Garden Ergonomics
Why is this important?
Gardening activities contain many of the risk factors associated with Cumulative Trauma Disorders, or "CTDs". CTDs are a variety of disorders such as carpal tunnel syndrome and tendonitis that develop over time as a result of repeated "micro-traumas" to the soft tissues of the body. Certain movements can cause tendon irritation, obstruction of blood flow through arteries, or compression of nerves. These brief, individual incidents may not cause any noticeable impairment on their own, but their repeated and combined affect could cause or aggravate a larger problem.
What should I do to avoid Cumulative Trauma Disorders?
The development of CTDs is dependent on many factors. But using tools that are designed with ergonomic principles can go a long way toward reducing the likelihood of injury.
Fiskars prides itself on being in the forefront of ergonomic tool design. The famous orange handled Fiskars scissors were designed in the 1960's to be the most comfortable scissors you could buy, even before the science of ergonomics was in wide spread practice. Since that time, many Fiskars lawn and garden tools have been designed to reduce the fatigue and effort of everyday gardening activities.
What are the primary CTD risk factors?
• Repetitiveness: Many lawn and garden chores are repetitive by nature. Trimming hedges, pruning bushes, or planting bulbs often require the same muscles to be used over and over again.
• Postures: "Postures" refers not only to your whole body position, but also to such things as the angle of your wrist while using a hand pruner. Grip strength is at its maximum when the wrist is in a relaxed or neutral position. Testing has shown that people lose up to 25% of their grip strength when their wrist is bent. The bent posture shown here, called an ulnar deviation, is the most potentially dangerous. The tendons responsible for flexing the fingers are easily irritated by exertions made while in this posture. Many pruning activities also require bending and stooping which are hard on the knees and back.
• Contact stresses: Many tools are made with finger grips molded into the handle, to provide better slip resistance. However, these "form-fitting" grooves only fit one size hand perfectly. People with larger hands will find that their fingers overlap the ridges, causing pain, soreness, and calluses. Those with smaller hands will have to spread their fingers to match the grooves. Strength testing has shown that this spreading of the fingers significantly reduces grip strength, requiring more pressure to maintain control of the tool.
• Forceful exertions: Pruning activities require the application of force by the hands and/or arms on the tools that do the cutting. Depending on the material being cut, the design of the blades, and many other factors, the force required may be high or low.
What are some additional contributing factors? • Gender: In general, adult females are about 2/3 as strong as adult males. However, studies have shown that women have only about 1/2 of the grip strength of men.
• Age: Strength peaks somewhere between age 25-35. People lose approximately 10% of their strength by age 40. By age 50 they lose 15%. By age 60 they lose 20%. By age 65 they lose 25%. And by age 75, strength loss will be around 40%.
• Gloves: Many lawn care chores require the use of garden gloves to protect against the thorns and burrs of the branches being pruned. However, this protection comes at a price. Gloves that are too loose or too thick affect the user's grasp, causing the fingers to spread too far apart. Testing has shown that cotton garden gloves reduce grip strength by an average of 26%, compared to bare-handed strength.