What is Pre-Stretching, how is it done,  and what does it do?

What follows is a brief, limited, and non-technical explanation.  

• Pre-stretching is simply applying tension to the entire length of a tennis string.
• The best Pre-stretch is a tension of 25-30 pounds for 30-35 seconds.
• Pre-stretching stabilizes the string and reduces short-term creep (tension loss).

Over the years, especially in the last decade, concerns have been raised about the potential damage pre-stretching can cause to certain string materials, mainly polyester.  We have found that this is not the case, and most strings, including polyester, benefit from a well-done pre-stretch.

Two material properties important to this discussion are elasticity and elastic limit.

• Elasticity, a fundamental material property, refers to the string’s ability to return to the original length after applying a load (tension).  Understanding this concept will give you insight into the string’s behavior.  An Elastic Limit is when the string has passed the point of no return…in other words, the string has been stretched too much and will never return to anything close to the original length.  When the string has reached this spot, it has entered the “plastic” (opposite of elastic) stage.

We test every string for several properties, one of which is UTS, Ultimate Tensile Strength, which ranges from 120 to about 200 pounds.  Not once have we experienced the string reaching the elastic limit before failing!

When pre-stretching is properly administered, it poses no danger to the string.  

Pre-stretching offers numerous and significant advantages. These include better tension retention, stability, consistency across the string bed, and ease of handling a string with a high recoil memory.

As a player, you can ask your racquet technician to use or not use pre-stretch.  It should be your decision based on performance and benefits.

It won’t hurt the string!