Please take a second to let your arms hang down. Now look at how your palms are rotated. Most probably they are facing each other. This is called the neutral grip position. In fact, this grip as well as a rotational arm movement from the pronated towards the supinated position constitutes our body's most natural range of motion.
The problem:Most types of deadlifts, rows, pull-ups and other fundamental pull movements aren’t performed in those grip angles which, according to science can lead to shoulder, wrist and elbow injuries. But that isn't all.
Your muscle growth is going to suffer too, since you are not training at angles that engage your back and shoulders most efficiently. In addition, by always choosing the same training positions, you will only activate those same muscle fibres over and over again.