"Exercise should be tailored to the individual," said Dr. Raymond Chong, an MCG assistant professor of physical therapy. An individualized approach is particularly important when developing an exercise program for someone with an injury or medical condition, as physical therapists routinely do, he noted.
Increasingly sophisticated tools are available to determine the effectiveness of exercises, and how appropriate they are for the individuals using them. Dr. Chong and four of his students used those tools this summer to study sit-ups from the inside out.
The group tested 15 healthy young adults performing six types of sit-ups: partial sit-ups (also called crunches, lifting the shoulders about six inches from a supine position) on the floor; full sit-ups (rising to a full lateral position) with knees bent at a 90-degree angle on the floor; crunches using an exercise ball with no assistance; full sit-ups using an exercise ball with no assistance; crunches using a ball held steady by an assistant; and full sit-ups using a ball held steady by an assistant.
In all positions, the study participants' arms were folded across their chest and their feet were stabilized. The exercise ball, a current trend in fitness, was soft, pliable and 70 centimeters in diameter. A metronome maintained a constant beat so that each sit-up was consistently timed.
The study participants did each type of sit-up eight times, with sensors attached that detected the electrical signals of each muscle contraction. The signals were fed into a computer so that the exact muscle activation of each sit-up could be measured and recorded.