Need for Adaptive Downhill Skiing Equipment
The First Downhill Sit-Ski
Peter Axelson designed the first ski that people could use in a sitting position in 1978, while he was a product design and mechanical engineering student at Stanford University. He developed the Arroya sit-ski to its present configuration while a rehabilitation engineer at the Department of Veterans Affairs Rehabilitation Research and Development Center in Palo Alto, California.
The Arroya sit-ski features four inward-facing stainless steel edges that allow seated skiers to traverse, turn, and stop by shifting their center of gravity. A tunnel section between the runners reduces surface friction and increases traveling speed. Since 1979, people with disabilities have used the Arroya sit-ski in slalom, giant slalom and downhill competitions at the National Handicapped Ski Championships, sponsored by the National Handicapped Sports and Recreation Association.
Beneficial Designs manufactured the Arroya sit-ski from 1981 to 1985. Molds and tooling for the original Arroya sit-ski are still available to interested manufacturers. Other companies are now commercially manufacturing sit-skis similar to the Arroya.
People seeking adaptive skiing programs where they can use the Arroya sit-ski should contact:
Disabled Sports USA
451 Hungerford Drive, Suite 100
Rockville, MD 20850
This project was funded by the Department of Veterans Affairs Rehabilitation Research and Design Center and Beneficial Designs, Inc.
Need for an Adaptive Ski
Many people with mobility limitations enjoy participating in winter recreational activities. With adaptive ski equipment, wheelchair riders have the option to join their friends and family on the alpine ski slopes.
Innovative Design Features
Peter Axelson designed and built the first chairlift compatible mono-ski with shock absorbers. The Arroya mono-ski utilizes a four-bar linkage similar to the suspension on many motorcycles. A Fox motocross shock absorber with adjustable dampening controls connects the ski to the seating system and absorbs bumps at high speeds. The seating system consists of a custom molded orthosis with fiberglass rods that help the rider sit up after leaning forward. The seating system was designed with the help of Allen Siekman and others at Children\'s Hospital at the Stanford Rehabilitation Engineering Center.
A Winning Design
Peter Axelson has ridden his creation to a number of world class skiing competition victories, including the 1986 downhill gold medal at the World Championships for the Disabled in Salen, Sweden, and third place in the 1988 World Championships giant slalom at Innsbruck, Austria. At the 1990 World Championships in Winter Park, Colorado, Peter Axelson used his mono-ski to medal in all five events, winning two gold and three silver medals.
The Arroya mono-ski is not being manufactured by Beneficial Designs. The patented design was released into the public domain to encourage adaptive ski manufacturers to incorporate the unique design features into their own mono-skis. This has made the innovative technology widely available to adaptive skiers.
Those interested in purchasing a mono-ski should consider reading articles on adaptive sports equipment in magazines such as
This project was sponsored by Allen Siekman, Children's Hospital at Stanford, Volkl USA, the U.S. Disabled Ski Team, Fox Factory Inc., and Beneficial Designs, Inc.
Mono-Ski Training Simulator
Need for an Indoor Ski Training Machine
Equipment exists for standing skiers to practice skiing off the snow on a moveable platform allowing them to extend their feet in either direction. Skiers with mobility limitations who use sit-skis and mono-skis would benefit from a device allowing them to mount their equipment and train indoors.
Skier's Edge Modifications
Students at Montana State University worked with Beneficial Designs to develop a prototype modification on a Skier\'s Edge machine. A long bar with a T knee rest and padded foot support were mounted on the movable shuttle where stand-up skiers place their feet. A molded plastic bucket seat placed over the shuttle allows skiers to shift their weight from side to side to simulate turning. Flexible outriggers with handles anchored at the left and right feet of the device act as poles and provide the skier with upper body support. An additional leg for the base that stretches forward from the center out past the leg bar on the shuttle stabilizes the device against the skier\'s side-to-side rocking movements.
Skier's Edge provided a commercial training unit for modification. This project was funded by Beneficial Designs, Inc.
Dynamic Cross-Country Ski
Need for a Dynamic Adaptive Cross-Country Ski
Nordic ski equipment for people with mobility limitations consists of a seating support and frame chassis mounted on cross-country skis. Fixed at standard cross-country track width, the skis join the frame with industrial shock mounts. The shocks allow the skis to flex beneath the skier for a smooth ride but cannot store the energy of a push to be released at a later time. Adding a suspension capable of transmitting a dynamic kick would permit users to maintain their forward momentum between each pole stroke.
The dynamic cross-country ski has gone through numerous iterations beginning with a version built on wheels used for training on land that allowed the skier to tilt fore and aft for increased range of motion. Springs pull the skier into a rear-tilted position. When reaching forward with poles, the skier tilts into a forward position, stretching the springs. As the skier poles through, the springs snap the skier back into a rear-tilted position producing a kick-and-glide effect.
The prototype has been implemented in a version that can be used on the snow. The device has practical application for speed and racing efficiency for cross-country skiers with lower extremity impairments.
This project is sponsored by Beneficial Designs, Inc.