% ▁and ▁the ▁right ▁hi pp oc amp us ▁by ▁ 1 . 9 7 % ▁over ▁a ▁one - year ▁period . ▁Sub ject s ▁in ▁the ▁low ▁intensity ▁stretch ing ▁group ▁who ▁had ▁higher ▁fit ness ▁levels ▁at ▁bas eline ▁showed ▁less ▁hi pp oc amp al ▁volume ▁loss , ▁providing ▁evidence ▁for ▁exercise ▁being ▁protect ive ▁against ▁age - related ▁cogn itive ▁decl ine . ▁In ▁general , ▁individuals ▁that ▁exercise ▁more ▁over ▁a ▁given ▁period ▁have ▁greater ▁hi pp oc amp al ▁volumes ▁and ▁better ▁memory ▁function . ▁Aer ob ic ▁exercise ▁has ▁also ▁been ▁shown ▁to ▁indu ce ▁growth ▁in ▁the ▁white ▁matter ▁tract s ▁in ▁the ▁anterior ▁cor pus ▁call os um , ▁which ▁normally ▁shr ink ▁with ▁age . ▁ ▁The ▁various ▁functions ▁of ▁the ▁brain ▁structures ▁that ▁show ▁exercise - indu ced ▁increases ▁in ▁gray ▁matter ▁volume ▁include : ▁ ▁Pref ront al ▁and ▁anterior ▁c ing ulate ▁cort ices   – ▁required ▁for ▁the ▁cogn itive ▁control ▁of ▁behavior , ▁particularly : ▁working ▁memory , ▁att ent ional ▁control , ▁decision - making , ▁cogn itive ▁flex ibility , ▁social ▁cogn ition , ▁and ▁in hib itory ▁control ▁of ▁behavior ; ▁imp licated ▁in ▁attention ▁def ic it ▁hyper activity ▁dis order ▁( AD HD ) ▁and ▁add iction ▁ ▁N uc le us ▁acc umb ens   – ▁responsible ▁for ▁in cent ive ▁s ali ence ▁(" w ant ing " ▁or ▁desire , ▁the ▁form ▁of ▁motiv ation ▁associated ▁with ▁reward )