There are two types of manual lifting: either using your body or using manual lifting machines, like a crowbar or a hoist. We all use both methods around the house.
Our bodies are complex biomechanical machines made of about 40% muscle, with many levers and joints. Think of yourself as a small construction excavator.
My neighbour is an excavation contractor, and he owns many excavators from huge ones to a tiny one that could fit in your basement. For industrial lifting, each machine is rated with the amount that it can safely lift, called a working load limit. My neighbour will select the correct excavator capacity for the job requirements.
When doing manual lifting at home, we need to consider the same thing, by matching the job requirements to our physical capability. In industry, this is known as occupational ergonomics.
Every person has their own working load limit. My brother, Kevin, found his working load limit a couple of months ago when he was lifting firewood. He is 50 years old and in reasonably good shape, but he went over his limit and ended up with a double hernia. He had surgery a couple of weeks ago and is recovering nicely.
Whether you use an excavator or use your body, there are several things to consider before lifting.
- Are you in good physical condition? Are you healthy? Do you exercise often? Are you stretched and warmed-up? An old excavator cannot lift as much as a brand new one.
- How heavy is the lift? Maybe your machine is not big enough.
- How far do you need to reach? Can you keep it close to your body or do you have to reach out 60 cm for it? Keeping the load close to you reduces the strain on your back. Keeping your back straight, and bending your knees to lift, reduces the force on your back.
- The same consideration applies for using your arms. The further the load is from your body, the greater the force needed to lift it.
- Do you have to twist while lifting? This is a bad. The correct method of manual lifting is to face the object, lift it, and turn your feet, not your back. Also, using both hands to lift a load is much less physically demanding than using one hand and arm, and it keeps your back in the correct position. When lifting, remember the expression “keep your nose between your toes,” which will help to prevent you from twisting your back.
- How many lifts do you need to do? Are you lifting one brick, or 1,000? The more repetitions you do, the more chance for injury. (As many of us have experienced shovelling snow). An excavator that works all day long will wear out quickly.
- Is the position a wide stance or an awkward position? Compare lifting a big Ikea box with moving a similarly weighted two-four of beer.
- Can you break down the load into smaller ones? I hope my brother cuts his firewood into smaller chunks from now on.
A construction excavator has a certain range of travel where it can apply its maximum force. Our bodies work the same way; we call this range of movement “the power zone.” It’s the most efficient and safest area for your arms and back to perform lifting. It is close to the body, at your navel, between mid-thigh and mid-chest height. The amount of force required (and the risk of injury) increases when you work above or below that zone.
I once had a tour of a shipyard and the manager said that they try to design the ships to allow all welding to be done in the downward direction (the power zone) because it is easier on the workers, they are more productive, and it improves the quality of the welding.
Whenever I think of the power zone, I also think of poor Michelangelo, who spent four years standing on a scaffold, reaching up with his brush, to paint the ceiling of the Sistine Chapel in Rome. He wrote about how the process wore him out. Today we would call that a repetitive strain injury.
I have been involved in lifting in all sorts of ways, with manual machines and cranes, for a large part of my career. One of the more interesting crane lifts was recovering a railway locomotive from under a lake in Quebec. In all these jobs, we used two cranes. When doing manual lifting around the home, ask for help if someone else is available and capable. On the job we call this “team lifting.”
And when possible, use a tool to make the job easier.
- Jacks are amazing tools. I’ve lifted a house with one. My dad taught me to change a tire when I was about 12 years old. (Hint from my dad: if you want to keep your hands, always put them on the sides of the tire, when changing one, never on the top and bottom).
- On several occasions, I moved a 700-kg machine without wheels, on a concrete floor on my own, using only a crowbar and a block of wood. By putting the block of wood on the floor and biting into it with the bar, you can move the object with leverage. This method also works to move the object up a ramp.
- Consider using a ramp to slide a heavy object to a higher or lower level instead of lifting it. Put the object on a thick plastic bag, like a salt bag, to reduce friction. Google “how to build a wooden ramp” for more details.
- Lift in stages. Instead of one big lift, move the load from the floor to a mid-level, using a wooden box, etc. Then move yourself to a mid-level and complete the lift. People often instinctively do this when moving something like a heavy suitcase upstairs.
- Winches and hoists can be an article on their own. They’re handy, but bring other dangers. If you intend to use them, do your homework.
As you see, lifting is serious business.
Meanwhile, this article is an incentive for me to get off the couch and start using my weights more, so that I can become a more powerful lifting machine.