This study assesses the use of electromyography (EMG) in ergonomic improvements. The use of auxiliary handling devices in the construction industry, a change in a tool and a work method used in upholstered furniture manufacturing, a change in work methods in work with a computer mouse, and a change in a piece of furniture in work with a microscope are examined. The results indicate that ergonomic solutions can be found for common musculoskeletal risk factors, and the effect can be confirmed with EMG amplitude analysis. The repeated-measures design and normalizing EMG with the individual mean amplitude should be used to evaluate the improvement effect. Using the amplitude probability distribution and normalization using the electric activity during a maximum voluntary contraction helps to evaluate the practical meaning of the changes.