1 Cool season grasses are planted in the summer or early fall. Their vigorous growing season is mid to late fall. These grasses grow best in northern areas with cold winters and mild summers. Cool season grasses include the following:  Kentucky bluegrass, is a fine, dark green grass that grows well in shade.
The erector spinae or spinal erectors is a set of muscles that straighten and rotate the back.
This is called antagonistic muscle action. The working muscle is called the prime mover or agonist. (it s in agony!) The relaxing muscle is the antagonist. The other main pair of muscle that work together are the quadriceps and hamstrings.The prime mover is helped by other muscles called synergists.These contract at the same time as the prime mover. They hold the body in position so that the prime mover can work smoothly.it s in agony!) The relaxing muscle is the antagonist. The other main pair of muscle that work together are the quadriceps and hamstrings. The prime mover is helped by other muscles called synergists. These contract at the same time as the prime mover.