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Step 1: Duplicate your video layer
Hold Alt (Option on Mac) and drag your clip upward to create a copy on the track above, then select the top copy. You will mask the muscle on this layer, so the clip below keeps the full picture.
Step 2: Draw a mask around the muscle with the Pen tool
Open Effect Controls and scroll down to Opacity. Click the Pen tool (Free draw bezier) below it. Then click around the muscle in the Program Monitor to create points. If you hold the left mouse button while you place a point, you can drag to curve the line, which is useful for rounded shapes like a biceps. Zoom the monitor in first so you can place points accurately.
Step 3: Track the mask
To make the mask follow the muscle, click the Track selected mask forward (play) button next to Mask Path. Premiere Pro now tracks the muscle automatically, one frame after another.
If the mask starts to drift, stop the tracking and fix it. A good habit is to use the Track selected mask forward 1 frame button, check that the mask still sits on the muscle, and only then continue. You can always go back, adjust the mask shape, and let Premiere Pro overwrite the keyframes from there.
Step 4: Create a color matte
When tracking is finished, only the muscle should show on the top layer. Now give it a color. Right-click in the Project panel, go to New Item > Color Matte and pick the color you want, such as a bright red, then click OK. Drag the color matte onto a track above your clips.
One click with Mako: the free Mako panel adds a color matte over the selected clips, at the playhead, on the first free track, in one click. Get Mako for free
Step 5: Copy the mask onto the color matte
Select the video layer with the tracked mask, open Effect Controls and click the mask name under Opacity. Press Ctrl + C. Then select the color matte, click Opacity in its Effect Controls and press Ctrl + V to paste the mask. The color now appears only on the muscle. You can delete the second video layer, since the color matte replaces it.
Step 6: Blend the color with the muscle
A flat color looks fake, so select the color matte and change Blend Mode in Effect Controls to something like Overlay. The color now picks up the shadows and highlights of the muscle, which looks much more natural.
Step 7: Fine-tune the look
A few extra settings make the highlight look better:
- Fade in and out. Add keyframes to the matte's Opacity so the highlight fades in and out instead of appearing suddenly.
- Change the color. Double-click the color matte in the Project panel and pick a different color.
- Soften the edge. Raise Mask Feather to smooth the mask, and adjust Mask Expansion if the highlight is too small or too large.
Smoother with EaseFlow: select the opacity keyframes and apply a real easing curve in one click instead of dragging Bezier handles, so the glow fades in and out softly. See EaseFlow
FAQ
Why does the mask lose the muscle while tracking?
Fast movement, motion blur or a change of angle can confuse the tracker. Stop tracking, fix the mask on the current frame and continue, or track one frame at a time in tricky sections.
Can I highlight more than one muscle?
Yes. Repeat the process on a new copy of the clip, or add a second mask to the same layer, and use a different color matte for each muscle.
Which blend mode looks best?
Overlay is a good start because it keeps the muscle's texture. Try Soft Light for a subtler glow or Screen for a brighter one.
Want to make the highlight glow even more? Try the free glow presets.
