String "Timing"

Being a former high string tension user myself, I now advise others to string as low as they can still control the ball with.

By high-tension in today's viewpoint, I mean 60 lbs and above with full poly or most poly hybrids.

Dropping tension has more advantages than disadvantages. While not everyone would be able to adapt, most should find no big problems, with only slight changes in their swings. 

With full permission from this chap I have been speaking with, I reproduced below what I thought was an interesting myth regarding tension and accuracy. Let's call him "K".

For as long as I can remember, K has been stringing his 16x19 stringbed with full 16g poly at 68 lbs. K is a strong guy. He hits hard and snaps thinner poly strings frequently.

Like many hard hitters, K prefers his stringbed as dead and as low-powered as possible. He believed in minimizing all power variables and allowing himself to be the sole power generator. Thus maximizing control and accuracy.

We couldn't find any paper with us, hence we drew on the back of an envelope...

Below is a graph depicting string "Pocketing Depth" vs "Time". Time "0" is when ball impacts stringbed.

"A" is a soft string, like natural gut or multifilament.
"B" is a stiff string, typically poly.
Both "A1" and "B1" show the respective string's rebound after it has lost tension. 

So, when freshly strung, the softer string "A" offers more pocketing than the stiffer "B". As a result, the dwell time, or how long the ball stays on the string, is longer for "A" and shorter for "B" too. This is true even after "B" loses tension to become "B1".

In K's opinion, the shorter the dwell time, the better. 

If you refer to the bottom half of the above drawing, it shows a right-hander hitting a ball with a racket. The contact point is "X", and "Y" is the point where the ball leaves the stringbed. So the time between "X" and "Y" is the dwell time.

K's argument was, since the ideal ball impact location is way in front of our body, a long dwell time would mean the ball leaving the strings too late. By then, the racket face would have rotated inwards. The shot would go left instead of straight.

That was the only complaint K had.

So I did some simplified calculations with him to prove my point:

Average dwell time generally accepted: 5 milliseconds
K's fastest swing speed: 78 miles per hour
5 ms = 5/1000 second = 0.005 second
78 mph = 124.8 km/h = 124800 m/h = 2080 m/min = 34.67 m/s

So, during the duration of the 5 ms dwell time, based on K's swing speed, his racket would have travelled a distance of:

34.67 metres per second  X  0.005 seconds
= 0.17335 metres or 17.335 cm or 6.82 inches

My point is, all K needed to do, was to chase the ball forward with the racket, or even upwards for topspin, after impact.

6.8 inches is slightly less than the diameter of three tennis balls. Perhaps that's why coaches keep barking:

"Hit through the ball"

"Visualize hitting through 3 or 4 tennis balls"

Whether it is a string tension problem, long dwell time problem or swing timing problem, I left it for K to mull over.