Core Stability
Sit Ups are bad for your back? What? Yes, think of your back, especially your lumbar spine (low back), as a credit card. You can only bend that credit card forward and backward so many times before eventually it snaps. Sit Ups put excessive compressive loading on your spinal discs and can easily lead to disc bulge and disc herniation.
Rowers with no posture or core support end up bending from their lower back rather than pivoting from the hips, which leads to all the horror stories of slipped discs in rowing. Different coaches may or may not have you reach from the thoracic spine, but a common theme that any coach will agree with is keeping the lumbar region stiff, supported, and protected. Rowing is all about the legs after all!
That being said, without core stability it is impossible to transfer the force from your legs to the oar and move the boat at any type of speed. This idea of core stability and the ability to connect your feet to your hands through the core is a skill needed in life and fitness as well. There is no way to do an Olympic Lift like the Clean without having a solid core to work from.
From a leader in backs and biomechanics…
Daily Challenges for the Weekend!
5/4 – Complete 10 McGill Curl Ups.
Make sure to take at least three regular breaths on each curl up so that you’re not relying on your diaphragm and the inter-abdominal pressure created when you hold your breath. We want to work and strengthen our core stability. Share what you felt and think about the curl up!
5/5 – Complete 10 Bird Dogs.
Make sure to keep a neutral spine and continuously breathe. Imagine your back is a dinner table while you move through the bird dog. Don’t spill that home cooked meal on the floor! If it’s to easy try to draw squares with your hand and foot.
5/6 – Complete 10 Side Bridges (Hold for 10 seconds each side)
Ensure you keep the hip up and inline with your head and feet. Also, don’t break at the hip, you won’t be working those core muscles if you do. Instead think about gently pushing the hips forward and squeezing the glutes.
Renegade Rowing 
Situps bad for your back? but a necessity for bodybuilding……squats hurt too, also a necessity…
Perhaps situps are needed if your goal is bodybuilding, but there are better exercises like squats that can do just as much if not more to help us move our bodies, external objects, and boats…