Generally healthy , active participants ( n = @ ; age = @ @ years ) were assigned randomly to control ( n = @ ) or one of five @-week exercise programs : ( @ ) @-min brisk walking @/week ( n = @ ) , ( @ ) @-min brisk walking @/week ( n = @ ) , ( @ ) @-min brisk walking @/week ( n = @ ) , ( @ ) @-min brisk walking @/week ( n = @ ) , and ( @ ) @-min running @/week ( n = @ ) , in addition to their regular physical activity .