your brain and heart muscles, plus your tounge and face muscles. (your heart is technechly an organ)
p.s. I know I spelled a lot of words wrong in this answer (see slashed through words) so don't spell them the way I did
in karate muscles mostly used are leg and arm muscles
Most muscles used by the goalkeeper is their eyes and hands.
Mainly your arm, but all muscles are used.
Your Heart!
Most of the muscles of the body are exercised when running. Of course the foot and leg muscles are needed the most but the muscles of the torso and upper body are used as well.
It is unknown the exact number of muscles used to whistle. However, there are two muscles that are used the most, and they are the orbicularis oris and buccinator muscles.
the diaphragm is the muscle(s) that are most important muscle used in inspiration (inhalation)?
The myocardium, or heart, is the most used muscle in the body.
frownin
the tongue and jaw
For many people it's the talking muscles. For runners it's the leg muscles. For barmaids it's the biceps/triceps.
Biking gives a good work out of all the muscle groups