A slew of studies in recent years has shown that exercise can reduce stress, anxiety and symptoms of depression. Jacob Meyer, associate professor of kinesiology at Iowa State University, wants to know whether different types and doses of exercise benefit individuals, either on their own or integrated into a treatment plan. Unlocking the underlying mechanisms between physical and mental health is key to his overarching goal.

“If we can figure out what’s going on, then we can maximize those mechanisms and come up with the best program or prescription for an individual with anxiety or depression. Without it, we’re rudderless,” says Meyer.

Shedding light on resistance exercise training

One of his new research projects focuses on resistance exercise training. Also known as strength or weight training, resistance exercise sessions typically include multiple sets and repetitions with weight machines, dumbbells or resistance bands. Exercises that rely on body weight, like pushups and lunges, fall into this category, as well.

“Resistance exercise tends to be much more focused in a localized fashion, on the specific muscles being used. Aerobic exercise is more general. Aerobic exercise uses the cardio-respiratory system — your body’s system designed to deliver oxygen to your muscles,” explains Meyer.

Most studies that have tested the effects of exercise on anxiety and depression have used aerobic workouts, like running or cycling. Those with resistance exercise training have been fewer and smaller in size; while the results are promising, Meyer says more robust studies are needed. A recently awarded $3.6 million grant from the National Institute of Mental Health will help make that possible.

Starting this month through the end of 2026, Meyer and his team are recruiting 200 adults with depression for a 16-week exercise trial. Each participant will be randomly assigned to a low-dose or high-dose version of resistance exercise training, performed under supervision in the Wellbeing and Exercise Laboratory, which Meyer directs.

The five-year study aims to answer:

• Does resistance exercise reduce symptoms of depression?
• If so, is the underlying mechanism the flow of blood to the brain and within the brain?
• Is it possible to proactively identify who would benefit most from resistance exercise?

To measure whether resistance exercise reduces depression symptoms, participants will complete regular questionnaires and clinical interviews across the project.

As for the second research question, Meyer points to studies that cerebral blood flow is lower in adults with major depressive disorder.

“There is a lot of research that suggests that people with mental health conditions have areas of the brain that are either under-activated or over-activated, and we think it’s possible there is some re-regulation of brain blood flow patterns through resistance exercise training that may mediate reductions in depression and anxiety,” says Meyer.

The sets and reps from resistance exercise provides what Meyer calls “inconsistent but patterned demands on the vascular system.” It’s a different stimulus than aerobic exercise, which requires a more consistent amount of blood flow, and may lead to uniquely beneficial adaptations.

Using noninvasive techniques, such as Doppler ultrasound, assistant professor of kinesiology Wes Lefferts and his graduate students will measure the study participants’ brain blood flow. They’ll also collect data about the structure and function of blood vessels in the neck that feed the brain.

“This comprehensive approach gives the team the best chance of identifying the effects of major depressive disorder on brain blood flow and the ability of resistance exercise to improve brain blood flow in this group,” says Lefferts.

Exercise as an amplifier of therapy

With a separate $1.5 million initial two-year grant from the National Institute of Mental Health, Meyer is leading a concurrent research project to explore how exercise may amplify the benefits of therapy. The study, which began in November and will run into 2025, consists of an eight-week randomized controlled trial with 40 adults with major depressive disorder. Each week, participants will perform 30 minutes of moderate-intensity exercise or rest quietly while watching a nature documentary and then meet with a cognitive behavior therapist.

Nathaniel Wade, licensed psychologist, professor and associate chair of psychology at Iowa State, oversees the clinical team responsible for the participants’ mental health assessments and therapy.

“One of the most rewarding aspects of this research is that we have the chance to really help people while we are testing new approaches. In past clinical research, the participants have found significant relief and healing all while adding to our scientific understanding,” says Wade.

The study builds off a pilot project Meyer led in 2022. Meyer says exercise may prime or “fertilize” the brain to engage with emotionally challenging work that can happen during therapy. With more robust evidence showing that it works, adding a pre-therapy workout could augment conventional mental health treatments.

“Both projects —the resistance exercise training and the therapy integration — come at the same question but with different intervention approaches. There aren’t many places that are trying multiple, new behavioral interventions for mental health. So, we have a cool opportunity to test several cutting-edge treatment options, all in one place at Iowa State,” says Meyer.