Every few weeks, someone will tag me in a Facebook thread where people are arguing about the negative effects of sit-ups or crunches on posture. Typically, someone will claim that people are already sitting all day long and then question why would we dare put them into flexed postures during their training. They’ll also claim that performing sit-ups or crunches leads to negative postural adaptations such as kyphosis and forward head posture.
Trust me, I understand the sentiments. On weekends, when I don’t train myself or any clients, I tend to sit for much of the day trying to catch up on reading and writing. I can certainly feel the effects of such sitting on my body. Do this day in and day out, and I’m certain that it will have a negative impact on posture and function.