Surface electromyography (sEMG) of equine core muscles and kinematics of lumbo-sacral joint during core strengthening exercises

Dynamic Mobilisation Exercises (DME) and myotatic reflex exercises were developed with the aim of improving core strengthening in horses. Previous studies have shown DME can increase cross sectional area (CSA) and symmetry of multifidus muscle, as well as activating the external oblique abdominal, and superficial descending pectoral muscles. The aim of this study was to objectively measure activity differences in m. longissimus dorsi (LD) and m. rectus abdominus (RA) whilst performing three levels of spinal flexion and lateral bending, as well as comparing thoracic and pelvic lift exercises in nine adult sport horses. Three repetitions of each exercise was performed for five seconds. Surface electromyography (sEMG) was used to record muscle electric activity, whilst sagittal lumbo-sacral flexion was measured with kinematics analysis. Overall, the results have shown that spinal flexion and lateral bending activate the m. rectus abdominis (RA) progressively as the exercise requires further reach, with a lateral bending effect evident on the ipsilateral side of RA. RA also had increased activation during thoracic lifts in comparison with pelvic lifts. M. longissimus dorsi (LD) has shown no significant differences in peak or average rectified EMG measures on the contralateral side during lateral bending. Pelvic lifts generated the greatest flexion of the lumbo-sacral (LS) joint. Results provide a guideline of the level of muscle effort required in relation to each exercise.</p

Opening forces or failure of commercially available equine headcollars and other safety devices

A recent survey by the authors of the present study indicated that headcollar (halter, USA) related incidents resulting in horse injuries may be common. From the survey, 134 incidents involving horse fractures and 167 fatalities were reported. Headcollar design and materials vary markedly from traditional leather to “safety” headcollars and safety devices. Despite their almost universal use, there has been minimal study as to how these items function or specifications for performance. The aim of the present study was to select a range of commercially available standard headcollars and a number of safety devices, to test the force required to break or release them. Safety devices selected included baler twine, which is widely used by equestrians to attach a horse by a headcollar to a lead rope and in turn to a fixture. This system practice is perceived to increase safety. Devices were subjected to increasing load in the poll to lead-rope attachment axis (i.e. to simulate a horse pulling backward) using a custom-made steel rig incorporating an electric 1000 kg winch. The force was increased incrementally until either the headcollar or device opened or failed. The lowest mean opening force of 357 ± 50 N was for a safety headcollar, which is equivalent to a load of approximately 36 kg. The highest breaking force was 5798 ± 265 N for one of the eight different webbing headcollars tested. Breaking for safety devices ranged from 354 ± 121 N for “fine” baler twine to 1348 ± 307 N for a “heavy duty” baler twine. Variability in opening force was lowest in two of the webbing headcollars (CV 3500 N). The greatest variability was found for fine baler twine (CV = 34%) and one of the commercial safety devices (CV = 38%). The range of opening forces and variability in opening forces for standard headcollars, safety headcollars and safety devices is a cause for concern and may give horse owners/handlers a false sense of security with regards to safety, and actually predispose horses and handlers to an increased risk of injury.</p

The Wnt5a Receptor, Receptor Tyrosine Kinase-Like Orphan Receptor 2, Is a Predictive Cell Surface Marker of Human Mesenchymal Stem Cells with an Enhanced Capacity for Chondrogenic Differentiation

Multipotent mesenchymal stem cells (MSCs) have enormous potential in tissue engineering and regenerative medicine. However, until now, their development for clinical use has been severely limited as they are a mixed population of cells with varying capacities for lineage differentiation and tissue formation. Here, we identify receptor tyrosine kinase-like orphan receptor 2 (ROR2) as a cell surface marker expressed by those MSCs with an enhanced capacity for cartilage formation. We generated clonal human MSC populations with varying capacities for chondrogenesis. ROR2 was identified through screening for upregulated genes in the most chondrogenic clones. When isolated from uncloned populations, ROR2+ve MSCs were significantly more chondrogenic than either ROR2–ve or unfractionated MSCs. In a sheep cartilage-repair model, they produced significantly more defect filling with no loss of cartilage quality compared with controls. ROR2+ve MSCs/perivascular cells were present in developing human cartilage, adult bone marrow, and adipose tissue. Their frequency in bone marrow was significantly lower in patients with osteoarthritis (OA) than in controls. However, after isolation of these cells and their initial expansion in vitro, there was greater ROR2 expression in the population derived from OA patients compared with controls. Furthermore, osteoarthritis-derived MSCs were better able to form cartilage than MSCs from control patients in a tissue engineering assay. We conclude that MSCs expressing high levels of ROR2 provide a defined population capable of predictably enhanced cartilage production.</p