The Dolphins are doubling down on running back additions in the wake of Alexander Mattison's season-ending neck injury.

The Miami Dolphins signed two free-agent running backs following the injury to Alexander Mattison, who is out for the season.

Free-agent running backs Mike Boone and Aaron Shampklin have signed contracts with the Miami Dolphins. The Dolphins wasted little time beefing up their running-back corps after they lost Alexander ...

With Alexander Mattison done for the season, the Dolphins are adding some running back depth. Read PFR for more.

In the wake of losing Alexander Mattison to a season-ending neck injury, the Dolphins moved quickly to add running back depth Monday, signing veterans Aaron Shampklin and Mike Boone. To make room on ...

The Dolphins signed Boone to a contract Monday. With Alexander Mattison (neck) being placed on injured reserve, the Dolphins bolstered their backfield Monday by adding Boone and Aaron Shampklin. Boone ...