These two exercises work your core, obliques, wrists, shoulders, biceps and glutes. They are two very effective and challenging exercises.
The first side Plank exercise
Position yourself in a side plank and as you press the dumbbell over your shoulder lift your leg at the same time. Hold and lower back to start position. If this is too hard do it without the weights. Do 2-3 sets 8-12 reps on each side.
Second Plank exercise
Position yourself in a side plank and swing the dumbbell under your body and then back out infront of you. Again if this is too challenging do it without the weights and come down onto your elbow. Do 2-3 sets 8-12 reps on each side.