Workouts without equipment are mostly consider useless for muscle growth but if they are performed with correct technique and intensity they can help you to gain strength. Lower back is the main muscle involved in squats and dead lifts. Without stronger lower back you can not lift heavy weight when your back gets involved in any kind of workout.
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Lower back however can not support your body unless it is supported by strong glutes. Angel of Death workout is best exercise that require the combine effort of your glutes and your back. To involve both parts you need to lift both your toes knees and your thighs above the ground. You need to move your hands from the over head position all the way to your sides.
