Electromyographic activity of the long digital extensor muscle in the exercising Thoroughbred horse

Abstract

Summary Surface electrodes were used to record electromyographic (EMG) activity of the long digital extensor muscle on the right hindlimb of 8 Thoroughbred horses for 8 s at the walk and 8 s at the trot before (unfatigued) and after (fatigued) an exercise test. The exercise test was performed on a motorised treadmill set on a 10% grade. Each test started at a speed of 6 m/s which was increased by 1 m/s each minute until the horse fatigued as indicated by its inability to keep pace with the treadmill with minimal encouragement. Observations were made on the horses prior to conditioning (untrained state) and after 8 weeks of regular exercise (trained state). The mean root‐mean‐square (rms) values of EMG bursts collected in each experimental trial were determined for each horse and group means were derived from the mean of independent subjects. Statistical comparisons for differences in rmsEMG were related to gait, fatigue and training. Mean rmsEMG at the trot was consistently higher than at the walk (P<0.05). At the walk, mean fatigued rmsEMG tended to be higher than the mean unfatigued rmsEMG in the untrained state and was significantly higher in the trained state (P<0.05). At the trot, mean fatigued rmsEMG was higher (P<0.05) than mean unfatigued rmsEMG in both the untrained and trained states. Training did not have an effect on mean rmsEMG of unfatigued muscles at the walk or the trot (P>0.05). However, fatigued muscles experienced higher EMG activity in the trained state at the walk (P<0.05). A similar tendency was observed at the trot. Results of this study suggest that surface EMG measurement may be useful for evaluating fatigue in exercising horses.

The effect of cut-off frequency when high-pass filtering equine sEMG signals during locomotion

“…A cut-off frequency range of 30 -40 Hz is in agreement with previous equine sEMG studies that report using a HPF with a 40 Hz cut-off (Cheung et al, 1998;Kienapfel, 2015;Kienapfel et al, 2018), but do not provide a justification for why this cut-off frequency was chosen. Findings from this study indicate that, while previously employed cut-off frequencies of 10 and 20 Hz (Hodson-Tole., 2006;Crook et al, 2010;Harrison et al, 2012) are more likely to preserve the low-frequency component of the equine sEMG signal, they are not appropriate for completely attenuating the noise components.…”

Surface electromyography in animal biomechanics: A systematic review

“…The earlier work on sEMG in animals in the 1990’s performed by Janssen et al (1992) and Cheung et al (1998) investigated horses; this included a group of Thoroughbreds and a mixed group of ponies without any further details regarding breed given. These studies were pioneering, as prior to the work by Janssen et al (1992), assessment of muscle activity in horses had only been performed using intramuscular EMG (e.g.…”

The effects of treadmill inclination and speed on the activity of two hindlimb muscles in the trotting horse

“…Kinematic investigations (Leach and Drevemo 1991;Rooney et al 1991;Kai et al 1997;Sloet et al 1997) and exercise physiology studies (Barrey et al 1993; Hiraga et al 1 9 9 5 ; R a t z l a ff et al 1995) have been previously conducted on the eff e c t of the speed and inclination of the treadmill. Electromyographic activity of several muscles during different gaits has been documented in horses on track and treadmill (Wentink 1978;Tokuriki and Aoki 1995;Cheung et al 1998; Robert et al 1 9 9 8 ) .…”