We know that aerobic activity is linked to better physical and mental health. Now, a new review confirms that resistance or weight training can also support mental health. For this meta-analysis researchers reviewed 16 papers with a combined total of 922 participants. They found that resistance training significantly reduced anxiety symptoms in both healthy participants and those with diagnosed anxiety disorders. In fact the effects were larger in those without a diagnosis. And it didn't really matter if participants were much physically stronger at the end, they still got the psychological benefits, which were similar to medication and psychotherapy.
We don't know from this review whether the improvements were from psychological mechanisms (e.g. motivation, sense of achievement) or biological ones (reduced inflammation, increased brain profusion/BDNF). What we do know is that resistance training is a valuable, low cost, relatively low risk, effective intervention for anxiety.
The Effects of Resistance Exercise Training on Anxiety: A Meta-Analysis and Meta-Regression Analysis of Randomized Controlled Trials. Sports Medicine. 2017 doi: 10.1007/s40279-017-0769-0