Deadlifts begin with the barbell on the ground where the barbell is lifted vertically until lifter is in an upright position. The deadlift activates the posterior chain of the body.
Good mornings begin with the barbell on the upper back and the lifter slowly shifts his/her weight forward using a hip hinge movement. In this case, the horizontal motion activates the posterior chain of the body.
While belonging in the cluster of core compound exercises, deadlifts and good mornings have different mechanics, muscle activation processes, benefits, and risks.
Both the deadlifts and good mornings target the posterior chain of the body; They both activate the glutes, hamstrings, and the muscles of the inner thighs (adductor magnus).
The deadlift is a compound exercise that engages almost every major muscle in the body. It targets the core muscles, the lats and traps of the upper body, and the quads and hamstrings of the lower body.
Moreover, deadlifts have several variations which adjust the knee and back angle to emphasize a certain muscle or muscle groups.
While the conventional deadlift involves a normal shoulder-width stance with a slight knee bend and lifting the barbell to an upright position, a variation of the deadlift known as the sumo deadlift lowers the body by widening the foot placement.
By placing the feet slightly more than shoulder-width, the exercise becomes more reliant on the knees and therefore engages the glutes more than other muscles in the lower body.
To engage the hamstring muscles more, another variation of the deadlift known as the Romanian Deadlift (RDL) adjusts the back angle towards the ground to lessen the load on the glutes and transfer it to the hamstring muscles.
Good mornings were a popular exercise in the 60s and 70s before the popularity of deadlifts as a compound exercise. It also trains the glutes and hamstring similar to deadlifts. Good mornings are capable of isolating the hamstring muscles through their wide range of motion.
Good mornings have a greater effect on the posterior chain of the upper body. It is touted as one of the best exercises for training the entire back muscles. However, it also has been associated with risks of injury due to its mechanics.
The conventional deadlift starts with the barbell on the ground. The lifter lifts the barbell until he/she achieves lockout or the fully erect state and then either lets go of the barbell or slowly puts it down (maximizes the concentric benefits of the exercise).
At its core, the deadlift is simply picking heavy objects up and putting them down. Thus, the basic mechanics of the deadlift are simple and easy to follow, even for beginners.
Good mornings are a more complicated compound exercise. It involves placing the barbell on the upper back similar to squats and then leaning forward from the hips while flexing the hamstrings in the process.
It mimics a class 3 lever where the barbell functions as the load, the hips as the fulcrum, and the spine as the lever. It is called a "good morning" because it mimics the bowing motion used for greetings.
Good mornings are also hip hinge movements that rely on bending the waist to target specific muscles in the upper and lower body.
While the deadlift is a more vertical movement, good mornings are a more horizontal or forward movement. As such, the difference in bar placement makes the amount of weight used for good mornings much lighter than deadlifts. The shift in the center of gravity makes this exercise more difficult to maintain and balance than the deadlift.
Good mornings can also be performed without weights or with resistance bands depending on the goal and the experience level of the individual.
Sometimes, the weight of the bar itself is sufficient resistance. However, good mornings require greater mastery of technique, especially in terms of safety.
The deadlift is popular as a strength exercise used to increase muscle mass and overall kinesthetic performance for sports.
The deadlift is considered one of the most impactful exercises since it places significant amounts of stress on various major muscles in the body (central nervous system in general).
It also has hormonal and neurological benefits which help in tissue and muscular development (increased testosterone levels facilitates the release of growth hormones).
Good mornings help in correcting posture, building muscle, and increasing bone density around the spinal erector muscles which prevents back and spinal injuries.
Proper performance of good mornings can provide significant improvements on core strength as well as lower back and hamstring development. It also provides sport-specific improvements such as positional strength for performing clean and jerk and snatches when weightlifting.
However, the good morning carries a greater risk for back injury when performed improperly or excessively. As such, this exercise is usually performed only with light/medium weight and with a full range of motion.
Deadlifts and good mornings both target the posterior chain of the body. However, the squat-like nature of the good mornings activates the posterior muscles differently than deadlifts and their variations.
Good mornings target more of the upper posterior chain while deadlifts target more of the lower posterior chain. The priority of good mornings in training the upper posterior chain, specifically the back and spinal muscles, means it carries greater risk and should therefore be performed safely with mastery of technique.