Weight training has the biggest effect on __________. a. cardiac muscles b. smooth muscles c. involuntary muscles d. skeletal muscles

d. skeletal muscles Weight training has the biggest effect on the skeletal muscles. When a person is engaged in weight training activities the skeletal muscles are forced to move beyond their comfort zone because of the added weight. As a result, muscle fibers develop micro-tears. These micro-tears when they regenerate through time increases the number of muscle fibers and the size of the fibers themselves.