Colic after swimming exercise in racehorses: an investigation of incidence, management, surgical findings and outcome

Workload and spirometry associated with untethered swimming in horses

BACKGROUND

Swimming has been used empirically for rehabilitation and conditioning of horses. However, due to challenges imposed by recording physiological parameters in water, the intensity of free swimming effort is unknown.

OBJECTIVES

Measure the physiological workload associated with untethered swimming in horses. Five fit Arabian endurance horses were assessed while swimming in a 100 m-long indoor pool. Horses were equipped with a modified ergospirometry facemask to measure oxygen consumption (V̇O2) and ventilatory parameters (inspired/expired volumes, VI, VE; peak inspiratory/expiratory flows, PkVI, PkVE; respiratory frequency, Rf; minute ventilation, VE; inspiratory/expiratory durations and ratios, tI, tE, tI/ttot, tE/ttot); and an underwater electrocardiogram that recorded heart rate (HR). Postexercise venous blood lactate and ammonia concentrations were measured. Data are reported as median (interquartile ranges).

RESULTS

Horses showed bradypnea (12 breaths/min (10-16)) for the first 30 s of swimming. V̇O2 during swimming was 43.2 ml/(kg.min) (36.0-56.6). Ventilatory parameters were: VI = 16.7 L (15.3-21.8), VE = 14.7 L (12.4-18.9), PkVI = 47.8 L/s (45.8-56.5), PkVE = 55.8 L/s (38.3-72.5), Rf = 31.4 breaths/min (20.0-33.8), VE = 522.9 L/min (414.7-580.0), tI = 0.5 s (0.5-0.6), tE = 1.2 s (1.1-1.6), tI/ttot = 0.3 (0.2-0.4), tE/ttot = 0.7 (0.6-0.8). Expiratory flow tracings showed marked oscillations that coincided with a vibrating expiratory sound. HR was 178.0 bpm (148.5-182.0), lactate = 1.5 mmol/L (1.0-1.9) and ammonia = 41.0 µmol/L (36.5-43.5).

CONCLUSIONS

Free (untethered) swimming represents a submaximal, primarily aerobic exercise in horses. The breathing pattern during swimming is unique, with a relatively longer apneic period at the beginning of the exercise and an inspiratory time less than half that of expiration.

Resveratrol attenuated high intensity exercise training-induced inflammation and ferroptosis via Nrf2/FTH1/GPX4 pathway in intestine of mice

BACKGROUND

Moderate exercise has beneficial effects for human health and is helpful for the protection against several diseases. However, high intensity exercise training caused gastrointestinal syndrome. Resveratrol, a plant extract, plays a vital role in protecting various organs. However, whether resveratrol protected mice against high intensity exercise training-induced intestinal damage remains unclear. In this study, our objective was to investigate the protective effects and mechanism of resveratrol in high intensity exercise training-treated mice.

METHODS

Mice were treated with swimming exercise protocol and/or resveratrol (15 mg/kg/day) for 28 consecutive days. Then, the mice were sacrificed, and a series of evaluation indicators, including inflammatory factors and intestinal permeability of the gut, were measured based on this model. The expressions of inflammatory factors (tumor necrosis factor (TNF)-α; interferon (IFN)-γ, interleukin (IL)-6 and IL-10), oxidative stress (Nrf2, glutathione (GSH), hydrogen peroxide (H2 O2), catalase (CAT) and malondialdehyde(MDA)), intestinal barrier (gut permeability, ZO-1, Occludin and Claudin-1 as well as ferroptosis (Fe2+, Fe3+, SLC7A11, glutathioneperoxidase 4 (GPX4) and ferritin heavy chain 1 (FTH1)) were measured, respectively.

RESULTS

High intensity exercise training induced colon damage, manifested as inflammation (increased TNF-α, IFN-γ and IL-6 concentrations, and decreased IL-10 concentration), oxidative stress (the increase of H2O2 and MDA concentration, and the reduced CAT and GSH activities), intestinal barrier injury (increased gut permeability and intestinal fatty-acid binding protein concentration,and inhibited ZO-1, Occludin and Claudin-1 expressions) and ferroptosis (the increased of Fe2+ and Fe3+ concentrations, and suppressed phosphorylated Nrf2, SLC7A11, GPX4 and FTH1), which was relieved by resveratrol treatment in mice.

DISCUSSION

Resveratrol attenuated high intensity exercise training-induced inflammation and ferroptosis through activating Nrf2/ FTH1/GPX4 pathway in mouse colon, which providing new ideas for the prevention and treatment of occupational disease in athlete.

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.