What is the most important muscle for each swimming stroke?

Question

such as breast , front crawl , butterfly , backstroke

Answer 1

Freestyle - Arms and Legs

Backstroke - Shoulders, Arms, and Legs

Butterfly - Shoulders, Arms, Legs, and Hips/Abdomen

Breaststroke - Shoulders, Forearms, and Legs

Answer 2

for breastroke, your legs because they help propel you forward, for "front crawl" or freestype your arms, butterfly, you arms, and backstroke your arms and legs. And also your core is important in every stroke.

Answer 3

Most likely the latissumus dorsi (the lats).  Most people think that stroke strength comes from the front of the body (the pectoralis major) but, in reality, it is the lats for all strokes.

When I coach my swimmers (about 30 years worth of coaching), I instruct them to roll their body, anchor their hand in the water and feel the lats lock and pull on the arm ... I call it an arm full of water (elbow slightly bent, finger tips facing the bottom of the pool).