The participants from all three groups performed shoulder abductions before the 10-week intervention began and after it ended. During this pre- and post-test, the participants were required to contract the muscles as fast and hard as they could. The researchers measured the force and speed of the lift. In particular, they wanted to measure rapid force capacity, that is, how quickly the women could activate their muscles to generate force.

They also obtained muscle biopsy samples to analyze how the training affected the muscle fibers and pain levels at each of the sessions. The pain data was compared to performance.

Results

In this study, bicycling did not significantly affect rapid force capacity. The significant changes on this variable occurred only in the strength-training group. Strength training reduced pain levels by more than 50%, and also:

improved rapid force capacity increased number of type II muscle fibers, the fibers important in generating power

The authors speculate that strength training reduced the pain, which then enhanced the body's ability to rapidly activate the muscle. Activating the muscle depends upon rapid coordination of nerve signals and it was the nerve signaling that seemed to have improved. The researchers also said that the strength training may have encouraged the women to set aside the fear of pain and thus helped improve performance.

In addition to providing further evidence that these five exercises can help women who suffer trapezius myalgia, the study also showed that reduced rapid force capacity can be a good screening tool to determine who would benefit from this type of rehabilitation, the authors said.

Source: American Physiological Society