Yes, he had a lot of muscles
Yes, it improves your strength and helps your muscles. By swimming a lot, you can also lose a lot of weight.
lactic acid accumulation
Muscles are metabolically very active.So they need lot of energy.
yes,a lot!
Mitochondria. :)
Your questions is unclear. Each species has a specific number of muscles.
Probably because swimming uses a lot of muscles and you aren't used to using those muscles.
Yes it does.
it has a lot of calcium wich helps heal bones and muscles
Biceps and Lats primarily, along with a lot of support from the forearm and shoulder muscles.
You should cool you muscles because by moving rigorously a lot of blood is rushed to your muscles in order to help them move. If you don't "cool" your muscles the blood will accumulate in your muscles and 'freeze' or you may get muscle spasms.