I have taken a close look at the research on racquet science, and a few key terms seem to be related to how we acquire injuries directly from playing with certain badminton racquets.
The first term that came up was work. Work is the energy required to produce a certain shuttle speed. It measures the efficiency of the badminton racquet. The more efficient your badminton racket is, the less work you need to put in. So a low work racket is good for you. A high work racquet is bad because you have to put in more work to achieve the same shuttle speed. Think of work as the rackets power.
Another key term is shock, which is the loading of the racquet from a sudden change in kinetic energy. It relates to how much the racket slows down on impact with the shuttlecock. After impact energy is lost, the shuttle gets some of this energy, and the rest is used in bending the frame. If the frame is very stiff, it will not absorb this energy, instead, it will be dumped into your arm. High shock is bad for injuries.
The research has proved that the best type of racquet to use to attain maximum power is one that is heavy with a head light balance. More mass placed close to the handle allows makes it easier to swing. More mass placed at the tip makes it more difficult to swing. Think of how hard it is to swing a sledgehammer, with all that weight placed at one end. Now, if you hold the sledgehammer with the weight placed in your hands, it is much easier to swing.
There are two schools of thought involving weight. Some argue that a light racket will allow you to swing faster, and therefore create more velocity on impact, resulting in faster shuttle speed. The other side of the argument is that a heavy racket will have more mass on impact, despite less swing speed, and this extra weight will create the necessary shuttle speed. However, momentum is what counts in a collision.
The lightweight racket will slow down much quicker after impact, putting more stress on your shoulder. You have to put in more work to get the shuttle speed with light racquets. Faster swing speed means less control. Over time this lightweight racket will demolish your arm compared to a heavier one. The heavy racket will not slow down as much after impact, and so less strain is placed on you.
The modern trend in all racket sports is to have light rackets with a head heavy balance. At first glance it seems this is a good combination to create power. More mass at the top will help the racket to crush through the shuttle on impact. However, more mass at the tip makes it more difficult to swing. Remember the sledgehammer example? It requires more effort on your part, you have to work harder to achieve the same shuttle speed as a heavy, head light racquet. Also, head heavy rackets feel sluggish and slow.
Here is the low down… Head light and heavy is best for performance, and best for avoiding injury.
As an example i have looked at the balance and weight specifications for the most popular badminton manufacturer, Yonex. Not one Yonex model has a head light balance, many of them are head heavy such as the muscle power series, whilst the nanospeed series appears to be slightly head heavy. What makes these rackets even worse for injury is that many of them have stiff frames, which increases vibration.