It pumps the blood in and out of the heart. If I remember right I think that’s it.
        
             
        
        
        
Pretty sure its scavenger, the others make no sense 
 
        
             
        
        
        
They speed up your heart rate and get your body loosened up for further exercises
        
             
        
        
        
It would help bc building a dam would stop the water from crashing everywhere