Methods:
We are using two different systems to study muscle function in horses, one for horses trotting and galloping at a constant speed on a treadmill and
a second system for Dynamic Behaviors such as accelerating, decelerating, or jumping.
The Sonomicrometry System used for Steady-state locomotion on the treadmill involves two computers and two Grass EMG amplifiers. This picture shows a computer on the left (located beneath the polygraph rack) that contains the Sonometrics sonomicrometry system. The analog output of this system is acquired by the computer on the right that contains an A/D card and is running a LabVIEW custom-designed data acquisition system (VI or Virtual Instrument). This VI triggers a bout of data collection by the sono system and our Red Lake Digital camera.
A close-up view of the Sonometrics sonomicrometry system is shown above. The bottom two traces are from a single muscle and are identical. This is because each crystal can function both to send and to receive signals. The top trace is from a second muscle. In this experiment one of the crystals (#3) was not functioning well as a receiver but was still transmitting so that a good signal was available on crystal #4.
The portable data acquisition system on the back of a horse (above) includes the
Sonometrics sonomicrometer and data acquisition system housed in a ruggedized computer. Other parts of the instrumentation pack include a battery powered bio-amplifier and several battery packs. The entire instrument pack weighs about 22 kg, and is comparable to a 10-pound pack being carried by a165 pound person. The portable system is adjusted while the animal is on the treadmill. During set-up and calibration procedures on the treadmill, the computer is powered by an A/C adapter, the black box attached to the rail beside the horse in this picture. When everything is ready for a dynamic trial the A/C adapter is unplugged and the computer switches over to the battery pack attached to the saddle.This picture shows the first recording of muscle length changes during jumping in a large mammal:
We have used this system in one horse to record muscle length changes during acceleration. jumping, and deceleration.