Sideliner

The result is more dissent because successful collective action sustains the involvement of old participants while convincing sideliners of the usefulness of protest and ensuring their future participation […]

It’s a bold statement (not to mention a cliché), but Mr. Cardiello, who created this high-energy workout to bring football to sideliners, isn’t afraid to be bold: he is a private trainer for N.F.L. players and former conditioning coach in the Arena Football League.