In humans, the muscles that stabilize the spine—including the multifidi muscle—play an important role in maintaining health and function. Even small variations in muscle symmetry can result in potentially debilitating conditions such as scoliosis, said Sheila Schils, MS, PhD. Likewise, muscle asymmetry and associated back pain in horses can lead to poor performance.
People can perform exercises to strengthen and build a weak multifidi muscle, as can horses. But neuromuscular stimulation could be more effective for targeting precisely the muscles that need to develop in horses, said Schils, who presented on the topic at the 2017 American Association of Equine Practitioners Convention, held Nov. 17-21 in San Antonio, Texas. Functional electric stimulation (FES) is a type of electrotherapy that stimulates the motor nerves responsible for muscle function, meaning it could help achieve or maintain multifidi muscle symmetry.
Schils presented the results of a study in which researchers evaluated the therapy’s impact on equine multifidi muscle asymmetry. She is the principal of EquiNew, which produces FES equipment and provided it for use in the study and funded the statistical analyses. Diane Isbell, DVM, a private practitioner from Livermore, California; Suzan Oakley, DVM, Dipl. ACVSMR, of Oakley Equine Sports Medicine, in De Leon Springs, Florida; and muscle expert Ugo Carraro, MD, of the University of Padova, in Italy, carried out the study and statistical analyses.
The researchers tested FES on 12 horses of varying breeds and disciplines. Two had been retired due to back problems, while the remaining 10 were retired for reasons unrelated to the back. Twelve other horses that had not been diagnosed with back problems served as untreated controls. None of the 24 horses had been ridden for at least two months prior to the study. They were turned out in a paddock for one to six hours daily and stalled at night.
During the study the researchers treated the 12 retired horses with FES for 35 minutes three times weekly for eight weeks. The researchers placed a back pad with six electrodes between thoracic vertebrae 10 and lumbar vertebra 4, which produced symmetrical longitudinal (from front to back) pelvic rotation for two seconds, said Schils, followed by a two-second pause before stimulating again.
She said the team used the Modified Ashworth Scale (MAS) to determine the horses’ muscle tone level before and after FES treatments; Grade 0 represents healthy muscle tone, while Grade 4 represents a “hypertonal” muscle that is rigid in extension or flexion. To determine changes in the size of the multifidi, they used ultrasound to measure the cross-sectional area (CSA) of the multifidi at seven locations before and after the eight weeks of treatments.
Key findings included:
Key findings included:
- – Most horses were Grade 3 on the MAS, with two classified as Grade 2; Schils said the horses included in this study were almost twice as hypertonal as the average horse she sees—a factor she believes could be due to lack of exercise. “Correct exercise is so important to keep the muscles properly toned, especially with increasing age … we certainly notice that in ourselves, too”;
- – It took an average of 9.8 treatments to obtain a one-grade MAS improvement;
- – After eight weeks of treatment, ultrasound of the multifidi muscles showed a significant improvement in symmetry at all locations; and
- – There was no change in the size of the multifidi after eight weeks in the horses receiving no FES treatments.
Schils said these results suggest FES might help reduce back pain in horses with asymmetric multifidi muscles. However, she noted FES won’t replicate the same level of motor control necessary for sport performance.
“FES will get the muscles activated and symmetrical, but then you must transfer that improvement in muscle function to the work under saddle, so the horse can perform their job in better balance,” she said.
Source: https://thehorse.com
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