Natural gut has survived the polyester era on comfort alone

An expensive string made from cow intestine still appears in the frames of top professionals, and the reason is the elbow.

It is an odd fact of a technology driven sport that the best feeling string available is made from a serosa layer of cow intestine, cut into ribbons, twisted, and dried. It has been in use for over a century. It costs several times what a set of polyester costs, it hates moisture, and a rain delay can effectively ruin a string bed. It is still in professional frames every week.

The reason is not power, although gut has plenty. It is the combination of elasticity and tension maintenance. Gut stretches a long way under load and returns almost all of that energy, which means the string bed does more of the work of the impact and the arm does less. It also holds its tension far better than polyester does, so the fiftieth game feels close to the first. Poly gives you spin and control and durability and gives back a harsh, quickly dying string bed that transmits shock into the forearm.

Which is why the common professional setup is a hybrid rather than either extreme. Gut in the mains, running the length of the frame where the stretch does most for comfort and power, poly in the crosses for the bite and the durability. It is a compromise that gets a large share of both benefits, and it is more or less the standard answer for players who want spin without an elbow problem.

The reason I raise it is that amateurs have the opposite arrangement, and it makes no sense. The professional plays with a full poly bed for a day and replaces it. The amateur strings full poly and plays it for six months, which means they spend the overwhelming majority of their tennis on dead string that stopped moving weeks ago. That player is not getting the spin benefit, because a dead poly bed does not grip. They are getting the harshness, all of it, and then they blame the racquet.

Gut is expensive and it dislikes rain, and a full gut bed on a heavy topspin player will not last a weekend.

But if your elbow hurts and your strings never break, the string is the first thing I would change and the last thing anybody ever does.