When words are stored in the brain, they are stored in complex ways - as verbal definitions, visual pictures, sounds, personal contexts and emotional associations, and as movements. When we gesture, this study below finds that the movements help speakers retrieve words. If you stopped the movements, you stopped fluency. Another interesting tidbit that turned up, people tended to gesture more when their were trying to describe a visual pattern that wasn't easily named (drawing with their hands) and objects that you could touch or manipulate. They speculate that when we learn about tangible objects, we register our knowledge and memory of that with sensory/motor memory as well as with words or sight.
All this implies that language learning should be a vivid affair. So go ahead and add drama to your family or classroom readings - may a bold sweep of gestures and accentuate your voice. This is really multisensory language - language that is sound, music, rhythm, movement, visual, and emotive...much more than words only.
Another rumination on this work is that folks with with sensory-motor challenges are disadvantaged if they don't have 'in sync' sensory-motor / movement systems as the learn and use words. In the optimal state, many large scale brain networks work in integration with each other. There may be surprising other consequences when one system becomes impaired.
Gesture and Language pdf