Here’s yet another reason strength training may be worth prioritizing: It could be linked to better mental health. That’s the major takeaway from new research on the impact of different types of physical fitness on the risk of depression.
The study, which was published in the Journal of Affective Disorders, didn’t find the same association for cardiorespiratory fitness, raising all kinds of questions. Of course, the research isn’t suggesting that you ditch your current treatment for depression or cardio to focus exclusively on strength training. Instead, it can be an adjunct to what you’re already doing.
So, why might building muscle help combat symptoms of depression? Experts break it down.
Meet the experts: Amy Taylor, PhD, study co-author and senior research fellow in the Department of Surgery and Targeted Intervention at University College London; Michael Brustein, PsyD, a clinical psychologist in New York City; and Thea Gallagher, PsyD, clinical associate professor of psychology at NYU Langone Health.
What did the study find?
For the study, researchers analyzed data from more than 341,000 adults between the ages of 37 and 73 who participated in the UK Biobank, a long-term biomedical database.
The researchers then used a technique called Mendelian randomization to use natural genetic differences between people to test for association. “Because these genetic differences are randomly assigned at birth, the method helps overcome common issues in observational studies, such as confounding (where other factors such as education or diet may explain an apparent link) and reverse causality (where it is unclear what the direction of the relationship is)” explains Amy Taylor, PhD, study co-author and senior research fellow in the Department of Surgery and Targeted Intervention at University College London. “Here, we applied this approach to ask whether a genetic tendency towards greater muscle strength and better fitness is linked to mental health outcomes.”
The researchers specifically looked at genetic variants linked to cardiorespiratory fitness and genetic variants tied to grip strength, which was used as a proxy for overall muscle strength. The team also looked at depression based on the participants’ self-reported history and hospital records, along with specific symptoms of depression (measured from a questionnaire), to get a better sense of the participants’ mental health.
After analyzing the data, researchers found a significant association between having a higher grip strength and lower risk of depression. Specifically, for every 0.1 kilogram increase in grip strength per kilogram of body weight, participants were estimated to have a 14 percent lower risk of depression. They did not find a link between having genetic markers for cardiorespiratory fitness and a lower risk of depression or depressive symptoms.
A higher grip strength was also linked with a lower risk of certain depression symptoms, such as reduced ability to experience pleasure and changes in appetite. People with higher grip strength also had a lower risk of depressed mood, extreme fatigue, and trouble concentrating, which are all linked to depression.
There was a stronger link for women than men
Interestingly, Taylor says her team found “clear differences” between women and men in how much muscle strength is linked to certain symptoms of depression.
In women, an increase in grip strength of 0.1 kilograms per kilogram of body weight was linked to a 33 percent lower risk of an inability to find pleasure in activities, a 30 percent lower risk of depressed mood, and a 26 percent lower risk of issues with concentration. “In men, we did not see clear evidence that the same increase in grip strength was linked to these symptoms,” Taylor says.
Why might building muscle help with depression?
Taylor says she was “somewhat surprised” to find little evidence that cardio could impact symptoms of depression in this specific study, given that previous studies linked having better cardiorespiratory fitness with a lower risk of depression.
She says it might reflect other things at play, like people getting more social support when they do cardio, which can protect against depression. Taylor also mentions that reverse causation may play a role, where being depressed makes you less likely to engage in physical activity and cardio.
But it could also be that having muscle strength helps serve as a “biological buffer” against feeling lethargic or not finding pleasure in activities you used to love, says Michael Brustein, PsyD, a clinical psychologist in New York City.
“Cardio is often a game of endurance—the ability to withstand or ‘get through’ the day,” he says. “Strength is about agency—the ability to exert force. For someone struggling with the psychic paralysis of depression, the tactile, immediate feedback of moving a heavy object provides a sense of self-efficacy that a long, slow walk cannot replicate.” Being strong can also help people feel less like they’re coping and more like they’re capable, he says.
What should the takeaway be?
Hold up before you toss your cardio workout plans out the window. “This challenges the long-standing idea that cardiorespiratory fitness is a driver of depression risk,” she says. “It doesn’t contradict the idea that cardio—or all exercise—is good for mental health.”
Cardio still offers plenty of mental health perks, including reducing rumination. And, if you do cardio with other people, like a group fitness class or run club, you can also see mental health perks, Thea Gallagher, PsyD, clinical associate professor of psychology at NYU Langone Health, adds.
Ultimately, the findings make the case for strength training, but not at the expense of cardio. “We shouldn’t abandon cardio, but resistance training should be viewed as non-negotiable mental health hygiene,” Brustein says. “You don’t need to be a bodybuilder—aim for two to three sessions of resistance training per week to maintain the neurological ‘activation’ of strength.”
Gallagher agrees. “Don’t completely get rid of cardio,” she says. “There can be plenty of health benefits. But incorporate lifting into your routine.”
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