Begin in plank position (see week 2), with feet hip-width apart and back straight. Keeping your right leg straight, sweep your left leg out to the side, tapping the floor with your big toe just below hip level. Return to start. Do 5 reps on each side. Repeat.
Lying on the floor on your back, with arms resting at your sides, raise both legs directly above your hips as high as you can. Bring your head up (but make sure you’re not putting a strain on your neck). Now with your stomach pulled in tightly, “flutter kick” your legs down towards the floor until your back arches. To vary it, you can cross your ankles, alternating one in front of the other. Bring legs back to the starting position and repeat 10 times.