Polyester String
Also known as: poly string, co-poly, polyester co-polymer, poly
Polyester string is a stiff, low-elasticity monofilament string that provides superior spin potential and durability but transmits more shock to the arm compared to natural gut or multifilament strings.
Polyester strings became standard in professional tennis through the 1990s after Pete Sampras's competitors discovered they could generate heavy topspin while maintaining string-bed control. The key properties are stiffness (low elasticity), which gives a dense snap-back effect that bites the ball and produces topspin, and durability, which withstands the sustained friction of topspin swingers. The downsides are significant: polyester loses tension rapidly (often 10–15% in the first 24 hours), reducing its performance properties, and it transmits substantially more shock and vibration to the elbow and shoulder than softer strings. Players with arm injuries are often advised to avoid poly or use it only as a cross string in a hybrid setup with natural gut mains. Full polyester setups are most appropriate for young, physically robust players who swing fast enough to activate the snap-back mechanism.
Example
A competitive junior uses full polyester at 50 lbs for heavy topspin and control but develops tennis elbow within a season — the coach switches to a natural-gut/poly hybrid to reduce arm stress.
Why it matters
The right string can amplify your swing mechanics. SwingVantage notes that equipment choices matter most when mechanics are already sound — optimizing strings on a flawed swing produces minimal returns.
Frequently asked questions
Is polyester string bad for my arm?
High-stiffness polyester at high tension increases arm stress. If you have any arm discomfort, reduce tension, use a thinner gauge, or try a hybrid setup with natural gut mains.
Related terms
- Natural Gut StringNatural gut string is made from cow intestine and offers the highest elasticity, best tension retention, and greatest comfort of any string material, at a significant cost and durability trade-off.
- String TensionString tension is the tightness at which strings are pulled through the racquet frame, measured in pounds or kilograms, influencing the trampoline effect, control, and power of the string bed.
- String GaugeString gauge is the thickness of a tennis string measured in millimetres or gauge numbers, with thinner strings providing more spin and feel and thicker strings offering greater durability.
- Vibration DampenerA vibration dampener is a small rubber or silicone device inserted at the bottom of the string bed to reduce the high-pitched "ping" vibration and change the sound of the racquet at contact.
- TopspinTopspin is forward spin imparted by brushing up the back of the ball. It makes the ball dip down into the court and kick up high after the bounce.
Related guides & benchmarks
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