Add Yahoo as a preferred source to see more of our stories on Google. So, while it's still important to have a well-rounded core routine (more on that below), the TikTok-ers are onto something: “If ...

• Sit-ups target your abdominal muscles, back muscles, and hip flexors, while crunches only target your abdominal muscles. • Neither sit-ups nor crunches alone burn abdominal fat. Overall activity and ...