Search

The reliability of surface electromyography (sEMG) has not been adequately demonstrated in the equine literature and is an essential consideration as a methodology for application in clinical gait analysis. This observational study investigated within-session, intra-subject (stride-to-stride) and inter-subject reliability, and between-session reliability of normalised sEMG activity profiles, from triceps brachii (triceps), latissimus dorsi (latissimus), longissimus dorsi (longissimus), biceps femoris (biceps), superficial gluteal (gluteal) and semitendinosus muscles in n = 8 clinically non-lame horses during in-hand trot. sEMG sensors were bilaterally located on muscles to collect data during two test sessions (session 1 and 2) with a minimum 24-hour interval. Raw sEMG signals from ten trot strides per horse and session were DC-offset removed, high-pass filtered (40 Hz), full-wave rectified, and low-pass filtered (25 Hz). Signals were normalised to peak amplitude and percent stride before calculating intra- and inter-subject ensemble average sEMG profiles across strides for each muscle and session. sEMG profiles were assessed using waveform similarity statistics: the coefficient of variation (CV) to assess intra- and inter-subject reliability and the adjusted coefficient of multiple correlation (CMC) to evaluate between-session reliability. Across muscles, CV data revealed that intra-horse sEMG profiles within- and between-sessions were comparatively more reliable than inter-horse profiles. Bilateral gluteal, semitendinosus, triceps and longissimus (at T14 and L1) and right biceps showed excellent between-session reliability with group-averaged CMCs > 0.90 (range 0.90–0.97). Bilateral latissimus and left biceps showed good between-session reliability with group-averaged CMCs > 0.75 (range 0.78–0.88). sEMG profiles can reliably describe fundamental muscle activity patterns for selected equine muscles within a test session for individual horses (intra-subject). However, these profiles are more variable across horses (inter-subject) and between sessions (between-session reliability), suggesting that it is reasonable to use sEMG to objectively monitor the intra-individual activity of these muscles across multiple gait evaluation sessions at in-hand trot. [ABSTRACT FROM AUTHOR]

Background Previous studies have validated methods for determining kinematic gait events using threshold-based techniques. However, a simple method that can be successfully applied to walk, trot and canter is yet to be identified. Objectives To develop a simple kinematic method to identify the timing of hoof contact (hoof-on), peak vertical force and lift off (hoof-off), which can be applied in walk, trot and canter. Study design In vivo method authentication study. Methods Horses (n = 3) were ridden in walk, trot and canter down a runway on which four force plates were arranged linearly. Three-dimensional forces were recorded at a sampling rate of 960 Hz and were synchronised with a 10-camera motion analysis system sampling at 120 Hz. Events identified from vertical ground reaction force ( GRFz) data were hoof-on (GRFz>50N), peak vertical force ( GRFzpeak) and hoof-off (GRFz<50N). Kinematic identification of hoof-on and hoof-off events was based on sagittal planar angles of the fore- and hindlimbs. Peak metacarpophalangeal ( MCP)/metatarsophalangeal ( MTP) joint extension was used to assess the time of GRFzpeak. The accuracy (mean) and precision (s.d.) of time differences between kinetic and kinematic events were calculated for fore- and hindlimbs at each gait. Results Hoof-off was determined with better accuracy (range: −3.94 to 8.33 ms) and precision (range: 5.43-11.39 ms) than hoof-on across all gaits. Peak MCP angle (range: 5.83-19.65 ms) was a more precise representation of GRFzpeak than peak MTP angle (range: 11.49-67.75 ms). Main limitations The sample size was small and therefore further validation is required. The proposed method was tested on a single surface. Conclusions This study proposes a simple kinematic method of detecting hoof-on, hoof-off and GRFzpeak at walk, trot and canter. Further work should focus on validating the methodology in a larger number of horses and should extend the method for use on surfaces with varying levels of compliance. [ABSTRACT FROM AUTHOR]

Synovitis is a common feature of osteoarthritis (OA). Exogeneous intra-articular inflammatory compounds such as lipopolysaccharide or interleukin 1β (human or equine) produce a convenient, self-limiting, and reversible synovitis in horses, which can be useful to evaluate putative OA interventions. Although biochemical responses to this minimally invasive synovitis model have been described, its effects on functional adaptations in movement remains unclear. The aim of this pilot study was to correlate synovial fluid biochemical responses to intra-articular injection of recombinant equine IL-1b (IL-1) with objective measures of movement asymmetry. Horses (n = 3) randomly received 0, 50 or 75ng reIL-1 in 500μL of sterile saline into the left or right intercarpal joint in a 3-way crossover design, with 50 and 75ng treatments applied to the contralateral carpus and 24 h between treatments. Synovial fluid was collected by aseptic arthrocentesis at 0 (before IL-1 injection), 6, 12 and 24 h after IL-1 injection and analyzed for prostaglandin E 2 (PGE 2) by ELISA. To quantify movement asymmetry, MinDiff was calculated using withersvertical displacement data (2000 Hz) acquired from an inertial measurement unit (IMU) (Delsys Trigno) during in-hand trot trials at each time point/condition. PGE 2 and MinDiff data were analyzed using 2-way repeated measures ANOVA with respect to IL-1 challenge dose and time. Correlations between variables were determined using the Spearman correlation. PGE 2 significantly increased at 6 h (314.4 ± 136.4 pg/mL) compared with 0 h (128.0 ± 43.2 pg/mL) following challenge with 75ng IL-1 (P = 0.04). An increase in MinDiff 6 h following 75ng challenge was not significant (P = 0.13). MinDiff and PGE 2 peaked simultaneously at 6 h after injection of 75ng IL-1, but the correlation was not significant (P = 0.27). Data from this small pilot study indicate that low intra-articular dose of reIL-1b induces measurable increase in local synovial fluid PGE 2 , which is a key pro-inflammatory biomarker. Effects on adaptations in gait asymmetry warrant further investigation. [ABSTRACT FROM AUTHOR]

The horse's ability to execute the diverse physical demands of jumping is greatly influenced by muscular adaptations to training. The aim of the study was to provide preliminary insight into potential differences in the functional activity of muscles recruited during phases of the equine jumping effort. An exploratory case study was conducted to investigate muscle activity and recruitment in one jumping horse, experienced in 1.40 m competition. Wireless sEMG electrodes were utilised to quantitatively investigate the degree of muscle activation by recording potentials from the Superficial gluteal (SG), Triceps brachii (TB) and Longissimus dorsi muscles. Data were collected as the horse executed a related combination of fences with a maximum height of 1.25 m. Mean motor unit action potential (mMUAP) and mean peak amplitude frequency (PAF) were determined for each muscle during approach, jump and intermediate strides, and were analysed using Friedman and Wilcoxon Signed Rank tests to establish whether significant differences occurred between strides. Statistical analyses did not reveal significant differences between mMUAP values for muscles investigated across strides (P≯0.05). However, significant differences were found for mean PAF values in the left SG between approach and jump strides (P<0.025), and between jump and intermediate strides (P<0.025) in the left TB. The lack of significant differences between strides may reflect the theory that the jump stride is a form of extended suspension incorporated into the canter stride and may support current anecdotal training methods of the jumping horse, which place emphasis on developing a regular and collected canter. However, results from this study were based on one horse and therefore application to the wider population of jumping horses should be undertaken with caution until further research in more subjects is conducted to support the results from this preliminary study. [ABSTRACT FROM AUTHOR]

The article presents a reproduction of the paper "England and the United States," by the 19th-century Kentucky-based political writer Duff Green, and discussion of its historical context. A brief biographical sketch of Green's life is provided, noting his business and political ventures. Introductory comments are given describing the events of the Quintuple Treaty of 1841, in which several major European nations abolished and agreed to oppose the slave trade, its depiction throughout several international newspapers, and the popular opposition to it by some within the United States.