As spinal flexion exercises increase in speed, there's an increased risk of compensation. And this compensation may place unwanted stress through the lower back and posterior pelvic girdle.
The most effective way to maximize full body tension is to slow down the speed of the movement and accentuate the tempo. This will increase stability throughout the shoulders, core, and hips.
People are familiar with slowing down the eccentric or lowering portion of a lift to maximize time under tension, but what about the concentric or lifting portions? Both can be manipulated to make spinal flexion safer and more effective.
Here's what to do: Move slowly into a controlled range of spinal flexion, then strategically lower under perfectly controlled multi-joint stability. You'll reduce lower back flare-ups and build a strong core.
Start with a 2-3 second concentric (lifting) portion of a crunch-based movement, and lower with another 2-3 second descent. Do it right and it'll take you anywhere from 5-8 seconds to do a perfect rep.