Factors influencing variation in locomotor-respiratory coupling in standardbred trotters in the field.

This research study investigates the relationship between stride and respiratory rates (locomotor-respiratory coupling or LRC) in racing horses, specifically Standardbred Trotters, during a standardised exercise test. The study discovered two LRC strategies and showed that good performing horses had lower respiratory frequencies and higher LRC.

Methods and Participants

• The study includes 44 French Standardbred Trotters aged between 2-10 years.
• A standardised exercise test was carried out with these horses, which involves three steps each of three minutes at constant speeds. The speed differed between 500 and 750 m/min.
• Different variables were measured during these exercises include stride frequency (SF), heart rate, respiratory frequency (RF) using a microphone placed between the nostrils, and blood lactate concentration.
• Further, two physiological variables, V4 and V200, were also calculated, and a race performance index was recorded.

Results

• The study found that there were no significant differences in RF or in LRC attributable to the age of the horses.
• Two LRC strategies were discovered by the researchers, with one showing a 1 to 1 ratio between SF and RF, the other presenting a 3 to 2 ratio between SF and RF.
• An important finding was the relationship between the SF/RF ratio and physiological parameters, showing that higher performing horses had higher LRC due to lower RF during both submaximal and maximal exercises.

Conclusions

• The study conclusively showed that the RF is significantly lower and the LRC is significantly higher in better-performing horses compared to poorer performers.
• Thus, the researchers point out the importance of further investigation into the breathing techniques of trotters for consideration in the selection process of racing horses.