These physical activities have been used in the exercise literature as measures of physical fitness and are both safe and simple to learn in an in-lab setting . For all activities, duration of time spent in each activity and number of attempts were assessed. For study 2, participants were asked to complete a shortened Trier Social Stress Test , during which participants delivered a 3-minute speech presenting their qualifications for a dream job to a panel of two evaluators while physiological stress responses were assessed .Across both studies, we used the same measures obtained at the same intervals to assess subjective well being. We replaced missing values with the mean of available items if ≤half of the items were missing, otherwise we treated the scale as missing . State optimism, considered a manipulation check for the optimism intervention, was measured at baseline, mid-study, and post-intervention with seven items from the validated State Optimism Measure . Participants were asked how they felt ‘right now’ on a scale of 0 to 10 regarding expectations for their present and the future. A total score was created by averaging scores across all seven items. In Study 1, α’s ranged from 0.91–0.92 and, in Study 2, from 0.89–0.90. Confidence about the future was assessed by asking participants to rate, on a ten-point scale ranging from 0 to 10 ,black flower buckets how they believe the challenges in their lives right now will turn out. It was measured at baseline and post intervention using the validated Life Orientation Test Revised .
Responses were modified to a seven-point continuum, ranging from ‘strongly disagree’ to ‘strongly agree,’ based on prior work suggesting the 7-point scale is more suited for electronically distributed questionnaires . The total optimism score is the sum of the three positively worded items and the three negatively worded items reverse-scored, with higher scores reflecting higher optimism. In Study 1, α’s ranged from 0.79–0.80 and, in Study 2, from 0.74–0.85. Anxiety, depression, and aggression were assessed at baseline, mid-study, and post-intervention with items from the State-Trait Personality Inventory . Using a seven-point scale, respondents rated the degree to which they agreed with each statement. The final anxiety, depression, and aggression scores were calculated by averaging across items, with higher scores reflecting higher levels of each construct.Positive affect and negative affect were assessed at baseline, mid-study, and post-intervention by the Positive and Negative Schedule , which included ten items capturing positive affect and ten items capturing negative affect . Response options ranged from 1 to 7 . After completing the in-lab writing tasks and interview, participants were asked to complete a stepping task and a sit-to-stand task. For the stepping task, participants were asked to step up and down on a 14-inch high step platform at a rate of 22 steps per minute , until they were too fatigued to continue . Participants were asked to make as many attempts as they wanted for up to a total of 15 minutes. The research assistant recorded the duration of time participants spent stepping across all attempts, as well as the total number of attempts made. The final stepping task score was calculated by the duration divided by the number of attempts.Participants were asked to perform a sit-to-stand exercise.
This involved sitting in the middle of the chair and crossing their arms with each hand on the opposite shoulder and then completing sit-to-stand cycles at a rate of 22 cycles per minute. Participants were first asked to attempt this task for up to 60 seconds. If they decided to continue, the duration requested for each subsequent attempt increased by 30 seconds whereby the second attempt lasted up to 90 seconds and the third attempt lasted up to 120 seconds. As with the stepping task, the research assistant recorded the number of attempts and total duration completed. The sit-stand task score was created by dividing total duration by number of attempts.Physiological measures included measures derived from electrocardiography and impedance cardiography using ECG and NICO modules integrated into an MP150 Data Acquisition System with signals sampled at 1000 Hz. Spot sensors placed in a modified Lead II configuration measured ECG, and four mylar bands that completely encircled the neck and torso measured ICG. From these measures, we derived high-frequency heart rate variability and pre-ejection period . PEP is a time based measure of the contractile force measured from the time the ventricle contracts to the opening of the aortic valve. Shorter time indicates greater increases in sympathetic nervous system activity. RSA provides a relatively pure measure of parasympathetic nervous system responses, whereas PEP provides a relatively pure measure of sympathetic nervous system responses. We also collected blood pressure responses using a Colin Prodigy blood pressure monitor at 7 targeted times during the 2-hour visit. Our BP timing included end of the resting baseline, post-writing, post-interview of writing, beginning of speech preparation, beginning of speech delivery, beginning of math task, and end of math task.For both studies, we trained coders to evaluate the in-lab writing tasks to assess the optimism and affect conveyed in the essays. Coders were trained by first coding approximately 10% of the essays, and the Inter-rater reliability was assessed and found to be satisfactory.
Coders then met with other coders to clarify conceptual categories and calibrate their evaluations. Subsequently, each essay was then coded by at least two different judges. We averaged coders ratings at the item level and took the mean of the items to obtain final scores for optimism, positive affect, negative affect, and explanatory style. Optimism was judged by evaluating goal-oriented thinking and perceived resources . Judges provided ratings ranged from 1 to 7 . Study 1: alpha for the intervention group: α = 0.86 and control group: α = 0.82; Study 2: intervention group: α = 0.90 and control group: α = 0.74. Affect was evaluated by judges by completing a PANAS 20-item scale, which we modified to include feelings of optimism, gratitude, resentment, and pessimism in addition to the standard items. All items were rated on a 5-point scale ranging from 1 to 5 . Items that describe positive feelings were averaged to obtain a score for positive affect, and items that described negative feelings were averaged to obtain a score for negative affect. , α = 0.85 ; negative affect α = 0.71 , α = 0.77 ; Study 2: positive affect α = 0.95 , α = 0.93 ; negative affect α = 0.81 , α = 0.70.For both studies, we first evaluated the effectiveness of the randomization procedure by comparing the distribution of the demographic characteristics across the intervention and control groups, using chi-square tests or t-tests as appropriate. We then examined the pooled data from the two studies and conducted multilevel mixed-effect models to evaluate the combined effect of the manipulation on changes in optimism and the common self-report measures. We treated time as a fixed effect and study sites as a random effect. Next, we examined the effect of the intervention on self-reported outcomes and study specific outcomes. In Study 1, we conducted an ANOVA with condition as the between-subjects factor and self reported outcomes and in-lab exercise outcomes as separate dependent variables. For in-lab exercise outcomes,french flower bucket we conducted sensitivity analyses to additionally adjust for baseline self-report physical activity which was assessed by asking participants the number of days they had engaged in moderate physical activities, such as bicycling at a regular pace or doubles tennis. In Study 2, we used an ANOVA to evaluate reactivity values across the four physiologic responses: RSA, PEP, and systolic and diastolic blood pressure . Reactivity was derived by subtracting the last minute of baseline from each minute of the stress task for each physiological response. In order to understand whether the intervention effects were due primarily to increases in positive affect rather than optimism per se, we conducted sensitivity analyses on all physical activity and stress reactivity outcomes to also control for increases in positive affect. For essay coding, we conducted moderated regression analyses to predict psychological, physical activity, and physiological outcomes with condition, essay-coded optimism, and their interaction. The goal of these analyses was to determine if there was an association among more optimistic terms in the essay and better health-related responses in the lab. All analyses were performed using SAS 9.4 and figures were created using R. This study examined effects of induced optimism on in lab physical activity and stress reactivity through two experimental studies with community-dwelling individuals. Across both studies, the intervention led to greater increases in short-term optimism and positive affect in the intervention group compared with the control group. In general, coder-rated optimism and positive affect were associated with better performance on the in-lab physical activity tasks and healthier forms of stress reactivity.
However, we found little to no evidence that the intervention led to reliable changes in self-reported anxiety, depression, and aggression nor did we observe differences in in-lab physical activity and stress reactivity. Our findings that the writing tasks led to greater improvement in self-reports of optimism and positive affect in the intervention versus the control group are consistent with previous studies conducted in other populations. For example, in a study of 82 students, individuals who did versus did not receive a positive psychological intervention consisting of writing tasks exhibited greater improvement in optimism and positive affect . In another study of 54 Dutch-speaking participants, most of whom were students, a best possible selves writing intervention led to larger increases in optimism compared with writing about a daily activity task . Our research extends these findings to two larger samples of diverse, community-dwelling populations and provides further evidence that this type of intervention can be effective in boosting short-term optimism and positive affect.These findings notwithstanding, we did not find evidence that experimentally induced optimism influenced in-lab physical activity. In contrast, observational studies have repeatedly demonstrated that higher self-reported optimism levels are associated with greater engagement in physical activity or buffer against the harmful effects of stress on health . However, it is notable that our intervention was able to change participants’ exercise beliefs and improve perceived benefits of exercise. Perhaps the small increases in optimism that we obtained from the intervention were insufficient to change subsequent health-related behavior. This may be especially true for health behaviors like physical activity, which are largely habitual. Once established, health behavior is deeply embedded in individuals’ daily routines, and thus changes in behavior may require longer interventions with more substantial changes in optimism. We observed some differences in stress reactivity by condition with induced optimism associated with less vagal withdrawal and lower sympathetic nervous system activation – that is, both less PNS withdrawal and less SNS activation during the stress task. Together these findings suggest participants in the experimental condition had less arousal than participants in the control condition. We might speculate that the optimism condition increased a sense of calm resulting in less arousal during the stress task. However, it is important to note that the intervention did not result in differences in resting physiology nor in blood pressure reactivity, which are more closely associated with better physical health. Despite the null effects of our optimism intervention on in-lab physical activity, we found effects of coder-rated optimism and affect from essays on outcomes in both studies. Overall, greater coded optimism was associated with greater persistence in both physical activity tasks and less vagal withdrawal during the stress tasks. These findings raise several interesting possibilities for understanding our findings and the relationship of optimism with our outcomes of interest. One possibility is that optimism as reflected in writing rather than based on direct self-report more accurately captures participants’ true levels of their positive expectations. A second possibility is that optimism as reflected in writing provides a type of dose-level response such that individuals with more optimistic orientation in their writing benefitted most from the intervention. Our study has several limitations. Although we excluded individuals who were highly physically active from Study 1, we did not establish a pre-intervention exercise assessment. Doing so might have increased our precision in determining if the intervention increased exercise in the lab.