Two molecules that respond to different kinds of movement may help explain the cognitive benefits people get from regular exercise. A recent review of exercise research looked at how cardio and strength training affect the brain across the lifespan, focusing on brain-derived neurotrophic factor (BDNF) and insulin-like growth factor 1 (IGF-1). The review combined findings from human studies, observational research, and animal studies to map how workout frequency, intensity, and duration connect to these molecules.
What BDNF and IGF-1 Do in the Brain
BDNF helps support healthy brain cells and plays a key role in learning and memory. IGF-1 is involved in maintaining and supporting the brain. The review’s core point is that the two molecules are not interchangeable: different types of exercise seem to move them in different ways.
How Cardio Connects to BDNF
Aerobic exercise had the strongest connection with BDNF in the review. Challenging cardio such as running, cycling, and brisk walking was associated with greater increases in the brain-supporting molecule. The research pointed to aerobic exercise at roughly 65% or more of maximum effort, two to three times a week, with sessions lasting at least 40 minutes, as a pattern linked to a stronger BDNF response.
Prior research has also tied aerobic activity to BDNF increases and to neuroplasticity, the brain’s ability to form and reorganize connections. A separate 2026 study reported that a 10-minute aerobic workout using only a full water bottle for light resistance may help boost cognitive function by increasing BDNF. Exercise has a direct effect at the cellular level throughout the brain: it promotes healthy new pathways between neurons and helps rejuvenate existing mechanisms within neurons.
How Strength Training Connects to IGF-1
Strength training showed a different relationship with IGF-1. How often a person trained appeared to matter more than the exact weight lifted or the workout length. The review pointed to resistance training at least three times a week, with consistency appearing to matter more than load or duration for the IGF-1 pathway.
A 2025 study published in GeroScience found that older adults with mild cognitive impairment who did supervised strength training twice weekly preserved brain volume in memory-critical regions such as the hippocampus and precuneus. Some participants exhibited reversed MCI symptoms. Resistance training stimulates myokines, IGF-1, and BDNF production, reducing inflammation and promoting neuron growth.
Why Combining Both May Help
The brain may benefit from a combination of cardio and strength training, not just exercise in general. Making room for both gives a simple way to support brain health while building a stronger, more capable body. The review framed its suggestions as a practical starting point rather than a fixed formula. As one reference noted, any movement is beneficial and will give the brain a boost, and physical activity includes all movement, including walking and doing chores, while exercise is structured activity.
FAQ
What molecules link exercise to brain health?
A recent review of exercise research focused on two molecules: brain-derived neurotrophic factor (BDNF), which supports healthy brain cells and plays a role in learning and memory, and insulin-like growth factor 1 (IGF-1), which is involved in maintaining and supporting the brain.
Does cardio or strength training do more for the brain?
According to the review, aerobic exercise had the strongest connection with BDNF, while strength training showed a different relationship with IGF-1. The two forms of exercise appear to support the brain through different molecular pathways rather than one being better than the other.
How often should you exercise to support BDNF and IGF-1?
The review pointed to aerobic exercise at roughly 65% or more of maximum effort, two to three times a week, with sessions lasting at least 40 minutes, as a pattern associated with a stronger BDNF response. For IGF-1, the review suggested resistance training at least three times a week, with consistency appearing to matter more than exact weight or session length.
