2 Plank Variations to Build a Strong Core

While the appearance of lean abs is appealing to the eye, the strength and functionality of the core is even more important. A strong core will allow you to perform all the household, leisure or sport activities safely.
More: 5 Reasons to Strengthen Your Core
Strengthening your core does not mean that you just train your abdominals to get them to look pretty. The "core" means everything in the center of your body, such as the abdominals, obliques, and the lower back.

You can strengthen each muscle group separately, but ultimately, the best and most functional way to strengthen your core is to do exercises that work everything in unison—all your body parts move at the same time.
One of the best exercises to strengthen your core is the plank.
More: Master the Plank 

Plank

Get down on the ground on your hands and feet. Align your shoulders over the hands and spread your fingers wide, pointing forward. Keep your both arms symmetrical and straight. Your lifestyle creates many imbalances in your body. During your fitness training always be cautious of your posture so you will not add more imbalances. Maintain your body straight like a plank, with the hips 1 inch above the line linking your feet and shoulders. Engage your abdominals at all times and breathe deeply. Hold this position for one minute and over time increase the interval until you can do two minutes without rest. That is a sign of strong core.
More: 5 Ways to Perfect Your Plank
As you get tired, the hips want to sink lower. You have to stop them so you don't put excessive pressure on your lower back. If your body starts shaking, continue breathing and try to relax. Relaxing while your muscles are under tension is not easy, but it is a good practice for life.
If you feel discomfort or pain in your wrists, perform the plank on your elbows instead.

Plank with Opposite Arm and Leg Lift

When the simple plank is not challenging anymore, you can add difficulty by simultaneously lifting one arm and the opposite leg off the ground.
More: 4 Ways to Build Balance
Get your balance first, breathe in, and lift your both limbs up, parallel to the ground. Keep them straight and try to elongate your body as much as possible. Hold the top position for two seconds. If you lose your balance temporarily, try to regain it before you switch sides in a controlled manner. Repeat slowly 20 times.
More: Tone Up With Plank Pose
Plank with opposite arm and leg is very challenging, but is excellent to strengthen your core, shoulders and hips. Additionally, it improves your balance, coordination, and patience—important elements in your daily activities and life in general.