Which tension is best?
Moderate tension (40 to 50 lbs.) offers more comfort, spin and power. The flip side is that you'll have less control and accuracy.
High tension (>50 lbs.) provides greater control and accuracy. It can, however, lead to tendinitis. You will also have less spin and power.
About monofilaments
For monofilament strings, Decathlon recommends a tension of between 42 and 49 lbs. We strongly recommend against using monofilament strings for children under 15 to avoid injury. These strings are best for players who break strings in under 10 hours of play because they quickly lose their tension (20% loss within 3 hours of play).
When should you change your strings?
For multifilament strings, Decathlon recommends a maximum tension of 55 lbs. These strings are recommended for people who are prone to tendinitis, youngsters, and people who don't break their strings often. Multifilament strings keep their tension very well and stay bouncy longer.