Effects of manipulative therapy on longissimus dorsi

It is important to keep the horses back and its muscles healthy in order to secure normal function and ability to carry a rider. Longissimus dorsi is one of the muscles in the back, bilaterally contracted it contributes to extension and unilaterally lateralflexion of the back. In this study two different treatments were executed on this muscle. In both cases significant differences were found in muscle tone and electromyographic (EMG) activity immediately after the treatments.

A group of general riding horses were used for the study. The group was split into three subgroups; one group received McTimoney spinal manipulation, one received reflex inhibition treatment and one control group. The resting tone and EMG activity while walking an eight shaped course were measured before and after treatment.

Both groups which had received treatment showed immediate decrease in tone and EMG activity, the control group did not show any changes. However, tone and muscle activity were only measured straight after treatment, these measurements may not reflect the condition of the muscles hours or days posttreatment.

It is not known whether the decreases measured are due to less pain or an increase in performance, as well as if they are clinically appropriate. Another interesting result was the five times greater EMG activity of the Longissimus dorsi during an inside turn than for straight walking and an outside turn. This result highlights the importance of the Longissimus dorsi in providing lateral flexion for turns in walk.

> J. Wakeling et al., Equine and Comparative Exercise Physiology 3 (2006) 153–160. All rightst reserved to: Cambridge University.  Click here for the fulltext