The spine includes thirty-three vertebrae. A vertabra is a bone structures that include a cylindrical front part, with two bones sticking out on either side at the back. The bones at the back intertwine to create a canal to house and protect the spinal cord. Nerves leave the spinal cord through small openings between the bones at the back of the vertebra.
Of the thirty-three vertebrae, nine at the bottom are fused and do not move; however, twenty-four at the top are separated by disks, which are like cushions. These cushions allow each vertebra to move slightly relative to the vertabra above and below.
Cumulatively, these small movements between individual vertebrae allow the spine to bend forward, bend backward, tilt to the left, tilt to the right, and twist clockwise and counter-clockwise.
Muscles contractions cause the movements in the spine. Muscles at the front of the body in the abdomen and chest contract to pull the top of the spine forward, causing the forward bend in the spine. Muscles at the back of the spine contract to cause the top of the spine to end backward, although the spine does not bend readily in this direction. Muscles at the side of the body contract to pull the top of the spine to the left or right. These movements are relatively straight forward. The spinal twist is less so.
To get an intuitive feel of the spinal twist, sit on a bench or chair in front of a mirror, rest a club across your upper back below your shoulders (to ensure you are not moving your shoulder sockets), hold it in place with your two hands, and gently rotate your shoulders clockwise and counter-clockwise. Keep the club parallel to the ground to ensure that you are rotating your shoulders. Sitting in a chair ensures that your hips are stationary so that all rotation occurs in the spine between the hips and the shoulders. The club that you see in the mirror should be on the horizontal plane throughout.
Several muscles groups are involved:
Note that the spinal twist is a relatively simple motion controlled by large muscles in the abdomen and back with relatively few opportunities for mistake. Unlike movements that use ball and socket joints, it is relatively easy to get the spinal twist right.
How much can you twist your spine? The first consideration should be your health; you certainly do not want to injure your back by overdoing the spinal twist. However, there is much you can do to increase your ability to both twist your spine and protect spinal health.
In a normal, healthy person who has warmed up the spinal muscles, a spinal twist of 120 degrees (60 degrees in clockwise and counter-clockwise directions) should be attainable without assistance. If you use hands and arms to assist in the twist, you should be able to rotate up 160 degrees in total, or 80 degrees in clockwise and counter-clockwise directions. For most people, the primary constraint on spinal twists is muscle weakness, not inflexibility in the spine.
Spinal health is important. Muscles pulls occur frequently. There are a number of muscles tied to the spine; they function among other things to protect the spine. Muscles pulls can be reduced through proper warm up, stretching exercises, and good swing techniques.
Disk damage is a major concern. The disks separating the vertebrae can withstand a lot of pressure. The spinal twist should put equal pressure on all parts of the disk. Bending forward, or backward, or to either side, would focus pressure on one side to which the bending takes place. Intuitively, twisting would appear to be healthier than bending. Also intuitively, the combination of twisting and bending could be problematic, since a bend would put additional pressure on the side of a disk that would already be slightly stressed from the twisting.
The "spinal twist" is different from a "spinal tilt". The "spinal tilt" occurs through the contraction of muscles on your sides. The spinal tilt will be the subject of Chapter 9. The focus here is the spinal twist.
Expert studies of the golf swing have noted that players who hit the ball the farthest frequently do so because of greater "spinal twist". One way to look at the golf swing is a twist to coil the spine on the back swing, followed by a fast twist in the opposite direction to uncoil the spine on the downswing.
To get a sense of the impact the spinal twist can have within the golf swing, remain seated in front of the mirror, grip the club as you would in a golf swing, hold it out in front of you, ensure that your shoulders and arms remain stationary, twist the spine, and observe the range of movement in the club head from the spinal twist.
We noted above that the unassisted spine can twist about 120 degrees. Of this, 60 degrees occurs in the back swing and the downswing to the start position. In the modern swing, the spine has typically rotated perhaps 10 degrees beyond the start position at the point of impact. Thus, the total rotation in the downswing would be about 70 degrees. This rotation at the centre of your swing creates considerable movement of the club head.
Because the spinal twist occurs with the spine bent forward at the hips, the shoulders do not remain parallel to the ground within the swing. In the backswing, the trailing shoulder will be higher than the lead shoulder because the spine is bent forward. When you look at someone else's swing, or observe videos of your own swing, you need to look closely to see the spinal twist.
Because the shoulders appear to change elevation during the swing, a common swing problem is that golfers tilt the spine to get the change in shoulder elevation during the swing, rather than twisting it. As we shall see in Chapter 9, the spinal tilt has a role to play in the golf swing, but if done at all, it should be done with, not instead of, the spinal twist.
You can work on your spinal twist away from the golf course. Simply sit in a chair, put a club across the back of your shoulders, rotate clockwise and counter-clockwise, and concentrate on the contraction of the three major muscles involved. Then, insert this muscle awareness into your golf swing.
Take your back swing and hold your position at the top of the swing. You should feel the contraction of the three muscle groups. If you don't feel the contraction of all three muscles, you may not be turning to your maximum potential. Now take a slow downswing and follow through. Again, feel the muscle groups being used.
As a final note, the spinal twist is a potential source of power in the golf swing. The long hitters are obviously tapping into this source. If you are not a long hitter, ask yourself whether you are fully using the spinal twist in your golf swing.