The influence of different exercise regimens on the development of locomotion in the foal

To study the influence of different exercise regimens on the development of locomotion, 40 Warmblood foals aged 1 week were subdivided into 3 groups: box-rest, training and pasture exercise. The box-rest group remained for 24 h a day in a box stall while the training group was housed similarly, but additionally received a 30 min workout with gallop sprints 6 times a week. The pasture group served as a control group and was kept at pasture for 24 h a day. After 5 months, the locomotion pattern at the trot of every foal was recorded overground with a 2-D MacReflex gait analysis system. A randomly selected group of 19 foals was recorded again at age 11 months after they had been kept in an open loose box with access to a small paddock without any specific training for 6 months duration. At 5 months of age the box-rest group moved with a more protracted forelimb, and more extended shoulder and elbow joints than the pasture group. Carpal and fetlock joint kinematics were rather similar in all groups. In the hindlimb, the box-rest foals were significantly different from the other 2 groups, reflected in a more retracted hindlimb, more hip extension, more flexed stifle and tarsal joints, and a larger maximal flexion of hip, stifle, tarsal and fetlock joints. In the simultaneous video recordings this locomotion pattern was visible as a hypermetric movement. The larger protraction in the forelimb and retraction in the hindlimb, as seen in the box-rest group, is opposite to the interlimb coordination of a superior moving horse. The pastured foals had a smaller range of motion of the shoulder and hip joint and less maximal step height of both fore and hind hooves, while the velocity and step length were similar between the 3 groups. Pastured foals could trot the same distance with less joint motion and therefore had a more efficient intralimb coordination. The training group moved in a way comparable with the box-rest group in the similar velocity box-rest foals trot with an abnormal, hypermetric and therefore inefficient and poorer locomotion pattern. When, superimposed on box-rest, exercise is provided in the form of gallop sprints, this will mainly improve the hindlimb locomotion. These induced differences in locomotion pattern of foals can be reversed when the foals afterwards are subjected to the same exercise regimen again.