Written by Erin Yeh
Physical activity is commonly associated with improved symptoms of depression and anxiety. However, it’s not just the frequency of exercise that matters, but also the level of intensity.
“From a mental health perspective, intensity of physical activity is key, not just increased movement per se,” says Maisa Niemela, an assistant professor at the University of Oulu in Finland. press release. Niemelä and her team investigated movement behaviors — sedentary behavior (SB), light physical activity (LPA), and moderate-to-vigorous activity (MVPA), which is defined as intense enough to leave you a little breathless — and assessed how each affected participants’ symptoms of depression and anxiety over a 24-hour period. The results were published in Depression and anxiety (DOI: https://doi.org/10.1155/da/6881070).
Assess symptoms of depression and anxiety
The research team collected data from the Northern Finland 1966 Birth Cohort, a cohort study consisting of people born in 1966 who received follow-up over the decades. The current study collected data from the most recent follow-up in 2012, making the participants 46 years old at that time. Over the course of 14 days, movement behaviors were recorded using an accelerometer worn on the hip and participants’ self-reported sleep duration. Movement behaviors were stratified by synthetic linear regression and further examined by time reallocation analysis to determine the relationship between movement behaviors and symptoms of depression and anxiety over 24 hours.
Three assessment tools were used to measure symptoms of depression and anxiety: the Beck Depression Inventory-II (BDI-II), the Generalized Anxiety Disorder Assessment (GAD-7), and the Hopkins Symptom Checklist-25 (HSCL-25). The BDI-II is a 21-item self-reported questionnaire that focuses on the main symptoms of depression and is used to determine the severity of depression. The GAD-7 is a highly sensitive and specific primary screening tool for identifying symptoms of anxiety. The self-administered questionnaire contains 7 items covering the main symptoms of anxiety disorders. Finally, the HSCL-25 is a questionnaire consisting of 25 items (10 relating to anxiety, 15 relating to depression).
The accelerometer was worn during waking hours, and participants had to provide four or more valid days of accelerometer measurement, which was defined as less than or equal to 10 hours of wear time. In total, 4490 participants had valid accelerometer data. The average accelerometer wear time was 12.8 days, with 450 minutes per day spent sleeping, 435 minutes per day in SB, 342 minutes per day in LPA, and 45 minutes per day in MVPA. About 57.2% of the participants with valid data were female, and it was found that more male participants participated in SB and MVPA than female participants. Notably, MVPA had the largest difference in relative log ratio between male and female participants.
Work harder, not more
More time spent in MVPA and sleep was consistently associated with lower levels of depression and anxiety symptoms while more time spent in SB and LPA was associated with higher levels of depression and anxiety symptoms. Specifically, the BDI-II and GAD-7 questionnaires reported that 90.7% and 79.3% of participants, respectively, had minimal symptoms of depression and anxiety. For the HSCL-25, 89.9% of participants were found to have no symptoms of depression and anxiety.
When conducting a synthetic regression analysis, the team found that more time in MVPA and sleep was positively associated with depressive and anxiety symptoms while more time in LPA and SB was negatively associated across all three assessment models. Notably, when 30 minutes of SB was replaced by MVPA, the BDI-II score was 9% lower. 30 minutes of sleep or replacing LPA with MVPA showed a 5% lower score on the same assessment tool. When 30 minutes of MVPA was replaced with sleep, SB, or LPA, depression scores increased by 15-20%.
It is not yet fully understood why MVPA appears to reduce symptoms of depression and anxiety, but the study provides further evidence that MVPA is the movement behavior most beneficial for symptoms of depression and anxiety. More research is encouraged to fully determine the effects of MVPA on depression and anxiety.
The team stressed the importance of adequate sleep. They reported that increasing SB or LPA at the expense of sleep showed adverse outcomes, and replacing SB or LPA with sleep showed a significant reduction in symptoms of depression and anxiety. While physical activity plays a crucial role in mental health, it does not replace the benefits of sleep.
Great potential, despite limitations
Although the sample size was large, the results may not be representative of the entire original population. The cohort analyzed was from only one point in time. For this reason, it cannot be fully determined whether movement behaviors caused changes in symptoms of depression or anxiety. Furthermore, the increasing use of digital technology and social media in recent years may impact how people spend their time and how sedentary behaviors relate to mental health. In addition, participants who met study requirements had lower levels of depressive and anxiety symptoms than those who did not fully participate, which may have affected the final results.
Sleep duration was self-reported, leaving room for error on the part of participants, as it is common for people to over- or underestimate the amount of sleep they get. Naps are also not included, so total sleep time may not be fully calculated. The use of questionnaires opens the possibility of recall bias, and the three different assessment tools differ in what they measure. The study also did not take into account external influences, such as seasonal changes that lead to seasonal depression.
The group was quite homogeneous, containing only individuals of the same race and age. The study also did not examine whether participants’ movement behaviors differed on weekdays compared to weekends. Many people may be sedentary during the work week but may also be “weekend warriors.”
However, the study findings correlate with previous studies that have shown evidence that MVPA has greater benefits for symptoms of depression and anxiety. MVPA combined with adequate sleep leads to the best results. Although any movement is better than inactivity, increasing physical activity should not come at the expense of sleep. Instead, the researchers encourage that the 24-hour day should be viewed as a balanced unit Press release.
