Straight-Arm Plank on Balance Board
Begin by kneeling on a mat with your knees together, hands on top of a balance board, and arms directly beneath your shoulders (not pictured). Extend one leg at a time until you are balanced on the balls of the feet (pictured). Make sure your abs are engaged and your body forms a straight line from the shoulders to the hip, knee and ankles.
Breathe steadily as you hold this plank position for 15-30 seconds. Gradually work your way up to holding the plank for 1-3 minutes for an isometric core challenge.
Don't let your hips drop or rise, and be sure not to shift weight to one arm. Hold your body as still as possible and try to keep the balance board steady, too. Remember to breathe.Muscles Worked: Abs, Lower back