Basically, those that arise from the related phenomenon of gravity, load bearing, and exertion. CADS are effective bionics because they reduce perceived gravity, assume much of the load bearing role, and accordingly dramatically reduce the physical requirement.
To people who have CADS, this is all terribly self-evident. To the uninitiated it is baffling. So here's a useful analogy: Picture yourself doing push-ups. It is hard. Now think of a bed spring between your sweater and the rug. It's easier, right? In skiing, fatigue arises because your legs are doing what your arms do in push ups. Your feet almost never come off the ground, just like your hands in push-ups. Your extensors are in play all the time, and they get tired. Then along come CADS, which work like a spring between the buttocks and the ski, like a bed spring in push ups. Bionics means gain without pain.
So what are the medical implications of all this? Profound relief for knees is one. Most people with arthritic knees are enabled to ski without symptoms. There is useful relief for foot, ankle, and hip problems. Many lower back problems are ameliorated, but not all. In conferring so much added strength and stamina, it is no longer necessary to have the strength to walk to have a satisfactory ski experience.
What are the safety issues? For starters, we think we are seeing a paucity of falls and injuries among CADS users that could be attributable to reduced fatigue. What should it mean to be able to ski without thigh burn and the resultant cumulative fatigue? After all, skiing is hard to prepare for with exercise. On a more specific note, some doctors and biomechanical engineers are beginning to postulate that CADS might bring about a reduction in forces at the anterior crucial ligament (ACL) in certain kinds of falls. Stay tuned for reports of research in this important area.
For the frequent skier or career skier, joints wear out with predictability that exceeds that of any other repetitive strain injury in the American workplace. (At least that's my impression. WD) Sometimes the process begins with a trauma and/or its corrective treatment. Sometimes there is a genetic predisposition. Any cursory survey of instructors or patrollers who have skied for a living for thirty years will reveal such a prevalence of degenerative joint disease as to suggest that its avoidance is possible only through a combination of great genes and great good fortune.
This prevalence is due to characteristics of skiing that CADS change. Skier's thighs burn because of the biomechanical inefficiency where gravitational and inertial forces meet leg design. At sixty degrees of flexure, twenty pounds of pull is required at the patellar tendon to create a pound of lift at the pelvis. In a one-hundred-and-sixty pound skier, this in turn results in pressure between the knee cap and femur of two thousand pounds. Hence, imperfect knees hurt. The weight bypass, joint unloading, and muscle augmentation of CADS alter the dynamics dramatically in favor of the skier. The immediate result of reduction or elimination of thigh burn and arthritic symptoms would seem legitimately suggestive of a long term benefit.
That is a brief overview. To research you own area of interest, click on any of the categories below. This will access relevant references from customer letters or published articles.
See the Vermont Adaptive Ski and Sport site for more about skiing with CADS