Does physical activity reduce our symptoms for depression, anxiety and other mental health challenges? Does our current research give any clear guidelines on what helps, how often, and how much physical activity shows benefits for improving our experience of these diseases? This week’s conversation between Danny Lennon and Dr. Brendon Stubbs explores the strengths and limitations of the evidence.
Early in the conversation, Dr. Stubbs mentions that one of his passions is meta research–exploring how good the body of research on a particular topic is and evaluating where it needs improvement–and this is a theme throughout the conversation. While a listener will glean some hope about the potential for benefits from physical activity on mental health symptoms, there’s a lot more here teaching us how to have healthy skepticism for the research and popular conversations that arise from reporting on it.
One of my favorite points he makes around interpretation of research is a detailed discussion on the problems with publication bias towards positive results. If someone tests an intervention and it shows an impact, it is far more likely to be published than if it shows no impact. This skews the data available to make it potentially disproportionate to the actual likelihood of success for a particular intervention. Dr. Stubbs uses a wonderful analogy for this, referring to it as the “shop window” of research, with the best and most attractive data on display. There are statistical tools one can use to help researchers identify to what degree the data are skewed towards a particular result, but for the rest of us, knowing there’s publication bias towards positive results needs to be one of the facts we hold onto to help us maintain a certain amount of healthy skepticism towards particularly positive outcomes.
This means the research we have available on physical activity and depression and other mental health symptoms is likely skewed as well. It is difficult to assess the absolute level of improvement a person might experience from regular physical activity. However, there is other information, including from a few well controlled trials, some wide-ranging mechanistic data, and many observational studies that lead Dr. Stubbs to conclude that there are measurable improvements from regular physical activity on mental health for many people.
Interestingly, and new to me, he points out that while any activity seems to have some protective effect, there seems to be increased benefit for folks who have both increased strength and improved cardiorespiratory health. And while he is very cautious to not make specific recommendations on the matter, my sense is that if folks want to protect themselves the most, they would be best served by building routines that include both kinds of activity regularly into their schedule.
Which puts a whole new spin on the conversation around the interference effect. Lots of lifters, and I suspect more women than men, prefer to do a combination of lifting and some kind of cardio endurance activity like running or biking. Whenever that’s being discussed, physical fitness and avoiding one preventing improvements in the other, tends to be the entirety of the discussion. Now I’m wondering if we need to broaden the conversation and make sure we’re also ensuring our mental health is being adequately served by our programming as well?
There’s a lot more interesting stuff in this conversation, and I feel like I could write a book with all the questions and ideas that popped into my head while listening to it! Especially at the end, when Dr. Stubbs really began to sing my tune when he went into how research is inaccessible to the people who most need the information! I don’t think I’ve written about it on the blog before now, but I was once on the track to becoming a traditional academic–working as a biologist and doing research. But I kept receiving the critique that I didn’t communicate like a researcher. I avoided using specialized language and therefore wasn’t viewed as sciencey or “professional” enough. And it was intentional–I wanted my research to be accessible to anyone with an interest in my field. I wanted it to make the world a better place, which meant getting beyond the narrow bubbles of academia and into the public sphere. So I switched gears and went into public education. We need research to be accessible, to be reported in more honest and less sensational ways, and for there to be more dialogue between researchers and policy makers, and I love that Dr. Stubbs calls it out. Danny suggests it’s a conversation for another time, and I hope he invites Dr. Stubbs back for it!
Progressive Strength 
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