The Back Moves the Front

TJ Tomasi

by Dr. TJ Tomasi

College of Golf Senior Faculty and Director of Research

Counterintuitive as it may sound, in the golf swing, specifically the upper body, the back moves the front.

Research conducted in the biomechanics lab at Penn State University studied muscle activity during the golf swing, primarily the left latissimus dorsi of the back (the lat), and the left pectoral major of the chest (the pec) for the right handed player – the reverse is true for the left hander.

During the downswing the target lat helps rotate your lead arm counterclockwise, moving it down and across your chest from the top of your swing.

Then the target pec moves the arm in the opposite direction, toward the midline of your body.

In every golf swing recorded, the target lat began its contraction at the start of the downswing, reaching its maximum activity when the arm was parallel to the ground.

This action pulled the club down toward the ground and closer to the body, allowing the maximum buildup of energy.

As the pulling action of the back muscle began to subside, the target pec became very active, reaching maximum activity just before impact.

This indicates that the role of the pec in the downswing is to put the brakes on the lead arm, thereby slowing it down so its energy can be released via the kinematic sequence to the ball.

The lat and the pec are key muscles that make the kinematic sequence effective, and, since they form an antagonistic pair, they should both be targeted for vigorous exercise.

The message from the research is clear.

For you to have an efficient golf swing, your lead arm must initially speed up as it takes on the energy passed to it from your body coil, then it must decelerate near the halfway point in your downswing in order to pass its energy down the club shaft and into the clubhead at impact.

Thus the recommendation so often heard to ‘accelerate your arms through impact in order to speed up the club’ is troublesome.

As a matter of fact, by speeding up your arms during the second half of your downswing, you retain energy in the arms, preventing it from flowing into the clubhead and down to the ball.

This not only robs you of speed where it counts – at the ball – but because it would mis-position the clubface, it is no doubt responsible for many of the blocked shots and push slices that bedevil those who try to ‘make the club go fast’ with the arms