Feedforward motor control in developmental dyslexia and developmental coordination disorder: Does comorbidity matter?

Cignetti et al. (2018) watched how kids prepare to move. They compared four groups: kids with both dyslexia and coordination disorder, kids with only dyslexia, kids with only coordination disorder, and typically developing peers.

Each child sat in a chair with a hidden motor that suddenly dropped their forearm. Sensors tracked muscle timing. The task shows how well the brain plans the move before it happens.

Only the comorbid group showed a clear lag. Their flexor muscles shut off late, so the arm dropped faster and they had to catch up. Kids with just one diagnosis looked like typical kids.

The delay points to a feedforward glitch: the brain sends the "get ready" signal too slowly when both conditions are present.

Schott et al. (2016) saw that DCD kids slow down when they walk while counting. Fabien shows the slowdown starts before the step: the plan itself is late. Together they map a timeline—poor anticipation first, then extra effort online.

Smits-Engelsman et al. (2023) later found that active video games boost balance in DCD. Their positive result seems opposite, but the kids trained anticipatory moves in fun drills—exactly what Fabien says the comorbid group lacks. The studies align: target the planning stage and gains follow.

Kaltner et al. (2014) linked dyslexia to slow mental rotation. Fabien extends that motor-cognitive overlap into real-time muscle control, showing the problem is not just in the mind—it reaches the arm.

If a child has both dyslexia and clumsiness, screen for feedforward gaps. Add quick, predictable unload games—dropping a light ball into their hand, catching falling beanbags—so they practice turning muscles off at the right moment. Five minutes at the start of sessions can sharpen the timing that paper worksheets miss.