Amazing images. I think it very true that we allow ourselves to rust out from lack of use rather than wear out. This is equally true of the brain..keep challenging it (and keep blood flow to it ) through thought and exercise.
Would the result be similar if the 74 year old only swam? I expect that some weight bearing exercise would also be needed; especially to maintain bone density.
This is great news for me...I turned 60 a couple of months ago...and also decided to train for my first tri. Total Immersion has helped me tremendously in my swim. My Doctor thinks I'm crazy...but I'm having fun!