It has long been a cliche that muscle bulk doesn't equate with intelligence. Most of the science about activity and brain health has focused on the role of endurance exercise in improving brain functioning.
Aerobic exercise causes a steep spike in blood movement to the brain, an action some researchers speculated might be necessary to create new brain cells, or neurogenesis.
Running and other forms of aerobic exercise have been shown, in mice and men, to lead to neurogenesis in the parts of the brain associated with memory and thinking, providing another compelling reason to run.
Few researchers thought muscle bulk would have a similar effect. But recent studies intimate otherwise. It's not easy to induce a lab rat to lift weights, so researchers developed clever approximations of resistance training to see what impact adding muscle and strength has on an animal's brain.