How to do the perfect plank

You may think that the core muscles are only the ones in your stomach. In fact, the core is made up of all the muscles that connect the upper and lower body, including those of the stomach, lower back, hips and buttocks. 
These muscles are essential for supporting the spine, aiding good posture, and almost every movement. By strengthening core muscles you will not only be on a fast track to a flatter stomach but will also improve the effectiveness of any exercise you do. 
The plank is one of the best exercises because it tightens the deepest core muscles. It's a static exercise where you use your arms to raise yourself off the floor and hold the whole body straight and rigid, like a plank of wood. 
You can do it anywhere, you don't need any equipment and it only takes a minute (literally). What's more, it is more effective than sit-ups and crunches because these work only the superficial abdominal muscles. 
Below are three different plank positions that target different core muscles. The longer you can hold a plank, the stronger your core will become and you will quickly see an improvement. 
Do not attempt the plank if you have suffered any lower back problems. 

1. BASIC PLANK

Start on elbows and knees, locking hands together. Straighten legs and raise your body so that you're supported by the balls of your feet, with feet hip-distance apart. Face the floor, being careful not to arch your back or stick your bottom in the air. Hold this position for 45 seconds to begin with, extending the time as you get stronger.

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2. SIDE PLANK

Lie on your right side, propped up on your elbow. Let your left foot rest on top of your right, and then push up so that your body forms a perfect triangle with the floor. Don't let your left shoulder roll forward or back. Hold the position for as long as you can, then repeat on the other side. 

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3. PRONE SKY-DIVE

Always follow a basic or side plank with this move. Lie flat on the floor, face down, with your arms by your sides. Gently raise your chest off the floor until you can feel your lower back muscles start to work, simultaneously raising your arms up, palms facing upwards and with your thumbs furthest away from your body, pointing to the ceiling. Be careful not to clench your buttocks. Hold for 30 seconds.