It's not uncommon to see bodybuilders with weak core muscles and it's very obvious that their lack of strength in those important stabilizing muscles ultimately reduces the effectiveness of their workouts. (fitnessandpower.com)
Sitting for hours at a time can cause havoc on your abdominal region including not only weight gain but also weak core muscles and back problems. (fitbodyhq.com)
Can weak core muscles affect your hamstrings? (cathe.com)