Research shows that people who suffer from spine conditions such as spinal stenosis (a narrowing of the vertebral lumen), disc bulging, or herniation should not do crunches," says Linda LaRue, RN, certified personal trainer and creator of the Core Transformer.
The horizontal squat may not be a well-known exercise, but "it's a great move that works your entire core three-dimensionally and involves acceleration and deceleration (most sports injuries happen when you're decelerating). You can also progress this move by adding a side plank or mountain climbers at the end," LaRue says.
To do the horizontal squat (pictured), start on hands and knees, keeping belly button drawn into spine and holding a constant kegel (the same feeling as holding in urine when you really need to go). Lift knees off ground slowly, shifting weight into legs, sitting back into hips as if doing a squat. Quickly drive body forward, extending legs into the top of a pushup or plank position. Hold this pose for 2 seconds, keeping head stacked in a straight line with hips, knees, and ankles. Keep shoulders down and stacked directly above hands.