Marine propulsion – Oar or paddle
Reexamination Certificate
2001-02-21
2003-03-25
Basinger, Sherman (Department: 3617)
Marine propulsion
Oar or paddle
C416S07000R
Reexamination Certificate
active
06537117
ABSTRACT:
1. FIELD OF THE INVENTION
The present invention relates to the ergonomic grips. More specifically the present invention relates to ergonomic grips for use in sporting equipment.
2. TECHNICAL BACKGROUND
Kayaking is a growing sport in the United States and throughout the world. There are a number of different types of kayaking and the boats and paddles associated therewith are designed for the particular type of activity engaged in. Thus, there are both calm water kayaks and white water kayaks along with sea or ocean kayak. For centuries, Eskimos have paddled Arctic waterways to hunt and fish in kayaks, a type of canoe built from skins stretched over a frame. Today's high-tech versions of the kayak, made from plastic, Kevlar and fiberglass, are still decked with a cockpit for the rider, who propels the boat with a double-bladed paddle.
The sport of kayaking is growing rapidly in popularity. It is believed to be second only to snowboarding in growth. Driving that growth is a recent revolution in kayak hull design that has made doing tricks, such as wave surfing, squirts and spins, much easier. There are an estimated 1.3 million white water kayakers in the United States, 400,000 of whom can be considered “enthusiasts.” One of the reasons for the increasing popularity of the sport it that a kayaker can experience solitude and wilderness on the one hand and excitement on the other.
Recent developments in kayaks have fueled the increased interest in the sport. In some instances, kayak builders have followed innovations in surfboards to come up with boats that “plane,” riding on top of the water instead of in the water.
As kayaks have improved and developed, additional sports and activities are possible. Where traditional kayakers simply traveled a waterway, modem kayakers maneuver and perform tricks to improve and demonstrate their skills. To promote these types of activities, kayak rodeos are springing up around the country. Many of today's kayaks are specifically designed to be used in rodeos. These boats are generally small and sharply angled. These boats, however, are not ideally suited for river running in that they are too slow and do not track well. Thus, “park and play” is a growing phenomenon, while down-river running is declining in popularity. This marks a radical departure from the roots of these sports, which were born from the need to get from one place to another. Thus, innovation is allowing more people to get into kayaking and to do different things on a river.
As kayak's have evolved allowing the sport to evolve, there is also a need for improvements in paddle design. Generally, a kayak paddle is comprised of an aluminum or wood shaft. The shaft is generally approximately 1.25 inches in diameter. This diameter allows the user to directly grip the paddle. There are generally no specific grips or other structures to allow the user to securely hold the paddle. At times, the user may modify his own paddles by adding tape or other wrappings to make the paddle more comfortable and usable.
Generally, however, the development and improvement of the paddle has not kept pace with development in the kayaks themselves. In particular, kayak paddles have not been designed to address the injury that can be associated with kayaking. New designs in paddles have tried to address the risk of injury to the shoulder, elbow, and wrist. Many manufacturers state that their product is “ergonomically designed,” but provide little information on how the products are ergonomic. Ergonomics come from the Greek words “ergos,” meaning work, and “nomos,” meaning knowledge. Ergonomics involves adapting a tool or other object to the needs of the worker or user, rather than trying to make the worker adjust to the tool. However, little information is available about how to design an ergonomically correct grip, especially a paddle grip.
A major motivation for ergonomic design is the improved performance and health of the user of the tool. In the field of kayaking, fatigued or uncomfortable kayakers are less capable of maintaining safe performance of their task. If they are required to perform repeatedly and beyond their physical capabilities, breakdown and injury will recur. The resulting injury is what is commonly classified as a cumulative trauma disorder. Injuries that occur with poor ergonomic design are usually disorders of wear and tear, including overuse syndromes, repetitive strain injuries, musculoskeletal injuries, and compressive neuropathies. Injuries common to kayaking include carpal tunnel syndrome, wrist tendinitis, medial or lateral elbow epicondylitis, and rotator cuff muscle strains and tears. Cumulative nature of these injuries indicates the injury occurs over a period of weeks, months, or even years, or as the result of repeated stresses on a particular musculoskeletal area. Each repetition of an activity can produce a small trauma to the tissues and joints of the body.
Although the human body has enormous self-repair abilities, continued exposure to stress can outweigh these abilities, which then results in injury. Factors such as force strength, high repetition, awkward posture, reduced recovery time, and environmental factors like vibration and cold exposure can lead to injury over time. All of these factors can produce injury alone, but the incident of injury is increased when these risk factors are combined. The simple activities of repetitive gripping, twisting, reaching, and moving can be hazardous when repeated numerous times over an extended period.
Static overloading results from muscles being subjected to too much stress over a period of time. The small muscles of the hand and the extensor muscles of the wrist are most vulnerable to static overloading. These muscles stabilize the hand during forceful use and balance the extensor tendons during fine manipulation. Sustained contraction can result in tendinitis, especially about the elbows. Spreading the load over as many muscle groups as possible will help to avoid overloading the smaller muscle groups. In the case of kayaking, inappropriate paddle design can increase the risk of injury to the hand, arms, shoulders, and back. Because kayaking involves repetitive use of a hand tool, namely the kayak paddle, a kayak paddle can be designed according to ergonomic standards.
Poor paddle design can overstress the muscles, resulting in fatigue and unnecessary dissipation of energy for paddle retention. When a paddle does not properly fit in a user's hand or becomes wet and slippery, a user may exert a large force to grip the paddle. Such power gripping requires force greater than 50 pounds per hand and can be detrimental. If the wrist is also used to exert the force, a grip force of 32 pounds is acceptable. Because of their lack of bony and muscular protection, the neurovascular bundles of the fingers are very susceptible to contact stresses. Handles that are profiled for the fingers and lack of protective cushioning make these areas susceptible to trauma.
Another consideration in designing an ergonomic tool such as a kayak paddle is maintaining adequate blood flow in the muscles. During muscular contraction, blood flow can be impeded to levels as low as 40% of the maximal voluntary contraction for the muscle. Static muscle contractions reduce the blood flow as long as the contraction is maintained. Metabolites accumulate and oxygen to the muscle can be quickly depleted, resulting in fatigue. Muscle fatigue, defined as a decreased force generating capacity, develops gradually during exercise and is distinct from exhaustion, which occurs when the hard force or exercise intensity can no longer be maintained.
The position of the forearm and wrist during paddling are also important. It is well known that when the wrist deviates from the neutral the strength of a user's grip is reduced thereby requiring the user to exert a greater force to hold the handle. Different postures appear to result in compressive and shearing forces on the tendons, which may be transferred to adjacent nerves. The eventual consequence
Gunnell Lance F.
Larson Brad J.
Basinger Sherman
Madson & Metcalf
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