Exercise capacity in young and old mares.

This research study focuses on the comparison of exercise capacity between young and older mares, examining parameters such as aerobic capacity and work rate, and demonstrates that older mares have significantly reduced maximal aerobic capacity compared to their younger counterparts.

Study Overview

• The study was conducted to investigate the hypothesis that compared to young unfit horses, older unfit horses might have decreased aerobic capacity and other indices associated with exercise capacity.
• This study involved 6 young (approximately 5.3 years old) and 6 aged (around 22.0 years old) healthy Standardbred and Thoroughbred mares.
• The mares used in the study were all familiar with running on a treadmill and had not received any exercise training for at least 4 months prior to the study.

Methodology

• The mares were subjected to an incremental exercise test wherein they ran up a fixed 6% grade, starting at a speed of 4 m/s, with the speed increasing 1 m/s every 60 seconds.
• The test continued until the mares reached fatigue.
• Maximal oxygen uptake (VO2max) was measured using an open-flow calorimeter, a device that measures the amount of heat produced by a chemical reaction or physical change.
• During the last 10 seconds of each step of the test, venous blood samples were collected and used to measure blood lactate concentration and Packed Cell Volume (PCV).
• Key performance indices such as velocity at VO2max, maximal velocity, and velocity at a lactate concentration of 4 mmol/L were calculated. The work rate at these velocities was also determined.

Results

• The study found significant differences between old and young mares for factors such as maximal run velocity attained during the test, VO2max, and velocity at VO2max.
• The velocity required to reach a blood lactate concentration of 4 mmol/L was lower in old mares compared with young mares.
• These results led to the conclusion that older mares have a substantially lower (-24%) maximal aerobic capacity than young mares.

Conclusions

• Given that many horses participate in athletic activities well into their late teens and even beyond 20 years of age, there is a need to modify training programs to adjust to the changing physical capabilities of older horses.
• The study highlights the importance of understanding the effect of age on exercise capacity in horses. This is crucial for devising appropriate training regimes for horses of different ages.