Murray and Fallen Five
Injuries have sidelined six of the top players coming into the Australian Open. Each of them at their time seemed unbreakable in youth. Age does bring you down and heavy wear and tear can make it happen faster. I always expected Nadal and Murray to face injuries beyond most but especially Nadal. It is the nature of such a physical approach to the game and never giving up a point. Murray with his defensive approach until recently had similar problems. Once you lose your wheel (legs) in tennis your game is nearly done especially if your manner of play totally relied on court coverage.
Novak on the other hand is facing the other nightmare of a tennis player and that is a bad elbow. It can be a career ender. Ask Stolle, on of the greats from the 60's out of Australia. A shoulder injury isn't necessary a game ender because you usually feel it only on the serve and if your game isn't serve centric you can make adjustments though it's not ideal. A back injury seems like something that can come and go for tennis players and unless it hurts your mobility you can adjust your serve motion and rotation and stresses on it. Two handed players though seemingly tdo have an edge in power find back problems more difficult due to rotation and more stretching on wide shots. Whippy shots with heavy spin and wrist are almost a guarantee for eventual wrist problems.
Then comes the Federer. He deserves his own category as a function of nature as in then comes the cyclone. Yes, he has back problems now, and who doesn't at some point if you're an athlete. Yes, he hurt his knee outside the tennis court probably from underlying stresses that come with age. But overall, his magic is his smooth and effortless motion in court travel and strokes. He may come by it naturally but in some ways it can be shown that how you stroke the ball and when you learn to leave for a ball makes all the difference in how it stresses you. I'd take the Fed example and work towards precision and flow in both court coverage and strokes and you'll cut you injury rate.
Then there is equipment. I have to presume that some of the players use higher tension on their strings along with the string type that may cause issues with shock. But there is also the flexibility of the frame. If you use a very stiff frame the shock will transfer more readily to your arm and shoulder. Most power hitters seem to go with stiff frames. Consider going to a midrange flexibility on your frame with a 60 rating. I am at the low end with a 57 which offers lots of control and shock absorption and those that choose something with a 68-70 stiffness will feel more shock. Midrange stiffness might be somewhere around 65. YOu can find the stiffness ratings of your chosen frame online or on the frame if it is a more expensive racket.
Balance on the frame is a factor of your type of swing and so is the weight. I prefer the old style heavy frame closer to 12 ounces. That is very much on the high end nowadays I'll admit but looking at some of the pros I think many still go heavier than super light. Do your research and find something that can work for you over the long term. Oh, and consider the head size as your chance to make up for some timing deficiencies with a larger sweet spot that a 108-110 size head.
These pros have probably tried many of these things already but the fact is that once you reach such a high level of play it probably isn't wise to tinker with most of the variables like head size and stroke method. Sure, some get past it like Fed did with his racket change but it only came when he started struggling against other players who were younger, faster, and stronger. The bigger head size brought him back alive once he adjust his strokes for it.
Plan ahead and work your game, equipment, and practice methods to survive the long term. The pros you see out there winning are the ones that survived the cut of injuries. You often never see the ones that fell aside with injuries early in their careers.