Lying Leg Thrusts
We developed this exercise to counter the two main drawbacks of traditional Lying
Leg Raises lack of adequate ab involvement, and lower back stress.
Lie on your back on a soft mat or carpet. Place your fists under your pelvis on either side of your tailbone, palms down. the effect of this should be to keep your pelvis partially tipped up toward your stomach and your lower spine pressed against the ground.
Your lower back should be flat on the floor at the start of the exercise. Adjust your hand position to prevent your back from arching.
With fists supporting your hips, raise your head and shoulders, if possible slightly off the ground. To assume
this position requires abdominal strength and make the exercise harder. It will also make it virtually impossible for your back to arch, thereby guaranteeing maximum ab involvement.
If you're not strong enough to raise your head 'and shoulders, start gradually. Raise only your head and do a few reps. Five reps with good form is better than fifty without. Eventually, the strength will come.
Raise your legs about fourteen to eighteen inches off the floor-high enough that you can feel your lower back flat against the floor. Bend your knees slightly (Fig. 9-a). If you feel any tendency to arch your back, start higher and/or increase the bend in your knees.
Hinging at the waist, raise your legs and pelvis until your feet point straight up. At this point, thrust upward from your pelvis, as though trying to stamp your footprints on the ceiling (Fig. 9-b). Then drop straight down, retracing the upward path, and allow your legS to return to the starting position.
Each rep should feel like a two-part motion, an upswing and a vertical thrust. Keep the parts distinct: swing, thrust-then, coming down: drop pelvis, drop legs.