July 30, 2008
Weekly News UpdateJoint and Muscle Impact Reduced by Low-Gravity Training Machine
Research conducted by Dr. Rodger Kram of the University of Colorado at Boulder indicates that a space-age, low-gravity training machine reduces the impact on runners' muscles and joints by 50 percent. Kram, an associate professor of integrative physiology, coauthored the study with Alena Grabowski, a doctoral student at CU-Boulder at the time of the study. The results of their study were published in the August issue of the Journal of Applied Biomechanics.
The scientists based their research on the use of the "G-Trainer," a machine that is made up of a treadmill surrounded by an inflatable plastic chamber that encases the lower body of the runner. Air is pumped into the plastic chamber, which increases the pressure and therefore effectively reduces the weight of the runner, who is sealed into the machine at the waist. The technology behind the G-Trainer was originally developed by Rob Whalen, a researcher at NASA's Ames Research Center in California. NASA was interested in the technology as a way to help astronauts maintain their fitness while in space. The technology developed by NASA was used to help astronauts effectively increase their weight while in low-gravity situations to prevent muscle atrophy and bone loss. The G-Trainer, however, reverses the process.
For their study, Kram and Grabowski modified the G-Trainer by exchanging a standard treadmill for a treadmill that measured force. The modified treadmill measured the biomechanical forces on the subject's legs during running by charting the vertical and horizontal stress load on each foot during locomotion. The study included ten subjects. Each subject ran at three different speeds at a variety of reduced weights for a period of seven minutes. In addition to measuring the forces on the subject's legs, the researchers also measured the subject's oxygen consumption during their runs.
The researchers found that a subject running at half their weight on the G-Trainer decreased the "peak" force absorbed by their joints from their heel striking the treadmill by 44 percent. These results are significant given that when running in a normal situation, a runner's joints absorb a force equal to double the runner's weight each time their foot strikes the ground.
According to Kram, the results of the study have implications for both competitive runners recovering from injuries and for normal people recovering from hip or knee surgeries. Several Olympic-bound and other competitive runners already use the G-Trainer as a part of their normal training routine. Training on the G-Trainer allows healthy runners to prevent injuries while still getting in the necessary workout.
"We showed that a person can run faster in the G-Trainer at a lower weight and still get substantial aerobic benefits while maintaining good neuromuscular coordination," Kram said.
A follow-up study is in the works to research the use of the G-Trainer with walkers. Kram and Grabowski hope to learn how effective the G-Trainer would be as a rehabilitation device for those recovering from surgeries, stress fractures, or other lower body injuries.