When it comes to planking, many people tend to focus on their form and forget about the small details that can make a big difference. One of those details is keeping your body still while you plank. Shaking or trembling while planking is completely normal, but there are a few things you can do to minimize it.
Start by lengthening your spine and engaging your core muscles. Tuck your chin slightly and gaze at a spot on the ground about a foot in front of you. Keep your shoulders down and away from your ears, and press firmly through your palms into the ground. As you exhale, imagine drawing your belly button back toward your spine. Hold this position for as long as you can without allowing your hips to drop or arch.
If shaking starts to occur, try pressing more firmly into the ground with both hands and really engage those core muscles. If that doesn't work, try doing a one-arm plank: place one forearm on the ground so that your elbow is directly under your shoulder, then stack the other hand on top of it and press down into the ground just as before. Planking on one arm challenges our stabilizing muscles even more than two-arm planks, so this is a great way to really work on those key muscle groups needed for a strong plank hold!