Placement of a small sensor on the suspensory ligaments can be used to record the GRF signal of hoof impact with the ground as it travels up the limb. The S-score of this signal can then be used to assess the functional health of the suspensory ligaments.
Here is a typical healthy PSL signal
Here is a typical injured PSL signal
Note that with increasing level of physical activity the recorded AMG signal not only increases in amplitude (spatial summation) but also becomes more intense (temporal summation).
Here are muscle signals recorded from young racehorses whilst being trained.
Note that both muscles show a decrease in ESTi-Score with increasing work intensity (upper panels) from first walking out to the track, to trotting to a short period of gallop.
Then as the horses move back to a cool down trot and a walk back to the stables, the ESTi-Score recovers (immediately for m.Gluteus medius and during the walk for m.Semitendinosus).
The lower panels (previous image) show the balance score for the left versus right sides of the horses – note that for m.Semitendinosus that there is an imbalance after the gallop and that this first improves during the walk back to the stables – this imbalance is an early sign of muscle fatigue.
These recordings can be used to fine-tune training sessions and help trainers to avoid over-training issues.
When a muscle is over-worked and becomes damaged, swollen and painful the AMG signal looks like this. The figure above is for m.Gluteus medius during short periods of walking from an over-exercised race horse – note how the signal is rather intense for walking, and that it does not completely disappear between bouts of physical activity (a typical signal from a painful muscle).