Walking alone is insufficient to maintain type II muscle fibers, which transition to type I fibers with age.

“Walking is wonderful but is walking enough to maintain those type two fibers it's not you will see a transition and we've all seen our aging parents I mean my dad is in his 70s he's very fit but he used to be a Collegiate wrestler he went to warten he was Captain of his wrestling team Dad you're a lot smaller and part of the reason is the fail the failure to focus on hypertrophy and those are those type two fibers those type two fibers that transition with age to more type one fibers those long lean fibers you go from bigger to Bulky to less choosing activities to maintain those fibers”