Planks are billed as the must-do ab move if you're serious about developing a strong core. While the plank, and its numerous variations, are excellent at training your core in a functional way — assisting with stability, posture and spinal alignment — the move alone will not give you a six pack. Diet, total-body strength training and cardio exercise are also required to develop visible abs.
Read more: 3 Cardinal Rules of Fast Six-Pack Abs
The Plank's Proven Benefits
Research stands behind the plank as a move that effectively strengthens the muscles of the abs. The forearm plank stimulates the ab muscles of the rectus abdominus and external obliques far more than a traditional crunch, noted Pennsylvania State University researchers in an issue of Medicine and Science in Sports and Medicine published in 2011.
When you get into the plank position, your entire core engages. The move requires stabilization and muscle activation of not only the abs but also the muscles of the middle and lower back, pelvis and hips. Crunches and situps focus effort only on the rectus abdominus — the front sheath of abs — and miss many of these other crucial parts of your core.
Unlike crunches and situps, which put stress on the vertebrae as you push your back toward the mat to curl up, planks keep the back in its intended alignment. You'll also be less likely to cause stress on the neck by pulling on it to curl up. Planks are modifiable by placing your knees on the floor to provide some support for your trunk when you're first starting out.
Build on the Plank
Working up to holding a plank for 30 to 60 seconds provides you with a foundation of strength in your abs. But, holding the position for longer doesn't necessarily bring about greater benefits.
A body that's strong in plank is ready for added challenges and needs them for continued improvement in core strength and ab development. Perform plank on an unstable surface, such as a stability ball or balance disc; hold a plank with one leg lifted; perform one-armed planks; balance in a one-armed, one-legged plank; and add side plank.
Once you've mastered plank, it serves as an exceptional warmup to make your body strong for other abdominal exercises that further develop a strong, supple core.
Plank Alone Won't Develop Visible Abs
A strong core derived from regular planking isn't necessarily a sculpted one. If you have a layer of fat padding the muscles, your abs will never show. You need to be lean — about 6 to 9 percent body fat for a man and 16 to 19 percent for a woman — to reveal developed abs.
To reduce body fat to these levels, a portion-controlled diet that emphasizes whole foods and specific ratios of carbohydrates, protein and fats must be followed. Regular cardiovascular exercise — usually 30 to 60 minutes daily — and some at a high-intensity and total-body strength training three or more times per week are other key strategies.