Factors influencing variation in locomotor-respiratory coupling in Standardbred Trotters in the field

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Reasons for performing study:

A close relationship between limb and respiratory rhythms has been shown in clinically healthy galloping horses due to mechanical constraints in the thoracic region. This synchronisation leads to a 1/1 ratio between stride frequency (SF) and respiratory frequency (RF) during galloping. Very little is known about locomotorrespiratory coupling (LRC) during fast trot.


To investigate stride and respiratory rates during a standardised exercise test on the track in Standardbred Trotters.


Forty-four French trotters age 2-10 years performed a standardised exercise test consisting of three 3 min steps at constant speeds. Speed (V) of exercise varied between 500 and 750 m/min. Variables measured during exercise: SF, heart rate, RF using a microphone between the nostrils, blood lactate concentration. Physiological variables V4 and V200 were calculated and race performance index recorded.


There was no age-related difference in RF or in LRC. Two LRC strategies were found: around 1/1 ratio and 3/2 ratio between SF and RF, respectively. A relationship between SF/RF ratio and physiological parameters showed a higher LRC in good performers because of a lower RF during submaximal and maximal exercise.


RF is significantly lower and LRC significantly higher in good compared to poor performers.

Potential relevance:

Investigation is required to ensure that the breathing techniques of trotters may be used in the selection process of racehorses.

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