The spine has a natural curvature in it in order to function correctly. With their attachment on the spine and pelvis, tight hip flexors can cause an unnatural curve of the spine called hyperlordosis. Hyperlordosis affects the way forces are distributed in the spine and can cause pain and soreness in the lower back. Other common problems that are associated with hyperlordosis are weak abdominal muscles, weak hamstrings, tight low back muscles, as well as tight hip flexors. This can lead to hip flexor and groin strains and hamstring strains…..an all around mess!
In contrast to strongman or powerlifting competitions, where physical strength is paramount, or to Olympic weightlifting, where the main point is equally split between strength and technique, bodybuilding competitions typically emphasize condition, size, and symmetry. Different organizations emphasize particular aspects of competition, and sometimes have different categories in which to compete.
Note that this recommendation is for total weekly volume, which means it would need to be divided up based on how many times you’re training each muscle group per week. So, for example, someone training everything twice per week would do 30-70 reps for each bigger muscle group in each of those workouts, and 15-35 reps for each smaller muscle group in each of those workouts.