Principal component analysis, using the measurements during running and swimming test, in thoroughbred horses

A survey of trainers on the use of swimming and other water-based exercise for Thoroughbred racehorses in Australia

We aimed to determine the extent of use of water-based exercise and to describe swimming training practices in Thoroughbred racehorses in Victoria, Australia. A convenience sample of 118 trainers were interviewed, information relating to swimming protocols, perceived benefits and contra-indications, and use of other water-based exercise recorded and descriptive data analyses performed. Water-based exercise was used by 85.6% (n=101) trainers: 82.2% (n=97) swimming, 25.4% (n=30) using a water walker, 13.6% (n=16) incorporating ridden trotting (‘surging’) exercise in chest deep water, and 1.7% (n=2) using an underwater treadmill. Common reasons (and trainer %) for swimming were training variety and mental ‘freshness’ (62.9%), part of the exercise regime on ‘slow’ days (61.9%) and fitness benefits (60.8%). These horses swam a median of 50-90 m (ranging from a minimum of 40-180 m to a maximum of 40-450 m), continuously or as intervals, after track work, once or twice daily a median 3 days/week (range 0.5-7). Swimming for 50 (range 40-120 m) to 90 m (range 40-200 m) before track work 7 days/week (range 3-7) was used by 43 of the 97 trainers (44.3%) to manage horses prone to exertional rhabdomyolysis. Swimming was used to replace fast work by three trainers who swam horses with limb injuries up to 270-450 m. Common reasons (and % trainers) for not swimming individual horses were demeanour/distress (73.2%), previous swim colic (35.1%) or exercise induced pulmonary haemorrhage (35.1%) although only five trainers had ever seen epistaxis after swimming exercise. Swimming is widely used in training Thoroughbred horses in Australia yet trainer opinions particularly on fitness benefits, contra-indications and protocols vary widely and need to be scientifically validated. Diversifying training activities is a common strategy for managing racehorses in training, yet a better understanding of the best use of swimming and other cross-training options is needed so that evidence-based recommendations can be made.

EMG activity of the muscles of the neck and forelimbs during different forms of locomotion

We recorded the electromyographic (EMG) activity of 7 skeletal muscles in the forequarters and 1 in the hindquarters of 6 Thoroughbred horses during overground walking, swimming in a circular pool, and walking and trotting in a water treadmill. Bipolar fine wire electrodes were inserted into the muscles and the EMG signals were recorded using a telemetric system. The splenius exhibited tonic EMG activity during swimming. The brachiocephalicus showed its highest intensity during swimming followed by the walk and trot in the water treadmill and then walking overground. The triceps brachii caput longum had a similar activity pattern to the brachiocephalicus. The brachialis showed only weak EMG activity in all 3 types of locomotion. The extensor digitorum communis had higher intensity of EMG activity in the walk in the water treadmill than in other kinds of locomotion. The flexor digitorum profundus exhibited the most intense EMG activity during swimming. These results indicated that swimming evoked strong EMG activity in the antigravity muscles in spite of reduced gravitational force. Walking in the water treadmill may require more intensified EMG activity of the forelimb than the trot in the same treadmill.