Move more, feel better: it seems like a simple formula. Physical activity is good for you – no one will argue against it. We humans are built to move our bodies to remain healthy, both physically and mentally. Taking that walk to the supermarket instead of taking the car, or taking the stairs instead of the elevator, are good ways to stay active, feel good and manage stress. The research is promising and compelling: ‘on average’ physical activity can reduce stress, boost your mood, and reduce the risk of depression and anxiety disorders. But what works on average may not work for you, or not today.
Noa van Zwieten is a PhD candidate at the Amsterdam UMC. Her research focus is on the behavioural and affective stress responses in daily life, and how these relate to mental health.
How does the mood-boosting process actually work?
When we talk about physical activity, we don’t necessarily mean hitting the gym or going for a run. Physical activity includes everything you do: from running to your train, to gardening, to climbing the stairs. These small everyday movements have an impact on your physiology: ‘feel-good’ hormones are released. At the same time, moving your body can also help lower levels of stress hormones and activate your parasympathetic system (for more on this topic, read this blog by Artemis Stefani). Together, these effects can make you feel better. The biological mechanisms behind physical activity’s mood-boosting effects are largely similar across humans. Given these shared mechanisms, you might expect that everyone would experience the same mood-boosting effects. Yet, recent research reveals a more complex story: how and when your mood is affected by movement can vary widely from person to person.
The individual reality is complex
Several factors help explain why individuals differ in the mood-boosting effects of physical activity. These factors include how your brain is wired, how your genes influence muscle composition and metabolism, as well as how efficiently the body releases or responds to feel-good hormones. Sociodemographic factors include the effects of age, sex, and socioeconomic status. Psychological and behavioural factors – such as personality, motivation, coping mechanisms, mental and physical health status, and baseline fitness levels – add further complexity to the puzzle of why individuals differ. These factors are crucial to understanding why mood-boosting effects differ between individuals, but they are only one part of the puzzle. Your emotions and activity are constantly shifting throughout the day, depending on timing, context, intensity and your current physiological and emotional state (e.g., stress levels, sleep quality, emotional state). To truly understand how physical activity affects your mood, researchers need to study their dynamic nature in real, everyday life.
Traditional research captures snapshots
This dynamic, fluctuating nature is exactly what traditional research struggles to capture. That is, most studies ask participants to retrospectively report on their physical activity and mood at only one or a few fixed moments (e.g., every month), reporting averages across participants while missing all the moment-to-moment fluctuations within each person. But remember: ‘what works on average may not work for you, or not today’1. Snapshots cannot capture the full movie, especially in the context of physical activity and our emotional responses to it, changing from hour to hour. Add to that, traditional research methods often rely on self-reports to assess physical activity, asking the participant how much and how long they have been physically active and how they felt after that. Although informative and valuable, these self-reports make participants prone to several biases. That is, people may not always accurately remember how active they were over the past week (known as recall bias). Can you remember how much you’ve been vigorously active in the past week? Maybe. But can you remember how you felt during and after these activities, or even during your lighter, everyday movements that are often overlooked (e.g., household chores, walking)? Probably not that accurately. Besides recall bias, people may answer in a way that makes them look more active than they really are (i.e., social desirability bias). While this traditional research has given us much insight into the physical activity-mood link, it misses some crucial information. When and for whom do these mood-boosting effects appear, how long do they last, and how do they change over time? By answering these questions, researchers can design personalised physical activity strategies to support mental health, for example, to reduce depressive symptoms or stress.
From snapshots to movies
Wearable technology, like consumer wearable devices, can help answer these questions. Wearables help facilitate a full, dynamic movie instead of a static snapshot. Instead of one or two self-reported measurements, we can now track physical activity with objective measures continuously during individuals’ daily lives. Mood and stress levels can be repeatedly and frequently assessed with smartphone apps, prompting you multiple times a day: ‘How are you feeling in this moment?’. When combining wearable and smartphone data, we can create a very detailed movie of your daily life. We can see when physical activity affects your mood and stress, how long the effects last, and under what circumstances. At the same time, we can observe how your current mood or stress levels affect whether – and when – you are physically active. For example, some people move more to improve their mood, while others are more active only when they already feel good. These personalized movies create the possibility to capture these moments in time where more physical activity may be most effective in boosting your mood, which differs from person to person. This shift from snapshots to movies forms the foundation for personalised approaches. Think of prompting individuals with low mood or high stress on their wearables to move more at specific moments where they are most likely to emotionally benefit. By looking at this dynamic movie rather than isolated snapshots, we can discover when movement truly makes the biggest difference for each individual, turning physical activity into a simple, powerful, personal tool for feeling better.
Interested in more? Listen to this episode from the Stress Navigation podcast with Eco de Geus to learn more about exercise physiology and measuring it outside the lab.
References
1 For a clear example of how group-level averages can differ from individual patterns, please see: Burg, M. M., Schwartz, J. E., Kronish, I. M., Diaz, K. M., Alcantara, C., Duer-Hefele, J., & Davidson, K. W. (2017). Does Stress Result in You Exercising Less? Or Does Exercising Result in You Being Less Stressed? Or Is It Both? Testing the Bi-directional Stress-Exercise Association at the Group and Person (N of 1) Level. Annals of Behavioral Medicine, 51(6), 799–809. https://doi.org/10.1007/s12160-017-9902-4
