The Good Morning is an exercise to strengthen the muscles on the backside of your body, also known as the posterior chain. This exercise primarily targets your lower back and spinal erectors that work isometrically to keep the spine in an extended position, but it will also work your glutes, hamstrings, and upper back.
These muscles are involved in the vast majority of sports skills, such as sprinting, jumping, throwing a ball and others, so strengthening them is essential.
The good morning is a hip hinge exercise, meaning the movement comes from hinging your hips, or bending at your waist. It is very similar movement to the one done with deadlifts. The good morning is a great assistance exercise that will help you lift more weight with your squats and deadlifts.
The drawback is that when this exercise is done incorrectly, it might be one of the most dangerous exercises you can do. You're most at risk for an injury at the bottom of a rep when your torso is closest to parallel. In this position, the weight of the barbell places significant stress on your back. If you know how to properly stabilize your back, then it's not much of a concern. If your technique or strength is lacking, then it's a sure-fire way to injure your spine. Since correct form is so crucial, make sure to advice with an experienced trainer.
One of the biggest mistakes is to try to go parallel to the floor or even lower. This puts way too much stress on your lower back. instead, stop at about 20 degrees angle above parallel.
Keep your back in a natural position. This exercise is a hip hinge, means all movement is done by your hips not by your back. Maintain an arch in your lower back at all times. When you round your lower back with any exercise that places your back in a vulnerable position for injury. But when you keep your back arched it is in its strongest position.
Bend your knees and push your hips back a little. Doing the good mornings with straight legs will cause the bar to travel way forward, which will place a lot of unnecessary stress on the lumber spine. Just don't bend your knees too much, your legs should only be slightly bent.
Hold the bar on the traps and shoulders, not on the neck. This will give you more stability, and won't harm your neck.
Avoid craning your neck to look forward as you lean forwards. Instead, keep a neutral spine by looking forward on the same spot on the floor few meters in front of you.
Make sure you use a weight you can manage. If you are a beginner with this exercise, start with low weights and build up the weights gradually over time with progressive overload.
Your stance width can change the muscles being worked. A wide stance will focus more on the hamstrings and adductors. A narrow stance will put more emphasis on the glutes.