Lifting weights might also lift moods, according to an important new review of dozens of studies about strength training and depression. It finds that resistance exercise often substantially reduces people’s gloom, no matter how melancholy they feel at first, or how often — or seldom — they actually get to the gym and lift.
There already is considerable evidence that exercise, in general, can help to both stave off and treat depression. A large-scale 2016 review that involved more than a million people, for instance, concluded that being physically fit substantially reduces the risk that someone will develop clinical depression. Other studies and reviews have found that exercise also can reduce symptoms of depression in people who have been given diagnoses of the condition.
But most of these past studies and reviews have focused on aerobic exercise, such as walking or jogging. Far less has been known about the possible benefits, if any, of strength training for mental health. One 2017 analysis of past research had found that strength training can help people feel less anxious and nervous.
But anxiety is not depression. So for the new study, which was published in May in JAMA Psychiatry, the same researchers who earlier had examined anxiety and resistance exercise now turned their attention to depression.
They wanted to see whether the available research could tell us if lifting weights meaningfully affects the onset and severity of depression. They also sought to determine if the amount of the exercise and the age, health or gender of the exercisers would matter. The researchers began by gathering all of the best past studies related to resistance exercise and depression. They were interested only in randomised experiments with a control group, meaning that some people had been assigned to start exercising while others had not. The experiments are the gold standard for testing the effects of exercise and other interventions.
They also had to include testing for depression before and after the training. The researchers ultimately found 33 experiments of weight training and depression that met their criteria. The studies involved 2,000 men and women, some of whom had been diagnosed with depression, while others had not. The researchers aggregated the results from all of these studies and then began digging through the data.
They found that resistance training consistently reduced the symptoms of depression, whether someone was formally depressed at the start of the study or not. In other words, if people began the study with depression, they felt better after taking up weight training.