Other athletes, including Joaquim Cruz and Ben Johnson, expressed disbelief over Griffith Joyner's dramatic improvement over a short period of time.  Before the 1988 track and field season, Griffith Joyner's best time in the 100-meter sprint was seconds. In 1988, she improved that by seconds (or sec for the non-wind-aided time). Similarly, her best before 1988 at 200-meters was seconds. In 1988, she improved that by seconds to seconds, another time that has not been approached. Griffith Joyner attributed the change in her physique to new health programs.  Al Joyner replaced Bob Kersee as her coach, and he changed her training program to include more lower body strength training exercises such as squats and lunges.