By 2018, the number of physical therapists in the United States is projected to grow by 30.3 percent, but the number of students majoring in kinesiology – a field in which many physical therapists hold a degree -- is growing at an even faster rate. According to the American Kinesiology Association, the number of undergraduate kinesiology majors grew 50 percent from 2003 to 2008, to more than 26,000 students, making it one of the fastest-growing majors in the country.