[Gem]

If someone has pain in the back or anywhere else, that is the realm of professional allied health professionals such as physiotherapists and exercise physiologists.



For postural issues which are not painful or due to injury, a professional trainer who has specialised training in postural analysis and correction can assist with exercise programing.


Doing the wrong exercises can make posture worse, and also lead to injury. For example if a person has a hunched posture, then exercises involving hands directly overhead, such as that mentioned in the OP, or pull ups, or overhead lifts, are risky and will very likely lead to shoulder injuries.


Body weight squats are primarily a leg (quads) and glute exercise, and ineffective as a core strengthening drill. We have to consider a person's mobility capability when determining appropriate depth of the squat.



The bench press is a highly effective chest (and triceps) exercise, but it is a risky exercise that commonly leads to shoulder injuries. It needs to be performed with a correct, safe technique. It is a highly specialised lift.


When selecting exercises one has to balance out the risk to reward ratio, and select the exercises with the lowest risk with highest rewards (which is individualised).



The compound exercises (exercises which move through more than one joint) are the most effective generally speaking, and isolation exercises (only moving one joint) are not necessary, especially for beginners, but there is a place for isolation movements in more advanced exercise programs. For one example, a powerlifter might incorporate triceps isolation work if they are weak in locking out the bench press. The rear deltoids are also commonly isolated... I always include rear delt isolation work (though the drills I recommend move through both the shoulder and the elbow, so they are not isolation movements, strictly speaking).