Effects of mindful physical activity on perceived exercise exertion and other physiological and psychological responses: results from a within-subjects, counter-balanced study.

Background: Most adults are insufficiently active. Mindfulness training may increase moderate to vigorous physical activity (MVPA) adoption and adherence. However, physiological and psychological factors underlying these effects are not well understood. This study examined the effects of an acute bout of MVPA, mindfulness training, and combined MVPA and mindfulness training on physiological and psychological outcomes. Methods: Healthy adults (N = 29, Mage = 28.6) completed 20-min counterbalanced conditions: (a) mindfulness training (MIND); (b) moderate intensity walking (PA), and (c) moderate intensity walking while listening to MVPA-specific guided mindfulness training (PAMIND). Heart rate (HR), Rating of Perceived Exertion (RPE), Feeling Scale (FS) and Blood Pressure (BP) were measured at rest, at regular intervals during each condition, and post-condition. Mindfulness, state anxiety, and self-efficacy were assessed pre- and post-condition. Results: Average and peak HR, systolic BP (SBP), and RPE were significantly higher, and average and peak FS were significantly lower during the PA and PAMIND conditions compared to MIND (p < 0.001). Average RPE was significantly higher for PA compared to PAMIND (p < 0.001). Heart rate, feeling scale, body and mental events mindfulness, and self-efficacy for walking increased from pre to post (all p's < 0.001) for all conditions. Time by condition interactions were significant for change in heart rate, mental events mindfulness, and state anxiety from pre- to post-condition. Conclusion: The physiological response to MVPA and PAMIND were similar. However, RPE was rated lower in the PAMIND condition, which could have implications for MVPA adoption and maintenance. Future work should further explore RPE combining MVPA and mindfulness training.

Effect of the Fit2Thrive Intervention on Patient-reported Outcomes in Breast Cancer Survivors: A Randomized Full Factorial Trial.

BACKGROUND: Moderate to vigorous physical activity (MVPA) interventions improve patient-reported outcomes (PROs) of physical and psychological health among breast cancer survivors (BCS); however, the effects of specific intervention components on PROs are unknown. PURPOSE: To use the Multiphase Optimization Strategy (MOST) to examine overall effects of the Fit2Thrive MVPA promotion intervention on PROs in BCS and explore whether there are intervention component-specific effects on PROs. METHODS: Physically inactive BCS [n = 269; Mage = 52.5 (SD = 9.9)] received a core intervention (Fitbit + Fit2Thrive smartphone app) and were randomly assigned to one of 32 conditions in a full factorial experiment of five components ("on" vs. "off"): (i) support calls, (ii) deluxe app, (iii) text messages, (iv) online gym, and (v) buddy. Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaires assessed anxiety, depression, fatigue, physical functioning, sleep disturbance and sleep-related impairment at baseline, post-intervention (12-week), and 24-week follow-up. Main effects for all components at each time point were examined using an intention to treat mixed-effects model. RESULTS: All PROMIS measures except sleep disturbance significantly improved (p's < .008 for all) from baseline to 12-weeks. Effects were maintained at 24-weeks. The "on" level of each component did not result in significantly greater improvements on any PROMIS measure compared to the "off" level. CONCLUSIONS: Participation in Fit2Thrive was associated with improved PROs in BCS, but improvements did not differ for "on" vs. "off" levels for any component tested. The low-resource Fit2Thrive core intervention is a potential strategy to improve PROs among BCS. Future studies should test the core in an RCT and examine various intervention component effects in BCS with clinically elevated PROs.

Longitudinal Sedentary Time and Symptoms in Breast Cancer Patients during Chemotherapy Using Ecological Momentary Assessment.

PURPOSE: To examine the relationship between daily fluctuations in symptoms and sedentary behavior (SB) during chemotherapy (CT) for breast cancer. METHODS: Breast cancer patients ( N = 68, M age = 48.5 ± 10.4 yr) undergoing CT wore an activity monitor on their hip to assess daily SB and completed prompts assessing symptoms (affect, anxiety, depression, fatigue, pain, and physical and cognitive functioning) for 10 consecutive days (3 d pre-CT, day of, and 6 d post-CT) at the beginning, middle and end cycles of CT. Mixed models assessed the bidirectional between-person (BP) and within-person (WP) associations of current day symptoms with minutes of SB measured on 1) the same day and 2) the next day, controlling for relevant covariates. RESULTS: Within person same-day results revealed a significant association between affect, anxiety, fatigue, physical functioning, pain, and cognitive functioning and same-day SB. Worse than average symptom ratings on a given day were associated with more SB that day. There was a significant WP relationship between previous-day anxiety, depression, and physical function and next-day SB (i.e., worse than average symptom ratings the previous day were associated with more SB the next day). Within person same-day results revealed a significant association between same-day SB and affect, anxiety, fatigue, pain, physical functioning, and cognitive functioning. The WP relationships were significant for previous-day SB and next-day affect and pain (i.e., higher than average SB associated with lower ratings). Relationships persisted when controlling for moderate-to-vigorous physical activity. There were no significant BP results. CONCLUSIONS: Higher symptom ratings were associated with increased SB and higher SB was associated with worse symptoms. Future work should identify SB reduction intervention approaches tailoring to daily symptom burden during CT for breast cancer.

Using ecological momentary assessment to understand associations between daily physical activity and symptoms in breast cancer patients undergoing chemotherapy.

PURPOSE: Understanding real-time relationships between physical activity (PA) and symptoms during chemotherapy (CT) could have important implications for intervention. This study used ecological momentary assessment to examine the relationship between objective PA and symptoms during CT. METHODS: Breast cancers patients (n = 67; Mage = 48.6 (SD = 10.3)) participated in data collection at three time points during CT: beginning, middle, and end. At each time point, participants answered four prompts assessing symptoms and wore an accelerometer for 10 days (3 days pre-CT, day of CT, and 6 days post-CT). Multilevel linear regression models examined the between- and within-person associations between moderate to vigorous (MVPA) and light-intensity physical activity (LPA) and same and next-day symptom ratings controlling for covariates. RESULTS: On days when individuals engaged in more LPA or MVPA, separately, they reported improved affect, anxiety, fatigue, physical functioning (walking and activities of daily living), pain, and cognition that day (p < 0.001 for all). Findings were consistent for next-day symptom ratings with the exception that only previous day LPA was related to next-day fatigue and neither LPA nor MVPA were related to next-day cognition (p < 0.001 for all). No between-person effects were found. CONCLUSIONS: Within person higher than usual PA on a given day, regardless of intensity, is associated with improved symptoms ratings on the current and next day. IMPLICATIONS FOR CANCER SURVIVORS: Encouraging breast cancer patients undergoing CT to engage in daily PA could help manage CT-associated symptoms.

Social cognitive variables and physical activity during chemotherapy for breast cancer: An intensive longitudinal examination.

OBJECTIVE: Although physical activity is associated with better health outcomes in breast cancer survivors (BCS), activity often declines during cancer treatment. Social cognitive theory (SCT) constructs have been associated with physical activity in post-treatment BCS, but little is known about the relation between these constructs and physical activity during chemotherapy. METHODS: BCS (n = 67; Mage  = 48.6 [SD = 10.3]) undergoing chemotherapy wore accelerometers and completed prompts in the morning and at night assessing same-day and next-day exercise self-efficacy, physical and psychological outcome expectations, and goal-setting for 10 consecutive days (3 days pre-, day of, and 6 days post-chemotherapy dose) at three time points (beginning, middle, and end of chemotherapy). Separate mixed models assessed between- and within-person associations of each of the SCT constructs associations with same- and next-day moderate to vigorous physical activity (MVPA) and light physical activity (LPA), independently. RESULTS: Within-person differences in all SCT variables were statistically significantly related to same-day MVPA (p's < 0.001) and LPA (p's < 0.001). Every one-point increase in SCT construct related to an increase in MVPA ranging from (a) 3.70 (self-efficacy) to 8.02 (physical outcome expectations) minute increase in MVPA and (b) 12.72 (self-efficacy) to 20.38 (physical outcome expectations) increase in LPA that day. No same-day between-person effects nor any next-day effects were significant. CONCLUSION: MVPA and LPA were related to same-day within-person differences in SCT variables. Interventions targeted at increasing or mitigating chemotherapy-related declines in daily within-person changes in SCT constructs could help to increase physical activity among BCS during chemotherapy.

User-centered development of a smartphone application (Fit2Thrive) to promote physical activity in breast cancer survivors.

Increased moderate and vigorous physical activity (MVPA) is associated with better health outcomes in breast cancer survivors; yet, most are insufficiently active. Smartphone applications (apps) to promote MVPA have high scalability potential, but few evidence-based apps exist. The purpose is to describe the testing and usability of Fit2Thrive, a MVPA promotion app for breast cancer survivors. A user-centered, iterative design process was utilized on three independent groups of participants. Two groups of breast cancer survivors (group 1 n = 8; group 2: n = 14) performed app usability field testing by interacting with the app for ≥3 days in a free-living environment. App refinements occurred following each field test. The Post-Study System Usability Questionnaire (PSSUQ) and the User Version Mobile Application Rating Scale (uMARS) assessed app usability and quality on a 7- and 5-point scale, respectively, and women provided qualitative written feedback. A third group (n = 15) rated potential app notification content. Quantitative data were analyzed using descriptive statistics. Qualitative data were analyzed using a directed content analysis. The PSSUQ app usability score (M1= 3.8; SD = 1.4 vs. M2= 3.2; SD = 1.1; lower scores are better) and uMARS app quality score (M1 = 3.4; SD = 1.3 vs. M2= 3.4; SD = 0.6; higher scores are better) appeared to improve in Field Test 2. Group 1 participants identified app "clunkiness," whereas group 2 participants identified issues with error messaging/functionality. Group 3 "liked" 53% of the self-monitoring, 71% of the entry reminder, 60% of the motivational, and 70% of the goal accomplishment notifications. Breast cancer survivors indicated that the Fit2Thrive app was acceptable and participants were able to use the app. Future work will test the efficacy of this app to increase MVPA.

Optimization of a technology-supported physical activity promotion intervention for breast cancer survivors: Results from Fit2Thrive.

BACKGROUND: The benefits of moderate to vigorous physical activity (MVPA) for breast cancer survivors are well established. However, most are insufficiently active. Fit2Thrive used the Multiphase Optimization Strategy methodology to determine the effect of 5 intervention components on MVPA in this population. METHODS: Two hundred sixty-nine participants (mean age, 52.5 years; SD, 9.9 years) received a core intervention (the Fit2Thrive self-monitoring app and Fitbit) and were randomly assigned to 5 intervention components set to on/off in a full factorial experiment: support calls, deluxe app, buddy, online gym, and text messages. The intervention was delivered over 12 weeks with a 12-week follow-up. MVPA was measured via accelerometry at the baseline (T1), at 12 weeks (T2), and at 24 weeks (T3). The main effects and interaction effects at each time point were examined for all components. RESULTS: Trial retention was high: 91.8% had valid accelerometer data at T2 or T3. Across all conditions, there were significant increases in MVPA (+53.6 min/wk; P < .001) and in the proportion of survivors meeting MVPA guidelines (+22.3%; P < .001) at T2 that were maintained but attenuated at T3 (MVPA, +24.6 min/wk; P < .001; meeting guidelines, +12.6%; P < .001). No individual components significantly improved MVPA, although increases were greater for the on level versus the off level for support calls, buddy, and text messages at T2 and T3. CONCLUSIONS: The Fit2Thrive core intervention (the self-monitoring app and Fitbit) is promising for increasing MVPA in breast cancer survivors, but the components provided no additional increases in MVPA. Future research should evaluate the core intervention in a randomized trial and determine what components optimize MVPA behaviors in breast cancer survivors.

Comparing Accelerometer and Self-Reported Treatment Effects in a Technology-Supported Physical Activity Intervention.

BACKGROUND AND AIMS: To estimate and compare the change in moderate-to-vigorous physical activity (MVPA) between an accelerometer and technology-supported physical activity (PA) log across a 3-week PA intervention. METHOD: Participants (N = 204, 77% female, age = 33 ± 11 years, body mass index = 28.2 ± 7.1 kg/m2) were randomized to one of two activity-related intervention arms: (1) increase MVPA intervention or (2) decrease sedentary behavior active control. Participants wore an accelerometer while simultaneously completing a technology-based PA log every day for 5 weeks: a 2-week baseline assessment phase and a 3-week intervention phase. Bivariate linear mixed-effects models and correlations were used to characterize the relationship of MVPA between measurement methods throughout the intervention. Effect sizes were calculated to determine the intervention effect by measurement method. RESULTS: At baseline, PA log MVPA was 28 minutes greater than accelerometer-based minutes of MVPA in the active control group. This difference was 35 minutes (95% CI [23.7, 46.1]) greater at follow-up than at baseline measurement in the MVPA intervention group. In the active control group, there was a significant 16-minute (95% CI [6.0, 26.5]) increase between the two measures from baseline to follow-up. The intervention effect size based on the PA log was 0.27 (95% CI [0.14, 0.39]) and 0.42 (95% CI [0.28, 0.56]) when using the accelerometer. DISCUSSION AND CONCLUSIONS: Our results indicate that PA log MVPA and accelerometer MVPA estimate significantly different minutes per day of MVPA. It is important researchers use caution when comparing MVPA intervention outcomes from different measurement methods.

Daily Physical Activity and Symptom Reporting in Breast Cancer Patients Undergoing Chemotherapy: An Intensive Longitudinal Examination.

BACKGROUND: Increased activity is beneficial during chemotherapy, but treatment-related symptoms may be a barrier. This study examines the relationship between daily fluctuations in symptoms and activity during chemotherapy. METHODS: Women undergoing chemotherapy for breast cancer [n = 67; M age = 48.6 (SD = 10.3)] wore an accelerometer 24 hours/day and received four text prompts/day to rate symptoms for 10 consecutive days at the beginning, middle, and end of chemotherapy. Mixed-effects models were used to examine the between and within-person relationships between symptom ratings on a given day and moderate to vigorous physical activity (MVPA) and light physical activity (LPA) on that day and the following day controlling for relevant covariates and using the Bonferroni correction for multiple comparisons. RESULTS: For MVPA and LPA, within-person associations were statistically significant for same day affect, fatigue, pain, walking, activities of daily living (ADL) physical function, and cognitive function. Previous day anxiety was associated with next day LPA. Every one point worse symptom rating than an individual's overall average was associated with: (i) between 1.49 (pain) and 4.94 (fatigue) minutes less MVPA and between 4.48 (pain) and 24.72 (ADL physical function) minutes less LPA that day, and (ii) 11.28 minutes less LPA the next day. No between-person effects were significant for MVPA or LPA. CONCLUSIONS: Daily within-person variations in symptoms were associated with MVPA and LPA during chemotherapy for breast cancer. IMPACT: Future work should explore relationships between symptoms and activity further and identify whether tailoring to symptoms enhances efficacy of physical activity promotion interventions during chemotherapy.

Individualized Relative-Intensity Physical Activity Accelerometer Cut Points.

PURPOSE: Physical activity (PA) intensity is expressed as either absolute or relative intensity. Absolute intensity refers to the energy required to perform an activity. Relative intensity refers to a level of effort that takes into account how hard an individual is working relative to their maximum capacity. We sought to develop methods for obtaining individualized relative-intensity accelerometer cut points using data from a maximal graded exercise treadmill test (GXT) so that each individual has their own cut point. METHODS: A total of 2363 men and women 38 to 50 yr old from the CARDIA fitness study wore ActiGraph 7164 accelerometers during a maximal GXT and for seven consecutive days in 2005-2006. Using mixed-effects regression models, we regressed accelerometer counts on heart rate as a percentage of maximum (%HRmax) and on RPE. Based on these two models, we obtained a moderate-intensity (%HRmax = 64% or RPE = 12) count cut point that is specific to each participant. We applied these subject-specific cut points to the available CARDIA accelerometer data. RESULTS: Using RPE, the mean moderate-intensity accelerometer cut point was 4004 (SD = 1120) counts per minute. On average, cut points were higher for men (4189 counts per minute) versus women (3865 counts per minute) and were higher for Whites (4088 counts per minute) versus African Americans (3896 counts per minute). Cut points were correlated with body mass index (rho = -0.11) and GXT duration (rho = 0.33). Mean daily minutes of absolute- and relative-intensity moderate to vigorous PA were 34.1 (SD = 31.1) min·d and 9.1 (SD = 18.2) min·d, respectively. RPE cut points were higher than those based on %HRmax. This is likely due to some participants ending the GXT before achieving their HRmax. CONCLUSIONS: Accelerometer-based relative-intensity PA may be a useful measure of intensity relative to maximal capacity.

Preferences for mHealth physical activity interventions during chemotherapy for breast cancer: a qualitative evaluation.

PURPOSE: Physical activity has been shown to decline over the course of chemotherapy in breast cancer survivors; yet it may reduce treatment-related side effects and emerging evidence indicates it may improve disease outcomes. Mobile health (mHealth) interventions may be an effective, scalable strategy to increase physical activity during treatment. However, little is known about breast cancer patients' interests and preferences for these interventions. It is important to understand patients' interests and preferences prior to development of mHealth physical activity interventions to increase their relevance and efficacy. METHODS: Breast cancer survivors (n = 30) participated in a semi-structured phone interview and were asked about barriers and facilitators to physical activity during chemotherapy as well as their preferences on a range of potential mHealth intervention features. Transcribed interviews were coded and key themes were analyzed using an iterative, inductive approach. RESULTS: Five key themes were extracted from the interviews: (1) need for education about physical activity during chemotherapy; (2) treatment side effects inhibit physical activity; (3) a structured, home-based, tech-supported program with in-person elements is most feasible; (4) need for a personalized, highly tailored intervention; and (5) importance of social support from other breast cancer survivors, friends, and family. CONCLUSIONS: Breast cancer survivors are interested in mHealth physical activity interventions during chemotherapy, but preferences for intervention content and delivery varied. Future work should engage patients and survivors in intervention development and testing.

Breast cancer survivors' preferences for social support features in technology-supported physical activity interventions: findings from a mixed methods evaluation.

Incorporating peer and professional social support features into remotely delivered, technology-supported physical activity interventions may increase their effectiveness. However, very little is known about survivors' preferences for potential social features. This study explored breast cancer survivors' preferences for both traditional (e.g., coaching calls and peer support) and innovative (i.e., message boards and competitions) social support features within remotely delivered, technology-supported physical activity interventions. Survivors [N = 96; Mage = 55.8 (SD = 10.2)] self-reported demographic and disease characteristics and physical activity. A subset (n = 28) completed semistructured phone interviews. Transcribed interviews were evaluated using a thematic content analysis approach and consensus review. Following interviews, the full sample self-reported preferences for social features for remotely delivered physical activity interventions via online questionnaires. Questionnaire data were analyzed using descriptive statistics. Four themes emerged from interview data: (a) technology increases social connectedness; (b) interest in professional involvement/support; (c) connecting with similar survivors; and (d) apprehension regarding competitive social features. Quantitative data indicated that most survivors were interested in social features including a coach (77.1 per cent), team (66.7 per cent), and exercise buddy (57.3 per cent). Survivors endorsed sharing their activity data with their team (80.0 per cent) and buddy (76.6 per cent), but opinions were mixed regarding a progress board ranking their activity in relation to other participants' progress. Survivors were interested in using a message board to share strategies to increase activity (74.5 per cent) and motivational comments (73.4 per cent). Social features are of overall interest to breast cancer survivors, yet preferences for specific social support features varied. Engaging survivors in developing and implementing remotely delivered, technology-supported social features may enhance their effectiveness.

Energy Cost of Slow and Normal Gait Speeds in Low and Normally Functioning Adults.

OBJECTIVE: Slow walking speed paired with increased energy cost is a strong predictor for mortality and disability in older adults but has yet to be examined in a heterogeneous sample (ie, age, sex, disease status). The aim of this study was to examine energy cost of slow and normal walking speeds among low- and normal-functioning adults. DESIGN: Adults aged 20-90 yrs were recruited for this study. Participants completed a 10-m functional walk test at a self-selected normal walking speed and were categorized as low functioning or normal functioning based on expected age- and sex-adjusted average gait speed. Participants completed two successive 3-min walking stages, at slower than normal and normal walking speeds, respectively. Gas exchange was measured and energy cost per meter (milliliter per kilogram per meter) was calculated for both walking speeds. RESULTS: Energy cost per meter was higher (P < 0.0001) in the low-functioning group (n = 76; female = 59.21%; mean ± SD age = 61.13 ± 14.68 yrs) during the slower than normal and normal (P < 0.0001) walking speed bouts compared with the normal-functioning group (n = 42; female = 54.76%; mean ± SD age = 51.55 ± 19.51 yrs). CONCLUSIONS: Low-functioning adults rely on greater energy cost per meter of walking at slower and normal speeds. This has implications for total daily energy expenditure in low-functioning, adult populations.

Effects of reallocating sedentary time with physical activity on quality of life indicators in breast cancer survivors.

OBJECTIVES: Physical activity is associated with better quality of life (QOL) among breast cancer survivors. However, it is unknown the extent to which time spent sedentary or replacing this time with active behaviors may affect QOL. Our aim was to determine the effect of substituting time between sedentary and active behaviors on QOL indicators in breast cancer survivors. METHODS: An isotemporal substitution approach was used to examine the associations of reallocating time to sedentary and active behaviors measured by accelerometry with Functional Assessment of Cancer Treatment-Breast (FACT-B; total, physical, social, emotional, functional well-being, and breast cancer-specific concerns) and the Hospital Anxiety and Depression Scale (HADS) scores in a pooled analysis of breast cancer survivors (n = 753; Mage  = 56.9 ± 9.5 y) from two observational studies. RESULTS: Reallocating 30 minutes of sedentary time to 30 minutes of moderate-to-vigorous intensity physical activity (MVPA) was associated with improved FACT-B total (B = 3.0; 95% CI, 0.6-4.5), physical well-being (B = 0.8; 95% CI, 0.33-1.2), and functional well-being (B = 0.6; 95% CI, 0.03-1.2) scores. Reallocating 30 minutes of light activity to 30 minutes of MVPA was associated with improved FACT-B total (B = 2.4; 95% CI, 0.3-6.0) and physical well-being (B = 0.72; 95% CI, 0.27-1.2) scores. There was no significant substitution of time effects on HADS scores. CONCLUSIONS: Substituting sedentary time with MVPA showed the greatest range of effects across QOL indicators. These results can inform intervention development interventions and more comprehensive activity recommendations for breast cancer survivors.

Breast cancer survivors' preferences for mHealth physical activity interventions: findings from a mixed methods study.

PURPOSE: Despite the benefits of physical activity for breast cancer survivors, the majority remain insufficiently active. Mobile health (mHealth) physical activity interventions may be a more scalable strategy to increase activity among survivors. However, little is known about their preferences for mHealth intervention features. This study explored survivors' preferences for these features. METHODS: Survivors (N = 96; Mage = 55.8 (SD = 10.2)) self-reported demographic and disease characteristics, physical activity. A subset (n = 28) completed a semi-structured phone interview. Transcribed interviews were evaluated using a thematic content analysis approach and consensus review. Following interviews, the full sample self-reported interests and preferences for intervention features via online questionnaires. Quantitative data were analyzed using descriptive statistics. RESULTS: Five themes emerged from interview data: (1) importance of relevance to breast cancer survivors; (2) easy to use; (3) integration with wearable activity trackers; (4) provide sense of accomplishment; and (5) variability in desired level of structure and personalization. The highest ranked intervention features were: daily and weekly progress feedback (87.5%), newsfeed (86.6%), activity challenges (81.3%), and scheduling tool (79.2%). Survivors were interested in receiving progress feedback (80.2%) and motivational (78.1%) and reminder (75.0%) messages. CONCLUSIONS: Breast cancer survivors are interested in mHealth physical activity promotion interventions, but preferences varied around themes of relevance, ease of use, and enhancing personal motivation. IMPLICATIONS FOR CANCER SURVIVORS: Engaging survivors in developing and implementing remotely delivered mHealth activity promotion interventions may enhance their effectiveness.

Sedentary behavior after breast cancer: motivational, demographic, disease, and health status correlates of sitting time in breast cancer survivors.

PURPOSE: Sedentary behavior is associated with poor health outcomes including obesity, lower quality of life, and mortality in breast cancer survivors. This study sought to identify motivational, demographic, and disease characteristics of breast cancer survivors who engage in greater amounts of sedentary behavior. METHODS: Multivariate linear regression models estimated associations between demographic, disease, and health characteristics with reported sitting in breast cancer survivors (n = 279; Mage = 60.7 (± 9.7) years). Regression models estimated associations between motivational factors and reported sitting adjusted for demographic and disease and health covariates. RESULTS: Working at least part-time and marital status were associated various sitting domains including weekday and non-leisure sitting. Higher BMI was associated with more average daily, weekend, and weekday sitting. High income was additionally associated with less non-leisure sitting. The belief that sedentary behavior is bad for health, physical function, and self-evaluative OE, and lifestyle self-efficacy were associated with multiple sitting domains in both univariate and covariate-adjusted models. CONCLUSIONS: Future work should examine the relationships between motivational, demographic, and disease predictors and objectively measured sedentary behavior over time and across different sedentary behavior domains. Understanding activity changes during and after treatment is needed to identify intervention targets and develop effective interventions.

Duration-Response of Light-Intensity Physical Activity and Glucose Dynamics in Older Adults.

BACKGROUND: Older adults spend 30% of their day in light-intensity physical activity (LPA). This study was designed to determine if increasing the proportion of time spent in LPA would affect glucose control. METHODS: Older adults (N = 9) completed four 3-hour treatment conditions consisting of a seated control and 3 randomized conditions: (1) 20% time spent in continuous LPA, 80% seated; (2) 40% time spent in continuous LPA, 60% seated; and (3) 60% time spent in continuous LPA, 40% seated. Energy expenditure was measured continuously, and glucose was measured prior to mixed-meal ingestion and hourly thereafter. Glucose area under the curve was compared between conditions using Friedman test. RESULTS: There was a significant difference in glucose area under the curve by time spent in LPA (P < .001); specifically, between the seated and 60% LPA (mean difference = 35.0 [24.6] mg/dL, P = .01), seated and 40% LPA (mean difference = 25.2 [11.8] mg/dL, P = .03), seated and 20% LPA (mean difference = 17.8 [22.5] mg/dL, P = .03), 20% LPA and 60% LPA (mean difference = 17.2 [22.5] mg/dL, P = .01), and 40% LPA and 60% LPA (mean difference = 9.8 [7.3] mg/dL, P = .01). CONCLUSION: These results provide experimental evidence to the importance LPA has on metabolic health. If older adults who already spend, on average, about 3 hours per day in LPA, further increase their LPA, they could see benefit to glucose control.

Pattern Analysis of Sedentary Behavior Change after a Walking Intervention.

OBJECTIVES: We examined the pattern of change in sedentary behavior (SB) resulting from a physical activity (PA) intervention in older adults, and the influence of sex on changes in SB. METHODS: One hundred twenty (N = 120) inactive older adults from 2 12-week step/day-target interventions were included in this pooled reanalysis. Participants were randomly assigned to an intervention (STEP) or control group (CON). A Hip-worn accelerometer (Actigraph) was used to assess SB and PA. RESULTS: Significant decreases in SB (-25 minutes) were largely accounted for by the increase in moderate- to vigorous-intensity PA (MVPA; +17.3 minutes). More broadly, data showed that for every 1% increase in proportion of time spent in MVPA, SB decreased by 1.21%. Results of the pattern analysis showed significant pre-post decreases in the number of daily sedentary bouts lasting 10, 20, and 30 minutes and the number of sit-to-stand transitions in the STEP group. Males tended to decrease time spent in longer bouts and females tended to decrease the number of sit-to-stand transitions to achieve lower SB. CONCLUSIONS: Decreases in SB were accomplished through reductions in shorter bouts of SB and likely through a variety of small changes that differed between individual participants and sexes.

Moderating Effects of Weather-Related Factors on a Physical Activity Intervention.

INTRODUCTION: The purpose of this study is to identify whether weather-related factors moderate the effect of a physical activity (PA) intervention. METHODS: Participants (N=204, 77% female, mean age 33 [SD=11] years, mean BMI 28.2 [SD=7.1]) from the Make Better Choices 1 trial, enrolled April 2005 to April 2008, were randomized to one of two treatment conditions: (1) increase moderate to vigorous physical activity (MVPA) treatment group, or (2) decrease sedentary behavior control group. Participants wore an accelerometer for 5 weeks: a 2-week baseline assessment followed by a 3-week intervention. Accelerometer data were used to estimate minutes/day of MVPA. Average daily temperature, day length, and precipitation were obtained from the National Climatic Data Center and combined with the accelerometer data. Linear mixed effects models were used to determine whether these weather-related factors moderated the effect of the intervention on MVPA. Separate models were fit for season, daily average temperature, and day length. RESULTS: There was a significant moderating effect of season on MVPA such that the PA intervention, as compared with control, increased MVPA 10.4 minutes more in the summer than in the winter (95% CI=1.1, 19.6, p=0.029). There was a significant moderating effect of daily temperature such that every 10°F increase in temperature was associated with an additional 1.5 minutes/day increase in the difference in MVPA increase between the two intervention conditions (95% CI=0.1, 2.9, p=0.015). There was a significant moderating effect of day length such that every additional hour of daylight was associated with a 2.23-minute increase in the PA intervention's impact on increasing MVPA (95% CI=0.8, 3.7, p=0.002). CONCLUSIONS: Day length and temperature had a significant moderating effect on change in MVPA during a PA intervention such that the intervention was less effective on colder days and on shorter days, independently. These results suggest that strategies to overcome environmental barriers should be considered when designing PA interventions for adults.