Mark Martin will feel his age in the morning or a day or two after a race. His bones will stiffen and his body will ache after driving 400 grueling miles, even though the fitness fanatic is still in top shape. After all, 50 is 50 and that matters well, everywhere but on the track. Martin is still nifty at 50 and has made Cup racing his personal senior circuit. He won at Chicagoland Speedway, getting the strong jump off the double-file restart with two laps left to win his series-high fourth race of the season.