"He sits in a car and he drives, that doesn't take being athletic," McNabb said Friday during a TV show debate on the most dominant athletes. "What athletically is he doing?"
It triggered an immediate backlash on social media against McNabb, who ranked Johnson third on his list behind Tiger Woods and Kobe Bryant. Fellow drivers rallied to the defense of Johnson, who stayed silent on the subject until Saturday morning.
Johnson tweeted his response, posting: "The debate continues … Everyone is entitled to an opinion. #DriversAreAthletes."
Johnson then headed off for the final two practice sessions before Sunday's season finale at Homestead-Miami Speedway.
He can win his sixth championship by finishing 23rd or better.
Johnson's 66 Sprint Cup wins since 2002 are 30 more than any other driver in that span, and a sixth title would put him behind only the seven won by Richard Petty and the late Dale Earnhardt.
Nationwide Series • Austin Dillon has won the NASCAR Nationwide Series championship, holding off Sam Hornish Jr. in a wild season finale Saturday.
Sprint Cup regular Brad Keselowski won the race after moving up 10 spots in the final few laps.
Dillon, driving the famed No. 3 for his grandfather, Richard Childress, held off Hornish by three points in the final standings.
Ford Ecoboost 400
P Sunday, 1 p.m.
TV • ESPN