & Exercise Psychology
  • No preview · Article · May 2009 · Medicine & Science in Sports & Exercise
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    [Show abstract] [Hide abstract] ABSTRACT: The physical and psychological benefits of exercise for cancer survivors are well documented. Researchers have examined self-efficacy (SE) as a target for promoting exercise; however, the predictors of SE, including treatment factors and comorbidities, have not been examined extensively. The purpose of this cross-sectional analysis was to examine how variables related to cancer and cancer treatment, comorbid health problems, health-related quality of life (QOL), and depression relate to SE for physical activity in cancer survivors. This secondary analysis examined treatment factors, comorbidity, and QOL data from 148 breast cancer and 134 prostate cancer survivors who had participated in studies examining exercise and QOL. A predictive regression model was developed by testing each variable individually with SE and including the variables that had a significance of <or=0.2 in a multivariate regression model. For the breast cancer population, vitality (B=0.23, p=0.02), bodily pain (B=0.16, p=0.07), and mental health (B=0.15, p=0.01) were associated with SE for physical activity. For the prostate cancer survivors, education, (B=-0.20, p=0.036) vitality (B=0.26, p=0.01), and bodily pain (B=0.13, p=0.182) remained in the model. Treatment factors and comorbidities were not associated with SE for physical activity, but health-related QOL factors of vitality and bodily pain were associated with SE. Thus, subjective measures of well-being are important factors to consider when developing targeted interventions to increase physical activity in cancer survivors.
    Full-text · Article · Apr 2009 · Psycho-Oncology
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    [Show abstract] [Hide abstract] ABSTRACT: Many breast cancer survivors experience long term sequelae, including fatigue, decreased physical functioning, pain, and psychological distress. Physical activity can ameliorate these problems, but there is little research on how activity should be performed to be most beneficial. This study explores how dimensions of physical activity (total energy expenditure, frequency, and duration) are associated with symptoms among breast cancer survivors. We conducted a secondary analysis of data on physical activity behavior and symptoms in a cross-sectional study (n = 148) of breast cancer survivors who were off treatment and had been diagnosed within the past 5 years. Multivariate analyses showed that total energy expenditure was associated with better general health (p = 0.006) and fewer depressive symptoms (p = 0.014), while frequency of activity was linearly related to physical functioning (p = 0.047), pain (0.057), general health (p < 0.001), and depressive symptoms (p < 0.001). Duration was related to physical functioning, pain, and general health, but the worst outcomes were reported by the participants with the shortest and longest duration of activity (quadratic trend p values = 0.002, 0.003, 0.008, respectively). Greater total energy expenditure, higher physical activity frequency, and moderate duration were associated with better outcomes for most symptoms, although there was no relationship between any of the dimensions of physical activity and fatigue. The association of better outcomes with higher energy expenditure, higher frequency of activity, and moderate duration indicates that increasing activity through multiple short bouts may be the most beneficial for breast cancer survivors. However, randomized studies are needed to confirm this finding.
    Full-text · Article · Nov 2008 · Journal of Cancer Survivorship
  • No preview · Article · May 2008 · Medicine & Science in Sports & Exercise