ECC Biomechanics & Movement Analysis 3 — Questions and Answers
Question 1: Which of the following best describes 'impulsion' in equine movement from a biomechanical standpoint?
- Maximum forward speed generated by the hindlimbs
- Stored elastic energy in the hindlimb tendons released during propulsion
- The desire to move forward combined with engagement and thrust from the hindquarters (Correct answer)
- Suspension phase duration during the trot
Correct answer: The desire to move forward combined with engagement and thrust from the hindquarters
Impulsion is the biomechanical and neuromuscular quality of hindquarter engagement, thrust, and forward energy — not merely speed.
Question 2: A horse displaying a 'stabbing' forelimb action where the hoof contacts the ground toe-first is most likely compensating for pain in which region?
- Cervical vertebrae
- Thoracic dorsal spinous processes
- Palmar foot structures or navicular apparatus (Correct answer)
- Sacroiliac joint
Correct answer: Palmar foot structures or navicular apparatus
Toe-first landing is a classic compensation for palmar foot pain (e.g., navicular syndrome), where the horse avoids heel-first impact to reduce pressure on sensitive caudal foot structures.
Question 3: What does 'over-track' measure during gait analysis and what is its clinical significance?
- How far the hindfoot lands ahead of the forefoot print, indicating hindlimb engagement and lumbar mobility (Correct answer)
- The degree to which the fore hoof crosses the midline during protraction
- How much the horse's stride length exceeds breed standards
- The arc height of hindlimb flight path during the swing phase
Correct answer: How far the hindfoot lands ahead of the forefoot print, indicating hindlimb engagement and lumbar mobility
Over-track quantifies how far ahead of the ipsilateral forehoof print the hindhoof lands, serving as a practical measure of hindlimb engagement and thoracolumbar flexibility.
Question 4: The 'swinging' (oscillating) motion of the equine head and neck during the walk primarily serves which biomechanical function?
- Increases visual field by elevating the head at each stride
- Acts as a pendulum counterbalancing thoracolumbar rotation and aids forelimb protraction (Correct answer)
- Cools the cervical musculature by increasing airflow
- Maintains vestibular equilibrium during lateral weight shifts
Correct answer: Acts as a pendulum counterbalancing thoracolumbar rotation and aids forelimb protraction
The pendulum-like head and neck oscillation during the walk counterbalances spinal rotation and actively assists forelimb protraction through inertial coupling.
Question 5: When performing a dynamic flexion assessment at the trot, a positive response is characterized by:
- Increased stride length immediately after limb release
- Worsening of lameness (increased asymmetry) during the first 4–8 trot strides after flexion (Correct answer)
- Refusal to trot following any limb flexion
- Reduced weight-bearing on the contralateral limb
Correct answer: Worsening of lameness (increased asymmetry) during the first 4–8 trot strides after flexion
A positive flexion test shows exacerbated lameness (increased head nod or hip hike) during the first several trot strides after releasing the flexed limb.
Question 6: In the context of equine chiropractic assessment, a 'vertebral subluxation complex' (VSC) most accurately refers to:
- A complete dislocation of a spinal vertebra confirmed on radiograph
- A functional joint dysfunction with altered motion, pain, and neurological influence without complete dislocation (Correct answer)
- A fracture of the articular process detected by palpation
- Muscle atrophy secondary to spinal cord compression
Correct answer: A functional joint dysfunction with altered motion, pain, and neurological influence without complete dislocation
A VSC is a functional segmental dysfunction characterized by altered joint motion, local pain, muscle hypertonicity, and potential neurological effects — not a frank dislocation.
Question 7: Which measurement tool is most commonly used in research to objectively quantify equine hindlimb lameness asymmetry?
- Force plate analysis of peak vertical force
- Inertial measurement unit (IMU) body-mounted sensor systems (Correct answer)
- Video gait analysis at slow-motion replay
- Visual lameness scoring on a 0–5 AAEP scale
Correct answer: Inertial measurement unit (IMU) body-mounted sensor systems
IMU-based systems (e.g., Lameness Locator) provide objective, repeatable quantification of pelvic and head movement asymmetry that correlates with lameness grade.
ECC Biomechanics & Movement Analysis 3
Which of the following best describes 'impulsion' in equine movement from a biomechanical standpoint?