Freshly fallen snow always seems so beautiful, peaceful, serene, until you have to go somewhere. At a quarter of eight on a Monday morning, faced with the daunting task of getting a two wheel drive car out of a not-so-toasty garage and down a snow-clogged driveway that seems to have grown by two or three football fields overnight, snow is never pretty.
Sure there are answers. Snowblowers, some kid around the block looking to make a couple of bucks before school, a nice neighbor with a snow-plow, heated driveways, the bus, telecommuting, a winter home in Florida, but for the average Joe, winter mornings mean a workout with the snow shovel, and possibly a pain in the back for the rest of the day.
While no one with an aching back, arms, shoulders or neck would doubt the validity of snow shoveling as an inherently unhealthy activity, the physical pain just doesn’t get the press that the cardio side of shoveling receives. But press coverage or not, back problems are there.
Residents in Rochester, New York throw around about 90 inches of snow annually, a little more than they see in Buffalo; out west, Salt Lake City sees 65 inches (although some Ergoweb employees argue that they receive closer to 100 inches at their nearby mountain dwellings), while those lucky cusses in Denver get not quite 60. The ergonomics problems arise when the residents in these cities, and others, feel the need to defy nature and leave their houses, shovels in hand.
Research has estimated that snow shoveling is the energy-expending equivalent of running nine miles in an hour; three hours later, and that’s more than a marathon, but without the benefits of training. But shoveling is also an asymmetric activity — the postures and forces involved in the task are not evenly distributed on or in the body. Shoveling involves twisting, which increases risks to the low back in particular. When shoveling, the load is often far to the front or side of the body, at the end of the shovel, which significantly increases the forces on the spine.
From an ergonomics perspective, shoveling has been studied since early in the last century. Frederick W. Taylor, working with Bethlehem Steel, tackled worker production in a shoveling task by matching the shovel to the type of material being moved. And, in some respect, today’s snow shovels might have Taylor to thank for their varying designs. Straight handles, long handles, short handles, bent handles. Some are scoops, some are plows. Plastic, metal, flat, curved, deep, shallow. Each is intended to do the same thing — make the daunting task of moving snow less painful.
A study published in November, 2001 by Liberty Mutual Research Center for Safety and Health looked at ten male volunteers, each fitted with a lumbar motion monitor to track the subject’s trunk position while shoveling with two different types of snow shovels — a bent shaft and a straight shaft, each fitted with a force/ moment transducer.
The researchers took an interesting approach — telling the volunteers to imagine they were being paid for their shoveling, but not to approach the task as a contest. Each was to clear the snow from the asphalt surface as quickly as possible but without straining or becoming unusually tired or out of breath. Breaks were granted as necessary. Subjects also were instructed to lift and throw the snow, not push it.
Bent-shaft shovels usually carry some sort of ergonomic label. And in the study, they proved to be more agreeable to the backs of the subjects, causing the men to bend forward 16 percent less than with the straight shaft shovel and reducing the force exerted on the lower back by up to 13 percent. Heart rates, also monitored during the test, were lower with the bent-shaft shovel. And six of the ten subjects said they preferred the bent-shaft shovel.
In a 1997 report by Cornell University’s Brad Coffner (Ergonomic Design of the Snow Shovel, 1997) on the ergonomics of snow shovels, Coffner stated that shovels with longer shafts decrease an operator’s trunk flexion and the forces at the spine, but “the lateral moment loading the trunk is, however, increased and the maximum force at the right erector spinae muscle is also increased,” wrote Coffner. Bent handle shovels were shown by Coffner to decrease the maximum spine compression and shear forces when lifting. And finally, an instance where it pays to be short — Coffner also showed that tall, heavy shovel operators had heavier loads on their spines and back muscles when shoveling compared to short, light shovel operators. Although, if that means the short folks get stuck weilding the shovel, maybe being tall actually has the advantage.
This article originally appeared in The Ergonomics Report™ on 2002-11-01.