By Bob Niklewicz PT 

Last week I introduced you to the Class 1 Lever. It is the primary lever used in pruning and prying up large stones or the toughest of weeds. I presented the key elements to successfully overcome stubborn weeds or thick branches. Those elements are: Applied Force, the Fulcrum and Resistance. Force is what the gardener generates physically when they use pruners/scissors or a pry bar.

Leverage can also help you protect your back and legs when the amount of resistance becomes even greater or the quantity of materials is larger than can be safely handled.

Image 1

For instance, how do you safely carry or move a heavy load like a sack of potatoes or gardening material such as rocks, branches or soil as seen in Figure 1?

In those cases a “Class 2” Lever is what you need. A “Class 2” used in the garden is most commonly found in a wheelbarrow. Image 2. You could carry the weight the old fashion way like the men grunting in Image 1. Or save your back, legs and several trips by using a Wheelbarrow Image 2. A wheelbarrow is a Class 2 lever set up. The weight is placed between you and the Fulcrum.

Image 4

The Long handles move the load safely towards onto the wheel that is the Fulcrum as shown in Image 3. However, the mechanical advantage is negated by a poor lifting posture as seen in Image 3. There he is bent forwards, knees are straight and the strain of lifting will be placed at the discs and muscles of the low back. In Image 4  the model has perfect lifting posture by keeping his back straight, and his head up. He can lift the load safer by using his leg muscles as the weight is transferred to the wheel. A balanced, stable posture makes the load safer to lift and move.

Diagram 5

Then there is also the “Class 3” Lever. The Class 3 is the most common lever in the body.  It is designed for speed as the Force is generated close to the Fulcrum. Diagram 5 “F”. The Class 3 takes less motion at the Fulcrum to generate a larger and faster arc of motion. This set up allows us to shovel, climb or throw rocks with more velocity. Images 6 & 7 show examples of the Class 3 as used during shoveling.             

In Image 6  the load (resistance) is at the end of the lever (wrist, holding shovel) and the effort (your lower hand) and the fulcrum at the top hand. When the effort (your lower hand) is further up from the shovel blade, you will stand straighter but will have less power to lift. In Image 7 the hand is even closer to the blade. You will have more control and power, but you take the chance to strain your low back. In Image 8 The person can stand much straighter, move faster but has less power. A trade off to protect your back.

Image 8

Using tools that take advantage of leverage will reduce your chance for injury. If you rotate tasks or change hands/sides when using tools while gardening, it will make the job easier and safer to do. It does take a little awareness and practice to frequently change sides or postures but you will be safer at the end of the day.

Bottomline: Use tools that allow you to “leverage” a task without hurting your body. 

Napa Master Gardeners are available to answer garden questions by email: mastergardeners@countyofnapa.org. or phone at 707-253-4143.  Volunteers will get back to you after they research answers to your questions.

Visit our website: napamg.ucanr.edu to find answers to all of your horticultural questions.

Photo credits:

Image 1, ABC News; Image 2, Dreamstime; Wheelbarrow and shovel photos by Olga Morham; Diagram 5, (elbow joint), CC-BY-SA; Image 8, Dreamstime

Information links:

UHSBerkeley.edu-ergonomics tips for gardening at home

https://uhs.berkeley.edu/sites/default/files/ergonomics_tips_for_gardening_at_home.pdf