If there is someone who runs for exercise and studies that same amount with all other factors the same as someone who doesn't run for exercise.. who's brain has the bigger brain capacity?
depends what other activity the other person does, activity helps improve brain function the brain is also use it or lose it, just like muscles
Exercise increases neurotrophic growth factor which creates neurogenesis In simple terms, exercise makes you smarter """BDNF acts on certain neurons of the central nervous system and the peripheral nervous system, helping to support the survival of existing neurons, and encourage the growth and differentiation of new neurons and synapses.[9][10] In the brain, it is active in the hippocampus, cortex, and basal forebrain—areas vital to learning, memory, and higher thinking.[11] Certain types of physical exercise have been shown to markedly (threefold) increase BDNF synthesis in the human brain, a phenomenon which is partly responsible for exercise-induced neurogenesis and improvements in cognitive function.[13][20][21][22][23]""""