The Eli Manning appearance may make local football fans wince, but no one is likely to root against the cause he’s supporting.

Reebok International Ltd., the Canton maker of athletic shoes and apparel, is expected to say Friday it will donate $30 million during the next three years to partner with a nonprofit working to “solve the child obesity crisis.” The agreement with a Partnership for a Healthier America, will be unveiled in Washington, D.C. — where the group is based — at an event attended by first lady Michelle Obama, who is the organization’s honorary chair. Manning, the New York Giants quarterback and New England Patriots nemesis, will also participate.