Equine Exercise Physiology Flashcards

Vocabulary flashcards about Equine Exercise Physiology.

Aerobic Capacity

The horse has a large aerobic capacity and physiological responses to exercise to increase oxygen transport within the body. Measured as VO2 max; maximal oxygen consumption.

Integrated Chain of Performance

Optimal performance requires complex interactions between multiple body systems including the cardiovascular, respiratory, and musculoskeletal systems.

Equine Musculature Composition

About 55% of the thoroughbred body weight is comprised of skeletal muscle.

Endurance Horse Muscle Fibers

Endurance horses have more slow‐twitch Type 1 muscle fibres which have a higher oxidative capacity.

Thoroughbred Muscle Fibers

Thoroughbreds have proportionally more fast‐twitch Type IIa muscle fibres which have the greatest anaerobic capacity and thus may contribute to greater lactate accumulation.

Muscle Adaptations to Training

Muscle adapts to aerobic training by increases in muscle capillarity density, the density and size of mitochondria and enhanced oxidative enzymatic activity, increasing the capacity for oxygen extraction and consumption.

Sprint Racing Energy Production

Horses that compete in sprint racing events rely primarily on anaerobic metabolism including energy released from glucose/glycogen and hydrolysis of phosphocreatine

Mid-Distance Energy Production

Horses performing in mid-distance events rely on stored ATP and phosphocreatine, shifting to aerobic energy production, and using anaerobic glycolysis for up to 30% of energy.

Endurance Horse Energy Production

Endurance horses rely primarily on aerobic metabolism, which is efficient and sustainable as long as nutrients are available.

Obligate Nasal Breathers

Horses are obligate nasal breathers due to an extended soft palate; they compensate by flaring their nostrils during exercise.

Locomotory-Respiratory Coupling (LRC)

Horses synch their breathing rate and stride frequency. Every time they take a stride, they take a breath.

Minute Ventilation

The amount of air that is breathed in and out per minute. Higher in horses than humans.

Splenic Contraction

At the onset of strenuous exercise, the smooth muscle fibres in the capsule of the spleen receive sympathetic stimulation, causing the spleen to contract, releasing extra red blood cells into the circulation, increasing the PCV.

Hypoxemia

A low concentration of oxygen in arterial blood.

Hypercapnia

An excess amount of CO2 in the blood.

Pulmonary Function Limitations

Pulmonary function becomes the limiting factor for the horses’ performance capacity.

Clinical Exercise Tests

Exercise tests that are used for diagnostic purposes.

Performance Exercise Tests

Exercise tests that provide insight into a horses’ physical condition, and can be a valuable, objective tool to validate or assess training programs.

V̇O2max

Maximal oxygen consumption; this is considered to be the reference technique for determining cardiorespiratory fitness.

Cardiac Output

The most important determinant of V̇O2max, due to an increase in stroke volume rather than in heart rate; increases the maximal oxygen consumption due to improved oxygen delivery to tissues.

Big Respiratory Cycles (BRC)

Galloping horses intermittently have ‘big respiratory cycles’ in which the 1:1 ratio between stride and respiration is transiently decoupled. This results in a tidal volume of almost 30L over 2‐3 strides.

Recurrent Laryngeal Neuropathy

A performance limiting neurological condition causing the horse to lose the ability to fully open the left side of the larynx during exercise, limiting airflow to the lung

High-Intensity Warm-Up Effects

A high‐intensity warm‐up accelerates oxygen consumption kinetics leading to vasodilatation, increased H+, and increased pulmonary arterial temperature. Horses have lower lactate production, with a significantly decreased blood lactate accumulation rate.

Lactate

A product of anaerobic metabolism produced from pyruvate faster than the capacity of clearance/consumption mechanisms.

Anaerobic Threshold

The level of work at which lactate starts to accumulate in the blood. In humans, this is defined as the speed at which lactate reaches 4mmol/L.

Maximum Heart Rate in Horses

Max HR does not adapt in response to training and is not considered a good marker of fitness, but it is unique to each horse, decreasing slightly as the horse ages, and allows evaluation of the difficulty of work completed.