A Static Bioimpedance and Dynamic Acoustic Myography Preliminary Assessment of Low Frequency Therapeutic Ultrasound Treatment of the Shoulder Muscle Trapezius: An Equine Study

Background: In horses, therapeutic ultrasound has been shown to be beneficial for suspensory ligament injuries, and more generally to stimulate tissue repair and reduce localized pain. However, it has yet to be examined in relation to soft tissue injuries sustained during competition or in connection with rider/saddle interactions. Aim: The aim of the present study was to examine the efficacy of topical low-frequency therapeutic ultrasound on the shoulder muscles of injured horses. Methods: Muscle mass and cellular health was assessed for M. trapezius using non-invasive multi-frequency bioimpedance, and dynamic improvements in M. trapezius and M. latissimus dorsi were examined using acoustic myography (AMG). A total of 8 injured horses (painful to palpation and atrophied) were treated using an EQ Pro Therapy unit, following a set protocol that comprised treatment every other day for 10 treatments. Pre-treatment values were then compared with post-treatment measurements (1 & 6 months later). Results: The mfBIA results for M. trapezius showed a significant improvement (P < 0.05) of EQ Pro Therapy treatment for the membrane capacitance (Mc) and phase angle (PA) parameters when comparing the Pre vs Post 1 and Post 1 vs Post 2 measurements. Similar improvements were seen for the AMG measurements for M. trapezius and M. latissimus dorsi where statistically significant improvements in the muscle efficiency (E-score) and temporal summation (T-score) as well as the spatial summation (S-score) and mean of the ST-scores were noted (P < 0.05 to P < 0.01). Conclusion: The present findings suggest that EQ Pro Therapy treatment is efficacious in terms of equine cases involving soft tissue shoulder muscle injuries (painful to palpation and atrophied). The main improvements noted were not only increased muscle mass and cellular health but also improved force production, better coordination, and lateral balance, which persisted for at least six months after treatment.

Acoustic Myography: Its Assessment of Ground Reaction Forces as Measured through Forelimb and Hind Limb of the Horse during Mild Exercise

Background: Fractures in the limbs of racehorses are common, resulting among other factors, as the result of repeated ground reaction forces on bones and joints, leading to catastrophic failure. Aim: To quantify ground impact transmission through the limb bones of un-shod healthy horses using the non-invasive technique of acoustic myography (AMG). Methods: Four sites were selected for AMG measurements at the walk and trot, hoof wall (site 1) and sites 2 - 4, metacarpal 3, carpals and the radius of the left forelimb of two healthy horses. Measurements were on both rubber and concrete. AMG of the equine hind limb suspensory system was made and analyzed (amplitude and timing) for the proximal suspensory ligament (PSL) and the SDFT/DDFT. Results: AMG signal amplitude at site 1 (1.5 ± 0.2 versus 1.1 ± 1.5) was not found to be significantly different at the trot compared to the walk;however, sites 2, 3 and 4 were all significantly different when compared between the two gaits;site 2 P = 0.008;site 3 P = 0.006;site 4 P = 0.005. AMG signals recorded on the rubber surface had smaller amplitude than the equivalent signal and site on the concrete surface. Ground Reaction Force (GRF) transmission in the equine forelimb was 22 m/sec, whilst that of the hind limb suspensory system was 25 m/sec. Conclusion: Findings indicate that GRFs are transmitted proximally along the limb at considerable speeds, that they are dampened by tissues and structures in the limb, and that the GRFs are present and detectable proximal to the fetlock joint.

Acoustic Myography in Assessment of Isokinetic and Isometric Muscle Strength in a Healthy Danish Population

Isokinetic and isometric force measurements involving a dynamometer setup are widely used in training and in muscle assessment. For further understanding of the method, we investigated the activation of key functional muscles during isokinetic and isometric movements. During force measurements in an isokinetic Biodex System 3 ProTM, acoustic myography (AMG) was applied. Ten healthy subjects (5 men/5 women) in each decade from 20 to 69 years of age participated in the study. Measurements were carried out during extension and flexion of the ankle, knee and elbow joints. Muscle fibre use was measured by efficiency (E-score) and fibre recruitment (temporal (T-score) and spatial (S-score) summation). AMG measurements showed good reproducibility, and the recruitment pattern of muscle fibres did not change with gender or age. Overall, a significantly higher E-score (P < 0.05) was found at the lower angular velocities than at the higher ones, indicating a lower level of muscle efficiency at higher velocities. Muscles used for knee movement exhibited higher scores than muscles associated with the ankle and elbow joints, most likely related to the greater degree of force production at this joint compared to the ankle and elbow. The ability to activate and inactivate muscle fibres during periods of isokinetic activity becomes increasingly more difficult as the velocity increases. When assessing training effects in sports or rehabilitation, AMG in parallel with isokinetic measurements adds important additional information by giving a measure of possible improvements in efficiency and fibre use.

The Effects of Using a Specially Designed Stirrup on Kinetic Energy Absorption by the Knee Joint of 12 Show Jumping/Eventing Riders

The use of Winderen Knee Protection Solution stirrups compared to standard iron stirrups, reveals the following benefits: 1) A reduction of stress or strain time in the order of 14 seconds per minute of activity whilst walking and 5 - 7 seconds less whilst trotting or cantering for muscles around the knee. 2) A reduction of stress or strain time in the order of 25 seconds per minute of activity whilst walking and 9 - 10 seconds less whilst trotting or cantering for ligaments around the knee. 3) A significant improvement in the E-score (less time exposed to stress and shock) and ST-score (lower force around the knee) whilst walking. 4) A considerable improvement in rider comfort and feeling of leg stability (self-assessment) compared with the owners current stirrups, whilst riding.

Anon-Invasive Assessment of Ground Reaction Forces in the Human Leg in Response to Walking, Jogging, Running and Jumping

Running is one of the most popular forms of exercise. Even though regular exercise is beneficial to human health, running is also often associated with an increased risk of injury. Lack of shock absorption in running shoes has often been stated as one of the main reasons for why running-related injuries have been on the increase. The aim of the present study was to assess the degree to which ground reaction forces (GRF) can be dissipated in the human leg in a barefoot subject, in connection with diverse physical activities. Acoustic myography (AMG), a non-invasive technique that records pressure waves from contracting muscles as well as the harmonic damping of ligaments, was applied to four anatomical sites on the subject’s leg, during barefoot walking, jogging, running and jumping. The data for walking on a hard surface show much lower ESTiTM parameters than those for the soft surface, and these lower values are observed mainly for sites 1 (toes;65%) and 2 (ankle;53%), respectively. AMG parameters for jogging reveal this gait to have very low ESTiTM parameters for site 1 and site 2 (ESTi 2 - 3), yet similar for both surfaces. The data for running on a hard and soft surface revealed much lower ESTiTM parameters (38%) than those for sites 3 (knee) and 4 (hip). The data from the big jump, reveal that on a hard surface, the lowest ESTiTM parameters were for sites 1 (toes;46%) and 2 (ankle;27%), compared to values on a soft surface. The speed with which GRFs were transmitted up the leg varied from site to site and also with the type of activity, ranging from undetectable to approx. 60 m/sec. The present study reveals that the ankle joint is exposed to the greatest forces during jumping and running. In addition, this study has confirmed that exercising on a hard surface does indeed increase the stress forces on the toes and ankles. It is interesting to note that the data reveal that toes and ankles absorb most of the GRF during running, while the knee and hip joint remain unaffected, although a more detailed study involving a larger number of subjects and shoe types is now needed.