Water Treadmill Exercise Research Articles

Kinematic Responses to Water Treadmill Exercise When Used Regularly within a Sport Horse Training Programme: A Longitudinal, Observational Study.

Repeated exposure to water treadmill (WT) exercise could elicit kinematic responses reflecting adaptation to WT exercise. The study's aim was to compare the responses of a group of sport horses to a standardised WT exercise test (WTSET) carried out at three time points, week 0 (n = 48), week 20 (n = 38), and week 40 (n = 29), throughout a normal training programme incorporating WT exercise. Horses were recruited from the existing client populations of two commercial water treadmill venues for the purpose of this longitudinal, observational study. Limb, back, poll, wither, and pelvic kinematics were measured during the WTSET using videography, optical motion capture, and inertial motion sensors. Forelimb and hindlimb protraction increased (p < 0.001 for both), and forelimb and hindlimb retraction decreased (p < 0.001 for both) at week 40 compared to week 0. Caudal thoracic flexion-extension and lateral bend ranges of movement were greater at week 40 compared to week 0 (p < 0.001 and p = 0.009, respectively). Increased training speed was associated with increased craniocaudal poll movement (p = 0.021), decreased forelimb protraction (p = 0.008), and increased forelimb retraction (p = 0.021). In addition to characteristic changes in kinematics due to increasing water depth, regular WT exercise resulted in kinematic adaptation to movement in water. Factors such as the frequency of WT sessions and the type of session used with respect to depth and speed were seen to influence the nature of the adaptation. The results suggest that WT exercise sessions could be designed in accordance with specific training goals when used within a normal sport horse training programme.

Effect of speed and water depth on limb and back kinematics in Thoroughbred horses walking on a water treadmill

Water treadmill (WT) exercise may induce limb and back kinematics that meet specific training and rehabilitation goals. The study aimed to investigate the effects of walk speed, at different water depths (WDs), on limb and back kinematics of six Thoroughbreds exercising on a WT. Horses walked at 2.8/4.3/5.5/6.0 km/h (i.e. 0.8/1.2/1.5/1.7 m/s) at dry, metacarpophalangeal and carpal WD. Videography captured limb movement in the sagittal plane. Motion-capture measured thoracolumbosacral flexion-extension (FE), and lateral bend (LB) ranges of movement (ROM) using skin surface markers on the sixth, tenth, thirteenth, eighteenth thoracic, third and fifth lumbar, and third sacral spinous processes. Inertial-motion-sensors measured poll, withers and pelvic displacements. Following preliminary univariable analyses, multivariable mixed-effects linear-regression analyses were used to examine the relationship between speed, WD and each outcome variable (P < 0.05). Peak metacarpophalangeal, carpal and tarsal joint flexion increased with speed (P ≤ 0.002) and depth combined (P 0.001) while peak metatarsophalangeal flexion increased with WD only (P 0.001). Thoracolumbar FE-ROM between T10 and L3 and hindlimb retraction was increased by speed and WD combined (P 0.001). Hindlimb protraction was increased by speed (P 0.001) while hindlimb retraction was increased by speed and WD combined (P 0.001). Dorsoventral poll displacement was increased by speed (P 0.001) and carpal WD (P = 0.013), craniocaudal poll displacement was increased by speed and WD combined (P 0.001). Pelvic (tubera coxae and sacrum) dorsoventral displacements increased with speed and WD combined (P 0.001). Understanding the effects of speed and WD on limb, back and pelvic kinematics will improve decision making relating to dry and WT exercise within training.

Comment on ‘The immediate effect of water treadmill walking exercise on overground in-hand walking locomotion in the horse’

To the editor We were pleased to see that the latest edition of the Comparative Exercise Physiology (2022; 18(5)) included a study on the topic of water treadmill exercise in horses. The literature in this field is scarce and there is a need to provide more scientific evidence on the use and protocols of water treadmill exercise in horses. We were however disappointed when we read the article entitled ‘The immediate effect of water treadmill walking exercise on overground in-hand walking locomotion in the horse’ by Tranquille et al. published in Comparative Exercise Physiology (2022; 18: 413-418) and wanted to bring some points to the attention of the readers and the authors.

Four Weeks of Incline Water Treadmill Exercise Can Contribute to Increase Epaxial Muscle Profile in Horses.

Water treadmill (WT) exercise is a popular modality for the training and rehabilitation of horses. However, evidence-based literature regarding the use of WT exercise, particularly using inclines, is lacking. The aim of this study was to assess the effect of recurring inclined WT sessions on equine epaxial muscle development. Six horses completed 24 sessions of 15 minutes of WT activity over four weeks. Horses walked with water at the midcannon level at a treadmill incline of 4%. Back traces were measured at three and seven centimetres ventral to the dorsal midline at T5, T9, T14, and T18, prior to the first session (W0) and weekly for 4 weeks (W1-4). Overall, the back traces demonstrated progressive increases in muscle development (p < 0.05), starting at W2 up to W4. At three centimetres ventral to the dorsal midline, the most to least significant increases in gross muscle development were at T18, T5, T9, and T14, respectively, and when measured at seven centimetres ventrally, the most to least significant increases were demonstrated at T5, T18, and T14. It was noted that increases in thoracic back profile musculature were mainly observed within two to four weeks of the WT intervention. It has been concluded that repeated WT exercise on an inclined setting has a significant effect on the rate and size of growth of equine thoracic back profile musculature. Muscle hypertrophy due to resistance training in the WT starts at 2 weeks within the programme, and it progresses as exercise continues to be performed.

Previous Exercise on a Water Treadmill at Different Depths Affects the Accelerometric Pattern Recorded on a Track in Horses.

During a water treadmill (WT) exercise, horses change their accelerometric patterns. We aimed to analyze if these changes persist during terrestrial locomotion. Six horses were randomly subjected to 40 min duration WT exercises, without water (WW), at the depth of fetlock (FET), carpus (CAR) and stifle (STF), with a day off between them. Before and after 30 min after WT, horses were evaluated at walk and at trot on a track with a triaxial accelerometer fixed on the pectoral (PECT) and sacrum (SML) regions. The percent of change from baseline (before WT and after each exercise session) were calculated. Total, dorsoventral, longitudinal and mediolateral accelerometric activities and dorsoventral displacement increased with the accelerometer in PECT but decreased after WT at STF. Velocity increased with the accelerometer in PECT but decreased with the accelerometer in SML, particularly after WT at STF. A reduction in stride frequency was found with the accelerometer in PECT. SL increased with the accelerometer in SML but decreased with WT at STF. Some accelerometric changes that happened on WT remained shortly in terrestrial locomotion. The reduction in some parameters after WT at STF depth seems to indicate fatigue. This should be considered in training or rehabilitation programs for unfit animals.

The immediate effect of water treadmill walking exercise on overground in-hand walking locomotion in the horse

Water treadmill (WT) exercise is frequently used for training/rehabilitation of horses but the effect of WT exercise on short-term movement patterns is yet to be investigated. The objective of this study was to determine the immediate effect of WT exercise on overground limb and back kinematics. Six horses (mean ± standard deviation., age 15±6.5 years, height 164±2 cm and weight 539±37 kg) walked twice in a straight line, led from both sides, before and after a standardised WT exercise session (19 min duration; speed 1.6 m/s; water depths: 0.0/7.5/21.0/32.0/47.0 cm) on a flat concrete surface. Horses wore five inertial-measurement-units to determine poll/wither/pelvic displacement, and 10 anatomical markers to determine fetlock/carpal/tarsal joint angles at specific stride points. Degree of mediolateral tarsal oscillation during stance was graded. Wilcoxon-signed-rank tests were used to investigate differences between pre- and post-WT exercise for each variable. Post-WT exercise, there was a significant decrease in hindlimb fetlock extension at mid-stance compared with pre-WT exercise. No significant changes in movement patterns of the poll/withers/pelvis were detected post-WT exercise. In all horses there was greater mediolateral tarsal oscillation during the stance phase of the stride post-WT exercise, which could relate to muscle fatigue. The results suggest that a 19-min WT session has an effect on immediately-following overground in-hand walking locomotion patterns. Further work is required to determine the duration of this effect, and how different WT speeds and water depths affect locomotion patterns.

Effect of Water Depth on Limb and Back Kinematics in Horses Walking on a Water Treadmill.

Water treadmill (WT) exercise is frequently used for training/rehabilitation of horses. There is limited study into the effect of water depth on limb/back kinematics warranting investigation. The objective was to determine the effect of walking in different water depths, at the same speed, on limb/back kinematics measured simultaneously in a group of horses. Six horses (age:15 ± 6.5 years) completed a standardized WT exercise session (19 minutes duration; speed:1.6 m/s; water depths: 0.0/7.5/21.0/32.0/47.0 cm). Ten waterproof light-emitting-diode tea-light-markers and reflective-spheres were affixed to the skin at predetermined locations; inertial-measurement-units were fixed to the poll/withers/left and right tubera coxae (TC)/sacrum to determine range-of-motion (ROM) changes of these locations. Univariable-mixed-effects-linear-regression-analyses were carried out, with a significance value of P ≤ .05. At maximum carpal/tarsal flexion during swing, regression analyses showed a clear and consistent nonlinear increase in carpal and tarsal flexion at increasing water depths (P < 0.0001 for both variables). As water depth increased there was a significant increase in thoracic spine flexion-extension ROM (P < 0.0001 at all thoracic sites) and increased dorsoventral and mediolateral ROM of the sacrum/left and right TC (P < 0.001 for all variables) as water depth increased. Results suggest that horses responded to an increase in water depth until a threshold depth was reached when the biomechanical response levelled off, and there was increased pelvic roll. In conclusion, changes in limb kinematics brought about by relatively modest increases in water depth at walking speed of 1.6 m/s are sufficient to induce significant changes in back/pelvic movement highlighting key issues with relevance for WT program design.

Evaluation of body surface temperature variations in dogs affected by spinal cord injuries during physiotherapy exercise in a water treadmill

The aim this study was to evaluate variation in body surface temperature (BST) in healthy and spinal cord injured (SCI) dogs, and to outline temperature variation at rest (T0), during (T1) and after (T2) water-treadmill physiotherapy sessions in SCI using infrared thermography (IRT). Sixty-seven dogs of different sex, breed, body weight and age were enrolled: 14 healthy dogs and 53 dogs affected by disc pathologies. The study examined three regions of interest (ROIs): the total image of the spine (IMAGE), the spinal cord area from 1st thoracic vertebra to the last lumbar vertebra (AR01) and the surgery wound or spinal cord lesion area (AR02). Significant BST variations between healthy and SCI were reported in T°max and T°max-min (ΔT) values in IMAGE (P < 0.05). In SCI group, AR01 and AR02 assessment showed an increase in temperature ate the sited of the injured area and adjacent body structures. In SCI, a significant effect of water-treadmill exercise in AR01 and AR02 was reported. In fact, both AR01 and AR02 reported higher BST (T°max, T°mean, T°min and ΔT) during the physical exercise (T1), representing the response to physical activity of the spine vascularization, muscles and column contiguous tissues. Furthermore, in T2, the same areas reported a significant lower BST (T°max, T°mean, and ΔT), related to a decrease in tissue inflammation on the target area of the water treadmill physiotherapy. This study highlights how IRT can detect BST variations associated with injured areas. In addition, IRT revealed a positive effect of water-treadmill exercise on the injured spinal cord areas, thus it could be a viable non-invasive and rapid method to support both clinical examination and assessment of the effectiveness of medical treatment in SCI.

Physiological effects of land and water treadmill exercise in dogs

ABSTRACT: The application of hydrotherapy is growing in the field of animal rehabilitation to improve strength, endurance, fitness, and range of motion, in addition to reducing pain. In the same way, land-based activity is recommended for various conditions, including hypertension, muscle atrophy, and obesity. There is a lack of studies that evaluate the safety of incremental exercise in American Pit Bull Terriers. This study assessed the influence of activity on underwater and dry land treadmills on the physiological parameters of dogs. In this regard, 12 adult, male, healthy, and untrained American Pit Bull Terriers were subjected to an incremental exercise test (IET) on the underwater treadmill (Group I) and the dry land treadmill (Group II). Heart rate (HR), respiratory rate (RR), rectal temperature (RT), systolic blood pressure (SBP), and electrocardiographic evaluation, were evaluated before activity (T0), immediately after (T1), 30 min after (T2), and 90 min after the end of exercise (T3), and plasmatic lactate concentrations were measured at T0, T1, and T2 time points. Results obtained were submitted to the Shapiro-Wilk test, ANOVA and Tukey’s test, considering P&lt;0.05. Water activity induced a reduction in RR (P=0.00674) in all examinations after the test on the underwater treadmill and proved to be more demanding than activity on the land treadmill, considering the presence of a deeper and slower RR. Exercise sessions in both groups did not elevate the lactate concentration. The IET can be performed safely on an underwater or dry land treadmill in healthy American Pit Bulls.

A comparison of stride parameters and carpal and tarsal joint angles during terrestrial and swimming locomotion in domestic dogs

In recent years, canine hydrotherapy has become increasingly popular to treat a range of conditions despite a lack of empirical evidence. It is currently unclear whether joint angles and limb movements performed by dogs during swimming are quantifiably beneficial for healthy animals. This study investigated the swimming kinematics of healthy dogs to establish baseline data for this activity and compare limb kinematics to that of overground locomotion. Kinematic data were recorded from eight healthy dolichocephalic dogs (mean age: 3.4±2.2) of a variety of breeds. Overground data were collected prior to swimming and consisted of dogs trotting on a flat surface. Swimming data were collected using an underwater camera during a standard hydrotherapy session conducted by a trained canine hydrotherapist. Range of motion, primarily due to an increase in flexion, was significantly greater (P&lt;0.005) during swimming than trotting. Stride length (P&lt;0.001) and frequency (P&lt;0.005) were both significantly reduced in swimming compared to trot. Swimming kinematics recorded in this study are consistent with previously published data on canine aquatic locomotion but differ from those previously reported for water treadmill exercise. This study provides an insight into aquatic locomotion in healthy dogs indicating that range of motion exceeds that of terrestrial gaits. It is unclear whether these changes are beneficial for healthy animals and therefore further research is required to develop evidence-based protocols for industry practice.

The Effect of Water Treadmill Exercise on Children with Attention Deficit Hyperactivity Disorder

Background Attention deficit hyperactivity disorder (ADHD) is one of the prevalent disorders in child psychiatry with the potential of damage to mental talent evolution process and socio-emotional skills. This study aimed to determine the effect of Water treadmill exercise on children with Attention deficit hyperactivity disorder (ADHD). Materials and Methods: This was an experimental study with pretest, posttest design which was done in Gorgan. Participants were 46 children (mean age = 9.45 ±0.5, male = gender) who were identified and selected based on diagnostic criteria in two stages and were randomly divided into experimental and control groups (n=23). The experimental group performed running on a Water treadmill for eight weeks with three sessions each week (24 sessions in total) and each session for 30 minutes. The exercise intensity was for 10 minutes 40-45% and 20 minutes 55-65% of the maximum heart rate reserve. All sessions begin with a brief warm-up, including light aerobic activity and dynamic, static stretching, and end with a cool-down. Disorder Levels were measured using the Conners’ Parent Rating Scale-Revised (CPRS-R), and diagnostic interviews. Data were analyzed using SPSS software version 22. Results: The results showed that after controlling the pretest levels, behavior problems, social problems, anxiety-shyness, psychosomatic, and the overall score of attention deficit hyperactivity disorder in the experimental group were significantly lower the posttest than the control group (p <0.05). Conclusion Based on the results, exercise interventions with Water treadmill for eight weeks effectively reduce the symptoms of attention deficit hyperactivity disorder in children and can be used as an appropriate intervention.

Consensus for the General Use of Equine Water Treadmills for Healthy Horses.

Simple SummaryWater treadmill exercise has become popular in recent years for the training and rehabilitation of equine athletes. Water treadmill exercise sessions can be tailored to the individual horse and the training/rehabilitation goals by altering the frequency, duration of exercise, water depth and belt speed. Recent work suggests that there are large variations in current modes of use between users, despite shared training or rehabilitation goals. In 2019, a group of researchers and experienced water treadmill users met in the UK to establish what was commonly considered to be best practice in the use of the modality. The result of these discussions was the production of ‘Water treadmill guidelines—a guide for users’, released in 2020 via various equestrian websites. The purpose of this article is to describe the development of these guidelines and propose them as a starting point for further collaboration between researchers and practitioners in the pursuit of ‘best practice’ in water treadmill exercise for horses.Water treadmill exercise has become popular in recent years for the training and rehabilitation of equine athletes. In 2019, an equine hydrotherapy working group was formed to establish what was commonly considered to be best practice in the use of the modality. This article describes the process by which general guidelines for the application of water treadmill exercise in training and rehabilitation programmes were produced by the working group. The guidelines describe the consensus reached to date on (1) the potential benefits of water treadmill exercise, (2) general good practice in water treadmill exercise, (3) introduction of horses to the exercise, (4) factors influencing selection of belt speed, water depth and duration of exercise, and (5) monitoring movement on the water treadmill. The long-term goal is to reach a consensus on the optimal use of the modality within a training or rehabilitation programme. Collaboration between clinicians, researchers and experienced users is needed to develop research programmes and further guidelines regarding the most appropriate application of the modality for specific veterinary conditions.

Water height modifies forelimb kinematics of horses during water treadmill exercise

Although equine water treadmills (WTs) are increasingly being used for the rehabilitation of equine athletes, the immediate- and short-term effects of this type of exercise on limb movement in the WT and overground are unknown. Therefore, the objective of this study was to evaluate the effects of WT exercise on equine forelimb kinematics on land and under various WT conditions before and after a prolonged period of WT conditioning. External markers were used to collect 2D kinematic data (joint extension, flexion, range of motion (ROM), elevation; stride mechanics) at 120 frames/s. Thirteen mixed breed, English performance horses were filmed under three test conditions: (1) horses walked on sand; (2) horses walked on a WT (water heights: dry, carpus, stifle); (3) horses walked on sand immediately following a WT session. Walking speeds during testing varied between horses, ranging from 1.3-1.5 m/s, but were held constant for each individual horse for all tests on both days. Testing occurred on days 1 and 10, with horses being trained on the WT for days 2 through 8 (28 min/day). Comparisons were made using linear mixed effects models. Carpal ROM and elbow ROM were greater when horses were walked in water, compared to without water (dry treadmill) and overground (P&lt;0.0001 for all). This increased ROM was achieved primarily via an increase in joint flexion. With the addition of water, stride length increased and stride frequency decreased, accompanied by an increased percentage duration of swing phase. No effects of conditioning on gait mechanics were observed overground. Therefore, WT exercise may be meaningful for physical rehabilitation through increased joint flexion and ROM observed.

Change in muscle development of horses undergoing 20 weeks of water treadmill exercise compared with control horses

Change in muscle development of horses undergoing 20 weeks of water treadmill exercise compared with control horses

Water treadmill exercise reduces equine limb segmental accelerations and increases shock attenuation

BackgroundEquine water treadmills (WTs) are growing in popularity because they are believed to allow for high resistance, low impact exercise. However, little is known about the effect of water height on limb loading. The aim of this study was to evaluate the effect of water height and speed on segmental acceleration and impact attenuation during WT exercise in horses. Three uniaxial accelerometers (sampling rate: 2500 Hz) were secured on the left forelimb (hoof, mid-cannon, mid-radius). Horses walked at two speeds (S1: 0.83 m/s, S2: 1.39 m/s) and three water heights (mid-cannon, carpus, stifle), with a dry WT control. Peak acceleration of each segment was averaged over five strides, attenuation was calculated, and stride frequency was estimated by the time between successive hoof contacts. Linear mixed effects models were used to examine the effects of water height, speed, and accelerometer location on peak acceleration, attenuation and stride frequency (p < 0.05).ResultsPeak acceleration at all locations was lower with water of any height compared to the dry control (p < 0.0001). Acceleration was reduced with water at the height of the stifle compared to mid-cannon water height (p = 0.02). Water at the height of the stifle attenuated more impact than water at the height of the cannon (p = 0.0001).ConclusionsWater immersion during treadmill exercise reduced segmental accelerations and increased attenuation in horses. WT exercise may be beneficial in the rehabilitation of lower limb injuries in horses.

Water depth modifies back kinematics of horses during water treadmill exercise.

Water treadmill exercise can be incorporated into the rehabilitation programmes of horses recovering from back pathology, yet little is known about the effect of this type of exercise on thoracolumbar movement ranges. To measure the flexion-extension range of motion (FE ROM) of the thoracolumbar spine and pelvic vertical displacement during water treadmill walking at 3 water depths and compare these with the control condition. Within-subject trial using a crossover design in healthy horses. A total of 14 horses walked at 0.8 m/s on a water treadmill for 3 min at each of the following depths; hoof (control), metatarsophalangeal joint (low), tarsal joint (medium) and femoropatellar joint (high). Skin surface markers on T6, T10, T13, T18, L3, L5 and S3 were used to obtain FE ROM and the minimum and maximum angular motion pattern values (AMPmin and AMPmax) for T10, T13, T18, L3 and L5. Markers placed on left and right tuber coxae were used to obtain pelvic vertical displacement. Friedman's tests and post hoc Wilcoxon's signed ranks tests were used to determine the effects of water depth on measured variables. The FE ROM of T10 (8.4°), T13 (8.1°), T18 (6.9°) and L3 (6.4°) when walking at high depth was significantly greater than control (5.5, 5.7, 5.1 and 5.1°, respectively; P<0.008); T13 AMPmin was significantly lower in high water (-3.0°) than control (0.1°, P = 0.001) and L3 AMPmax significantly greater in high water (-1.9°) than control (-4.8°, P = 0.001). There was no significant association between pelvic vertical displacement and water depth. Walking in high water causes cranial thoracic extension and thoracolumbar flexion when compared with walking in water at hoof depth. This postural change should be considered when designing rehabilitation programmes for horses with back and/or hindlimb pathology.

Heart rate response during underwater treadmill training in adults with incomplete spinal cord injury.

Walking on a submerged treadmill can improve mobility in persons displaying lower limb muscle weakness and balance deficits. Little is known, however, regarding the effect of water treadmill exercise on cardiac performance in persons with incomplete spinal cord injury (iSCI). To assess heart rate response during underwater treadmill training (UTT) in adults with iSCI. Seven males and 4 females with iSCI (age = 48 ± 13 years; 5 ± 8 years after injury) completed 8 weeks of UTT (3 sessions per week; 3 walks per session) incorporating individually determined walking speeds, personalized levels of body weight unloading, and gradual, alternating increases in speed and duration. Heart rate was monitored during the last 15 seconds of the final 2 minutes of each walk. Over the course of 3 biweekly periods in which walking speed remained constant, heart rate fell by 7% (7 ± 1 b•min(-1); P < .001) in weeks 2 and 3, 14% (17 ± 6 b•min(-1); P < .001) in weeks 4 and 5, and 17% (21 ± 11 b•min(-1); P < .001) in weeks 6 and 7. In adults with iSCI, progressively greater absolute and relative reductions in submaximal exercise heart rate occurred after 2 months of UTT featuring a systematic increase in training volume.

Monitoring changes in skin temperature associated with exercise in horses on a water treadmill by use of infrared thermography

Infrared thermography (IRT) was used to assess surface temperature change as an indirect measure of muscle activity and exercise associated changes in blood flow in the working hind limb muscles of horses (n=7) undergoing water treadmill exercise. Three treatments were investigated including the treadmill ran dry (TD), water at the height of the proximal interphalangeal joint (PIP) and water at the height of the carpus (CP). Maximum skin surface temperature was recorded from the region of the semitendinosus muscle during exercise at each water height. There was a significant difference in surface hind limb temperature between exercise on the water treadmill ran dry and with water at the height of the PIP and CP (P<0.0001) with hotter temperatures recorded during the TD treatment. There was a greater increase in surface temperature of the hind limbs from pre exercise to maximum temperature during the PIP and CP treatments when compared to the TD treatment, however, this was not significant (P=0.58). There was no significant difference in surface hind limb temperature found between exercise in water at the height of the PIP and water at the height of the CP. The findings from this study suggest that IRT is able to non-invasively detect muscle activity and associated changes in blood flow whilst horses are exercised on a water treadmill. IRT could potentially be used as an alternative method to assess muscle activity and temperature change in an aquatic environment where existing methods present methodological challenges.

Biomechanical responses of the back of riding horses to water treadmill exercise

There is a lack of evidence for the presumed beneficial effects of water treadmills on the movement of the horse’s back. The aim of the study was to evaluate the effects of water treadmill exercise on axial rotation (AR), lateral bending (LB) and pelvic flexion (PF) in horses. The back kinematics of a group of riding horses were studied at the walk in a water treadmill at different depths of water (hoof, fetlock, carpus, elbow and shoulder joint levels) over a period of 10days. Skin markers were placed at anatomical locations on the back. AR, LB and PF were measured on days 1 and 10 using two high-speed video cameras. There was a significant increase in AR compared to baseline at the level of the carpus and at higher water levels, whereas LB was significantly lower than baseline values at water levels that reached the elbow and shoulder joints. PF was significantly higher than baseline values at each water depth other than hoof water depth. At increasing water depths, there were significant increases in flexion and rotation of the back. At the highest water levels, there was reduced bending of the back. After 10days, horses exhibited more bending of the back.

The effect of water height on stride frequency, stride length and heart rate during water treadmill exercise

Water treadmill exercise is often incorporated into rehabilitation programmes for horses yet little is known about the biomechanical and physiological responses to water walking. To establish whether stride frequency (SF) reached steady state as a result of 6 introductory water treadmill sessions and then to investigate the effect of increasing water height on SF, stride length (SL) and heart rate (HR). Nine horses with no previous experience of water treadmills completed 6 sessions of walking for between 15 and 30 min. Each horse was fitted with a leg mounted accelerometer to measure SF. The effect of session on SF was tested using univariate ANOVA. Eight horses completed 3 further sessions at each of the following water heights; proximal interphalangeal joint (PIP), carpus and ulna. SF, SL and HR at each water height were compared to a control (hoof height) using univariate ANOVA. When SF during introductory sessions 4-6 were compared, there was no significant effect of session on SF (P > 0.05). In the second part of the experiment, SF was 0.57 ± 0.03 strides/s at control, 0.54 ± 0.03 strides/s at the PIP joint, 0.51 ± 0.02 strides/s at the carpus and 0.52 ± 0.03 strides/s at the ulna. Stride frequency at carpal and ulna height was significantly lower than at control (P < 0.05). Stride length was 1.53 ± 0.09 m for control, 1.63 ± 0.10 m at the PIP joint, 1.71 ± 0.08 m at the carpus and 1.68 ± 0.10 m at the ulna. Stride length at carpal and ulna height was significantly greater than control (P < 0.05). There was no significant difference between HR during control and any other water height (P > 0.05). Horses reached steady state gait within the first 6 sessions of water treadmill exercise. Walking in water at the level of the carpus or ulna resulted in a lower SF compared to walking in water at hoof height.