Changes in skeletal muscle composition in response to swimming training for young horses

Kinematic Analysis During Straight Line Free Swimming in Horses: Part 2 - Hindlimbs

Background

Swimming is used for rehabilitation and conditioning purposes in equine sports medicine. We described the swimming kinematics of the equine forelimbs in Part 1. The aim of Part 2 is to assess stifle, tarsus, and hind fetlock joints kinematics in swimming horses. The objectives were 1- to calculate and compare joint angles during swimming against passive mobilizations (PM), 2- to determine joints angular velocities during a swimming stride cycle.

Methods

Eleven elite endurance horses were used to swim in a 100-meter straight pool. Underwater (swimming) and overground PM videos were recorded from the horses' left side. Joint markers were applied on the lateral hoof wall, lateral metatarsal epicondyle, lateral aspect of the talus, lateral femoral epicondyle, and great trochanter of the femur. As a reference, maximal fetlock, tarsus, and stifle flexion/extension angles were determined during PM overground. Differences between angle extrema, angular velocities, and range of motion (ROM) were statistically compared.

Results

The tarsus ROM was similar during PM and swimming. The stifle and fetlock ROM were greater during PM, although the stifle flexion was greater during swimming. The stifle and tarsus had the greatest hindlimb angular velocity during the swimming cycle. Greater angular velocities were observed during the retraction phase for all the hindlimb joints.

Conclusion

A short retraction phase with great angular velocity for the joints of interest characterized the swimming pattern observed. Swimming may be beneficial in horses when an increased ROM of the tarsus and stifle or a reduced fetlock extension is indicated for rehabilitation purposes.

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.

Track Surfaces Used for Ridden Workouts and Alternatives to Ridden Exercise for Thoroughbred Horses in Race Training

Little is known about the types of surfaces used during training of Thoroughbred racehorses or methods of exercise used in addition to ridden track-work. Our aims were to (1) describe the types of surfaces used in the training of Thoroughbred racehorses and to (2) identify alternative approaches used to exercise horses in addition to, or in place of, ridden overground track-work. Information regarding surface and alternative exercise methods was collected as part of an in-person survey of training practices of 66 registered Thoroughbred trainers in Victoria, Australia. Sand and synthetic surfaces were used by 97% and 36% of trainers respectively for slow-workouts, with galloping on turf training tracks used in training regimens by 82% and synthetic by 58% of trainers. Of those trainers utilising turf tracks, only 34% of gallop training was completed on turf despite turf being the predominant racing surface. Almost 90% of trainers used alternatives to ridden exercise. There is substantial variation in training surface used and alternative types of exercise undertaken by Victorian trainers. Future research should focus on how such practices relate to injury risk, particularly as it relates to the importance of musculoskeletal adaptation to specific race-day surfaces.

Principles and Application of Hydrotherapy for Equine Athletes

Hydrotherapy has become a key element within equine rehabilitation protocols and is used to address range of motion, proprioception, strength, neuromotor control, pain, and inflammation. Various forms of hydrotherapy can be tailored to the individual's injury and the expected return to athletic performance. This article describes the mechanisms of action of hydrotherapies and potential use in the clinical management of equine musculoskeletal injuries.

Highly athletic terrestrial mammals: horses and dogs

Evolutionary forces drive beneficial adaptations in response to a complex array of environmental conditions. In contrast, over several millennia, humans have been so enamored by the running/athletic prowess of horses and dogs that they have sculpted their anatomy and physiology based solely upon running speed. Thus, through hundreds of generations, those structural and functional traits crucial for running fast have been optimized. Central among these traits is the capacity to uptake, transport and utilize oxygen at spectacular rates. Moreover, the coupling of the key systems--pulmonary-cardiovascular-muscular is so exquisitely tuned in horses and dogs that oxygen uptake response kinetics evidence little inertia as the animal transitions from rest to exercise. These fast oxygen uptake kinetics minimize Intramyocyte perturbations that can limit exercise tolerance. For the physiologist, study of horses and dogs allows investigation not only of a broader range of oxidative function than available in humans, but explores the very limits of mammalian biological adaptability. Specifically, the unparalleled equine cardiovascular and muscular systems can transport and utilize more oxygen than the lungs can supply. Two consequences of this situation, particularly in the horse, are profound exercise-induced arterial hypoxemia and hypercapnia as well as structural failure of the delicate blood-gas barrier causing pulmonary hemorrhage and, in the extreme, overt epistaxis. This chapter compares and contrasts horses and dogs with humans with respect to the structural and functional features that enable these extraordinary mammals to support their prodigious oxidative and therefore athletic capabilities.

Physiological changes in jeju crossbred riding horses by swim training

The changes in physiologic parameters by swim exercise duration were examined in five female well-trained Jeju crossbred riding horses that had riding experience of more than three years without swim training experience. The horses were performed with swim exercise for 10 min (60.0 m/min) once a day for 14 days. Physiologic characteristics and haematic parameters were measured before swimming, immediately after swimming, and after a 10 min rest at first day (D0), 7 days (D7), and 14 days (D14) of training. After 14 days of swim training, heart rate (p<0.05), blood glucose (p<0.05), lactate concentration (p<0.001), packed cell volume (p<0.01), and hemoglobin (p<0.01) measured immediately after swim and after 10 min rest showed significant lower values than those of D0. The results illustrate the benefits of swim training for riding horses and the need for the establishment of swimming routines of appropriate duration and intensity to maximize the advantages of swim training.

A scientific background for skeletal muscle conditioning in equine practice

The main goal of any conditioning programme in athletic horses is to improve performance by inducing physiological changes within the animal's body. Equine skeletal muscles have a considerable potential to adapt during training and these adaptations have important physiological implications that influence stamina, strength and speed. Although there is an extensive specialized literature in this regard, scientific based muscle conditioning methods have not been introduced sufficiently in the equine sport practice. After a brief synopsis of both equine muscle exercise physiology and muscular adaptations to training, including their physiological significance, this review focuses on specific training programmes that induce muscular adaptations in athletic horses. The article addresses the following principal question: what kind of stimuli for what kind of muscular adaptations? The experimental data are discussed separately for racehorses (thoroughbreds, trotters and endurance horses) and sport horses (dressage, show jumpers and carriage). Finally, published results about the influence of relevant training parameters (such as intensity, duration and type of exercise) on muscular responses are discussed, as well as those concerning overtraining and detraining. The article closes with some concluding remarks on importance of their application in practice.

Efeito da natação associado a diferentes dietas sobre o músculo tibial anterior do rato: estudo morfológico e histoquímico

O objetivo deste estudo foi investigar o efeito da associação de diferentes freqüências de programas de natação e dietas nas características do músculo tibial anterior. Foram utilizados 24 ratos machos Wistar. Estes foram aleatoriamente divididos em três grupos: não treinados (controle), grupo treinado (2x/sem) e grupo treinado (5x/sem). Cada grupo foi dividido em dois grupos, os quais receberam uma das dietas: normal ou hipercalórica. Depois do período de treinamento, amostras do músculo foram coletadas e congeladas a -70ºC. Cortes histológicos (8µm) obtidos em um micrótomo criostato (-20º) foram submetidos aos métodos HE e NADH-TR, m-ATPase (pH 4,4) e Sudan Black. A morfologia e o grau de hipertrofia foram avaliados usando o método do menor diâmetro. Os dados foram submetidos ao teste de variância (ANOVA-one way). As fibras musculares foram classificadas como SO, FOG e FG, apresentando um padrão de distribuição em mosaico em todos os grupos. As fibras musculares revelaram leve hipertrofia em todos os grupos. Os pesos inicial e final foram significativamente diferentes nos grupos treinados. Nos grupos treinados, especialmente no grupo de 5x/sem, as fibras musculares revelaram hipertrofia e splitting com alguns mionúcleos internos. Algumas fibras revelaram-se atrofiadas e esta observação sugeriu desnervação. O metabolismo oxidativo foi mais intenso nas fibras SO e FOG; não houve alterações na habilidade contrátil do músculo e o teor de lipídios foi intenso nas fibras SO, moderado nas FOG e fraco nas FG. O presente estudo, com este protocolo, treinamento de 2x/sem e 5x/sem, causou diferentes tipos de lesões morfológicas nas fibras. A dieta hipercalórica não causou resultados estatisticamente significantes em comparação com a dieta normal.

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.