WATER TREADMILL EXERCISE FOR HORSES
Water treadmills have become more popular within the last 10-15 years. Exercise on a water treadmill can be incorporated into the training programmes of competition horses or used for rehabilitation following injury. Horses can walk or trot on a water treadmill with most models allowing the water depth to be altered within the exercise session between the level of the fetlock and the shoulder depending on the aims for the exercise session. Horses work on a treadmill for about 20 minutes each session. Water presents both drag and buoyancy, which result in an alteration in gait compared with normal walking overland and which may have benefits for the management of certain musculoskeletal conditions such as osteoarthritis (King et al. 2013).
Water is more viscous than air and so it is harder to move through water than air due to the frictional and drag forces due to the water. The higher the water, the greater the drag force. If the horse doubles the speed of the limbs through the water, the drag force is quadrupled; so the speed that is comfortable for a horse moving on a treadmill belt submerged in water is slower than would be comfortable on an ordinary treadmill or overland. The higher the water, the greater the reduction in weight bearing due to buoyancy. Water which only covers the limbs and does not reach the horse’s belly will provide less than 10% reduction in weight bearing. Water at the level of the point of the shoulder is estimated to produce a 30% reduction in weight bearing whereas water up to the level of the pelvis produces a 75% reduction in weight bearing (McClintock et al. 1987).
As the water depth increases, the horse adopts a different gait in water compared to walking on a dry belt such that there is a relative decrease in the stride rate (Scott et al. 2010) and an increase in range of movement of the lower limb joints (Mendez-Angulo et al. 2013) and an increase in flexion and rotation of the back (Mooij et al. 2013). Despite the differences in gait pattern between water treadmill and overland exercise, the responses to the exercise as measured using heart rates and blood lactate levels (Lindner et al. 2012) is equivalent to walking or trotting overland and is low intensity exercise fuelled by aerobic energy production. Even trotting in high water doesn’t produce heart rates as high as those recorded during swimming or galloping (up to 200 beats/min).
Treadmill exercise gives the trainer the ability to control the intensity (given by speed/incline or water depth) and duration of exercise. The intensity and/or duration can be increased progressively throughout the course of a rehabilitation programme. Water treadmill exercise is an attractive option for trainers seeking to add variety to a horse’s work programme or to manage a horse recovering from injury. As with any injury, it is advisable to work closely with your vet to devise a suitable rehabilitation programme.
Water Treadmill Case Study National Hunt Racehorse with left fore lameness
Diagnosis: Mid-carpal joint synovitis and third carpal bone sclerosis.
Treatment: Intra-articular corticosteroid injection.
Rehabilitation: Acclimated to walking on the ordinary treadmill (a Sato high speed treadmill) for 15 minutes twice daily before starting regular work on the water treadmill one week later. The first three sessions in the water treadmill consisted of gradually increasing the depth of the water up to the level of the stifle whilst walking at a speed of about 0.8 m/s. He quickly progressed to walking in stifle depth water for 15 minutes twice daily, building to 2 x 20 minutes prior to discharge one month later. Outcome: Racing again 1 month post discharge and has been successful in Grade 1 jump races since.
Water Treadmill Exercise
1.What is Archimedes principle?
2.What is the approximate stride frequency (strides/sec) of the horse walking in the water treadmill in the video (hint: watch 10 strides).
3.How does the stride alter as water height increases?
4.Do you think you could prepare a horse for racing by working in a water treadmill?
5.What do the following terms mean:
c. Stride length