In a previous post I briefly touched on how climate affects your game and ultimately your choice of strings.
Now that I am living in the heat I can give an account based on experience, both mine and the players I have being stringing for.
It's interesting how stringers opinions can differ when they come from different climates. Coming from Ireland, or other countries like Britain, where it's colder and people play all year round the recommendation of most stringers is that polyester strings are not for juniors.
Now it was recently pointed out to me that a racket strung with nylon at a high tension can be worse than one strung with polyester at a low tension, fair point!
My background as a fitness instructor would take into account the childs' muscular and skeletal development and how constant shock and vibration is not good for juniors, as their bodies can not absorb it like an adults. Add to that the colder weather and this vibration is amplified. So for Ireland at least, I am sticking to my 'NO TO POLY STRINGS FOR JUNIORS!
I will however use poly in a hybrid, especially with thinner gauge string and lower tensions. I believe this will give sufficient control for any junior (just to be clear when I speak of junior I am talking up to 14-15 years of age).
My own preference in strings, and I have tried a few, is a thick gauge multifilament at a high tension in the summer and lowering it during the winter months. However, since I have started playing in real heat I have found that, even at the higher tension, there isn't enough control with my multifilament string. I did try a couple of full poly strings in different gauges but found it too harsh on the arm for me. So I then tried the more common hybrid, that is poly in the mains and multifilament in the crosses. It was definitely better than the full poly option but still not what I was looking for.
It's worth noting when stringing as a hybrid that the main strings dominate the overall feel and playability of the racket.
So I then tried the 'Federer Hybrid' with the softer of the two strings in the mains and the stiffer one in the crosses, winner! I loved the feel of it straight away. It gave me more control than my full multifilament strings and was nowhere near as harsh as the poly dominated hybrid. It is definitely one I will be recommending for players looking for more control than their full nylon or multi can offer, and a setup I would also consider juniors.
If you are changing over from nylon or multifilament strings, I would recommend starting with a hybrid setup first and a thin gauge polyester. This will lessen the drastic change. If however you are going to change to full polyester then you should definitely use a thin gauge string and lower the tension. This will help with the power loss that you are going to experience.
So my conclusion for playing in the heat is that polyester strings are a necessity to some extent.
Higher temperatures cause the ball to move faster as the, heat softened, rubber core becomes more pliable and easier to propel.
For cold weather players, polyester shouldn't be your first choice. If it's control you are looking for, in these conditions, you should consider a thick gauge nylon or multifilament string. This will increase your level of control without sacrificing too much on the power front. Nylon and multifilament are softer strings and it is this elasticity that gives it the power. It also, during the winter months, makes it more comfortable on your cold arm.
Remember in colder climate the ball doesn't heat up as much, therefore it takes a greater effort to propel it. Also our body won't warm up as quickly so therefore the shock into your arm is amplified.
Regardless of what string you use, the very least you should be doing is changing your tension as the climate changes because the tension that gives you control during the hotter months will feel stone dead in the colder months.
High Tension = More Control
Low Tension = More Power.