Hypothesis
This study focused on the positive effect that moderate/high-intensity exercise can have on depression. In research done by Helgadóttir et al. (2018) they found that when compared, those who partook in moderate/high-intensity had a greater decrease in the severity of their symptoms than those who only did low-intensity exercise. Based on the research done by Helgadóttir et al. (2018) I hypothesized that participants in an exercise group who did moderate/high-intensity would have few if any, depression symptoms when compared to those who did no exercise at all. Additionally, I predicted that participants in the exercise group would experience symptom relief, even while dealing with the stress of living in Chicago.
Methods
Participants
To obtain participants, flyers were put up around central Chicago near the University of Chicago providing information about the study. In research done by Helgadóttir et al. (2018), they found significant results using 310 people study. Because of this, 300 participants were chosen to participate in the current study. In order to partake in the study, participants either had to present symptoms of depression or have a history of depression. Participants who came from a family with a history of depression were also allowed to partake. Whether the subjects were being treated for their depression was taken note of, but was not cause for exclusion. Participants ranged in age from 18 to 50 years old. Participants identified as 75% Caucasian, 20% African-American, and 5% Latino. The participant population was made up of 175 females and 125 males. Sixty-five percent of the participants were currently experiencing symptoms of depression, 25% of participants had a history of depression, and 10% came from a family where one or more members had a history of depression. Participants who had medical conditions that prohibited them from exercise were excluded. This information was obtained through a self-report measure. This study and all materials used have been approved by the Institutional Review Board.
Measurements
Beck Depression Inventory (BDI). The Beck Depression Inventory (BDI) is a 21-question, self-report measure that is intended to detect and assess the severity of depression. The first 13 question are meant to assess the psychological symptoms, while the remaining eight questions focus on the physical symptoms. Each question has four possible responses ranging from zero to three, with three being most severe. The researches will take note of the severity and then compare all scores at the end to determine if progress was made. Participants will complete the BDI before, during, and after partaking in the study.
Exercise. For the purpose of this study, exercise will be defined as anything which requires physical exertion and increases the participant's heart rate to between 50% and 70% of their resting heart rate. Partaking in high-intensity exercise will increase the participant's heart rate to between 70 to 85% of their resting heart rate. Target heart rate will vary based on the age of the participant. The older the participant, the lower their target and maximum heart rate will be.
Demographic self-evaluation form. Participants were asked to answers questions about their age, ethnicity, gender, and if they were currently diagnosed with depression or had a history of depression. The form was created by the experimenters and was completed before the participants were able to partake in the study. The questionnaire was consulted again after the study had been completed to determine if demographics had any impact on the results the participants had.
Procedure
Participants were brought into an auditorium on the campus of the University of Chicago. Upon arrival, the participants were told that the study was going to look at the effect moderate/high-intensity has on depression. The participants were then randomly placed into one of two groups. They were either placed in the group that was going to partake in an exercise intervention for the duration of the study or the group that would go on with their lives as usual. There were 125 participants in the exercise group and 125 in the no-exercise group. After being separated into their respective groups all of the participants were asked to complete the BDI.
The exercise intervention consisted of having the participants exercise for around 60 minutes at three times a week for 35 weeks. The participants in the exercise group were also given activity monitoring watches in order to measure the duration and intensity of their workout. Intensity was determined by the maximum heart rate reached during exercise. The participants were allowed to partake in any sort of exercise as long as they reached the moderate/high-intensity requirement.
The initial meeting was held on a Saturday. After receiving all relevant information about the study and completing the BDI, participants were sent on their way. Exercising was to begin the following day (Sunday) as to make sure all participants in the exercise condition started on the same day. Participants were allowed to exercise any day of the week, as long as they do so three times before the following Sunday. Exercising multiple times in one day did count and was not recommended.
Participants in the exercise group also kept an exercise journal where they recorded their workouts. They were told to record the date and time of their workout, as well as their heart rate and corresponding intensity level. Participants were also told to record the type of workout they did, such as weight-lifting or running. They were told they could also record other information such as feelings and mood before and after the workout. Participants were required to weigh themselves and record their weight on the day of their monthly meeting, but were welcome to more frequently if they chose to do so.
Participants from both groups will meet again one month after the initial meeting. Participant in both groups will once again take the BDI. The researchers will take note of the score and compare it to their initial score. Participants in the exercise group will talk with the other members of their group and the researchers for one hour to discuss their progress and what has been working well for them. Those in the no exercise group will also meet for one hour with the other members of their group and researchers. During their meeting time they will watch and read educational materials about the effect exercise has on depression and how living in neighborhoods with poor conditions can lead to depression.
Both groups will continue to meet once a month to fill out the BDI and then split into their respective groups. At the end of the 35 weeks the groups will meet for a final time. They will all fill out the BDI and then all their scores from the previous meetings will be compared to determine the progress, if any, made. The researchers will also collect the exercise journals from those in the exercise group.
Data Analysis
To examine the relationship between exercise and depression, BDI scores from both groups were submitted in a 2 (Group: Exercise, No Exercise) × 3 (Time: pre, 4 months, 8 months) mixed factor ANOVA.