Pick This Up: How to Lift without Losing Your Balance
Bend your knees when lifting! Most people have heard this advice by now. But how much bend is enough? Is it better to do a full squat or a semi-squat? Is it better to put more stress on your back or your knees?

Lifting injuries to the low back are common in the workplace. These can happen from lifting unexpected loads, slipping during lifting, or even falling while lifting objects. Recently, researchers have looked at how lifting an unexpectedly heavy load affects balance.

Two groups of healthy male volunteers were recruited to compare lifting techniques. One group used a deep squat with a straight back to lift objects. The other group used a semi-squat and leaned forward (stooped) when necessary. When the load was heavier than expected, the group using the full squat and erect posture was more likely to lose balance and fall forward.

Losing balance usually means dropping or returning the load to the ground. On a second attempt to lift the same object, jerking motions are used that can increase the risk of back injury. Researchers also showed that the muscles' reaction to an unexpected weight is important. This is true on the first attempt to lift and on the second try. Whenever possible, using smooth muscle movements (instead of jerky motions) reduces the risk of injury.

Lifting technique does make a difference, especially when lifting an unexpectedly heavy load. Using a deeper knee bend and keeping the back straight may cause a loss of balance. This risk is reduced in these instances by using a semi-squat and slightly stooped posture.
References
Deborah G. Heiss, PT, PhD, OCS, et al. Balance Loss When Lifting a Heavier-Than-Expected Load: Effects of Lifting Technique. In Archives of Physical Medicine and Rehabilitation. January 2002. Vol. 83. No. 1. Pp. 48-59.