AUTHOR=Li Yu-Mei , Konstabel Kenn , Mõttus René , Lemola Sakari 

TITLE=Temporal associations between objectively measured physical activity and depressive symptoms: An experience sampling study

JOURNAL=Frontiers in Psychiatry

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2022.920580

DOI=10.3389/fpsyt.2022.920580

ISSN=1664-0640

ABSTRACT=Background
This study aimed to examine the relationships between the timing of physical activity and within-individual differences in depressive symptoms, positive affect, and negative affect in individuals with different baseline levels of depressive symptoms.
Methods
Experience Sampling Methodology (ESM) was used to measure real-time depressive symptoms, positive affect, and negative affect in a convenience sample of 78 healthy adults (aged M = 25.46 years, SD = 6.18; 57 females) five times per day for 14 days. We measured physical activity throughout the 14 days by using activity sensors. Baseline levels of depressive symptoms were assessed with the PHQ-9 to build subgroups with low vs. mild-moderate depressive symptoms. 
Results
Physical activity predicted decreased depressive symptom levels, negative affect, and increased positive affect. Associations were stronger for individuals with higher baseline levels of depressive symptoms and for physical activity between 0–30 minutes compared to physical activity between 30–180 minutes before the mood rating. Conversely, levels of depressive symptoms, positive and negative affect did not predict physical activity. 
Limitations
The convenience sample may not have been representative of the general population or people with depression. Accelerometers may not have detected some types of physical activities such as bicycling. Causality could not be inferred because of the observational study design.  
Conclusions
Individuals with higher levels of depressive symptoms may benefit from physical activity. While the effects were strongest for physical activity immediately before the mood ratings, the effects were in the same direction for up to 3 hours before the mood ratings.