Both groups did a specific exercise program every day for seven weeks. Everyone was tested again at the end of that time. The results showed that everyone increased in trunk extension strength. However, trunk extension strength wasn't linked with LBP.
The researchers were surprised to find that handedness was a key factor. Right-handed players with LBP had lower electrical activity in the muscles on the left side of the spine. The same was true for left-handed players (reduced strength on the right side). These changes were still present even after the exercise program.
Other studies have shown that muscle recruitment patterns are changed by training or handedness. With tennis players, one-sided motions may lead to asymmetric (uneven) patterns of muscle activity.
As a result, muscular imbalances occur, which may or may not be linked with LBP. Further study is needed to find out if neuromuscular imbalance is the cause or result of LBP. It's likely that a specific exercise program to retrain muscular imbalance is possible. Whether or not it will reduce back pain or other injuries is unknown.