Can the strength of back muscles actually be measured?

Yes, but no exact values are considered “normal” by age, weight, gender, or range of motion. Instead, a range of values is used, given as ratios.

Some research has provided strength ratios for men compared to women. Researchers using a computer-based device called a dynamometer show that women can exert about 50 percent of their body weight. This force is about 65 to 75 percent in men. All the people in the study had a history of back pain.

More studies of maximum strength are needed both on “normals” (people without back problems) and those with a history of chronic back pain.