Exercise #2: Long-lever crunches on the BOSU
Reps: 10 per side
Lie on your back on the BOSU ball so that your lower back is supported. Reach your left arm over your head and extend your right leg. Pull your abdominal muscles in and do a stomach crunch up so that your left hand touches your right shoelace. Try to keep your legs as straight as possible so that you're also stretching out your hamstring muscles. Complete 10 reps, then extend your right arm and left leg and repeat on the other side. Do two more sets of this.
Modification: Decrease the length of the levers either by bending your knees to a 90-degree angle or putting your hand gently behind your neck.
Advancement: Add a small hand weight into the exercise. Start with 3 pounds and go up from there.
Tip: If this exercise is hurting your lower back, then you're probably arching your back instead of letting it be fully supported by the BOSU ball. Try to decrease the distance between your belly button and your ribcage (i.e. pull in your abdominal muscles) to correct this.
Exercise #3: Bridge Marching on the BOSU
Lie on your back with your feet on the dome side of the BOSU and your bottom roughly 6 to 9 inches away from the base. Lift up into a bridge, engaging your hamstrings, lower abdominals and glute muscles. Once you feel stable, slowly lift your left leg up to a 90-degree angle. Hold for one count and then place it back onto the BOSU ball. Lift your right leg up and slowly lower it down. Continue this for 10 reps per side before lowering down. Repeat this set two more times.
Modification: Do this exercise on the ground without the BOSU ball.
Advancement: Hold two dumbbells, one against each upper thigh to recruit extra weight into the exercise.
Tip: Make sure your hips aren't dropping to one side or another as you march. This is a good indication of a muscle imbalance from one side to the other. Imagine each of your hip bones has a headlight shining straight up from it, and try to keep the lights straight.