Athletes with minor muscle, tendon, and/or ligament pain in their legs seldom want to be completely out of action. Although the pain may keep such stricken athletes from carrying out their full schedule of workouts, they still would like to do enough training to keep fitness at a high level. Unfortunately, this desire to 'keep on working' sometimes aggravates injuries, converting minor problems into serious ones.
The Orbiter 'soft-belt' treadmill is marketed as a device which helps with this problem, permitting athletes with leg pain to work at relatively higher intensities with less-than-usual discomfort, compared with running on regular treadmills or firm ground. To determine whether such claims are justified, researchers with the U. S. Army and at Baylor University in Texas recently studied 27 active-duty soldiers (14 male, 13 female) who were suffering from lower-extremity musculoskeletal injuries ('The Effects of Treadmill Type on Heart Rate, Pain, and Velocity Tolerance in Subjects with Lower Extremity Musculoskeletal Pain,' Journal of Orthopaedic & Sports Physical Therapy, Vol. 32(1), p. A-2, Abstract PL06, 2002).
The military subjects walked and ran on each of two treadmills (a regular, hard-belt treadmill and the Orbiter) at gradually increasing speeds until they experienced either the beginning of pain or an increase in pain from usual levels (the speed at which either of these events occurred was called the 'pain threshold velocity'). Running continued for two minutes after that point, during which heart rate and pain level were recorded.
As it turned out, the soldiers achieved a 10% higher heart rate with the Orbiter as well as a 15% higher pain threshold velocity, compared with the hard-belt treadmill. Thus, it appears that the Orbiter is beneficial, since it permits higher heart rates and higher running speeds to be achieved during workouts without increasing pain levels. Such effects should help hurt athletes maintain fitness more effectively, compared with running on a hard-belt mill.
Such a conclusion should be regarded with caution, however. Although the Orbiter pushed pain threshold velocity upward, it is not certain that it also controlled impact forces so that such forces did not increase significantly at the higher speeds permitted on the soft-belt device (actual impact forces were not measured in this research; impact forces usually tend to increase as a function of running speed). The use of the 'soft belt' on the Orbiter is no assurance that impact forces would be minimised, since research comparing soft-sole with hard-sole shoes does not always link reduced impact forces with the soft-sole ones.
In addition, there is always a danger that a device which wards off pain may encourage injured athletes to do too much training, ie, to train when they should be resting. In this light, it seems sensible to think of the Orbiter as a device which might be used to push up the intensity of sensibly planned workouts, not a machine which allows the piling on of large quantities of additional training. More research will be carried out with the Orbiter; it is a very intriguing device, and we will keep you posted.