Many horse owners and horse trainers are facing the question of how to minimize the risk of exertional rhabdomyolysis. Besides a well-designed conditioning exercise programme, particular attention should be paid to dietary factors, such as a well-balanced diet, sufficient electrolytes, and natural antioxidants aimed at reducing exercise-induced muscle damage.

Joerg Schnackenberg
Marketing Manager Asia-Pacific Oceania
AstaReal

An exercising horse demands an adequate intake of optimal nutrition to maintain its muscle strength and endurance. During exercise, oxygen consumption increases significantly to maintain the energy demands of skeletal muscles. The increased oxygen consumption is accompanied by the release of reactive oxygen molecules that can lead to oxidative damage of skeletal muscle tissue, an effect that is further aggravated by the release of additional reactive oxygen species by immune cells involved in repairing damaged muscle tissue post-exercise1. Increases in serum creatine kinase activity is a reliable indicator for exercise-induced muscle necrosis, also known as exertional rhabdomyolysis (ER) or “tying up syndrome”2,3.

How to avoid tying up?

ER is probably the most common muscle disorder found in horses and its onset may be caused by multiple factors, including overexertion, dietary issues (high grain diet, electrolyte imbalance) or genetic predisposition4,5.

Many horse owners and horse trainers are facing the question of how to minimize the risk of exertional rhabdomyolysis. Besides a well-designed conditioning exercise programme, particular attention should be paid to dietary factors, such as a well-balanced diet, sufficient electrolytes, and natural antioxidants aimed at reducing exercise-induced muscle damage. The antioxidant status in a horse plays an important role6 and dietary supplementation with natural antioxidants will enhance the horse’s antioxidant status, and minimise the risk of muscle injuries caused by oxidative stress. The vitamins C and E are widely used as feed supplements to improve the horse’s antioxidant status7.

Natural astaxanthin – the antioxidant of choice

In recent years, another natural antioxidant, astaxanthin, has received a lot of attention because of its superior antioxidant qualities, lack of pro-oxidant capabilities and unique cellular mechanism to protect cells and mitochondria – the powerhouses of the cell – from oxidative stress and damage8,9,10.

Astaxanthin is a carotenoid most commonly found in marine animals such as shrimp, lobster or salmon (astaxanthin makes the salmon flesh pink), but also in birds such as flamingos. The organism that really is at the beginning of the food chain is a tiny microalga called Haematococcus pluvialis. It produces large amounts of astaxanthin as a protective measure against environmental conditions – for example, draughts or strong sun exposure – that trigger production of reactive oxygen molecules. When the algae are consumed by animals such as shrimp or salmon, the protective effects of astaxanthin are transferred to the next level in the food chain.

Protecting the cell’s mitochondria

Because astaxanthin can integrate into the entire thickness of the cellular and mitochondrial membrane bilayer, its antioxidant powers can protect against aggressive oxygen molecules from both inside and outside the membrane boundary – unlike other antioxidants that work only inside or outside of a cell or mitochondria11.

Emerging clinical research is continuously providing further strong evidence of the benefits of natural astaxanthin’s antioxidant and anti-inflammatory properties. Numerous studies have demonstrated that daily supplementation with natural astaxanthin provides a wide range of health benefits in humans, including muscle strength and endurance12.

Astaxanthin supplementation reduces tying up episodes

More than 20 years ago, AstaReal conducted the first trial with horses experiencing frequent tying up episodes, and found that supplementation with AstaReal® natural astaxanthin for 2-3 weeks alleviated the syndrome; when supplementation was stopped, the tying up episodes returned after 2 weeks. Recent studies with AstaReal® natural astaxanthin added further evidence, showing the benefits natural astaxanthin can have for horses. One study with thoroughbred race horses clearly showed that natural astaxanthin protected the muscles from exercise-induced damage. Blood serum analysis from 24 thoroughbred horses revealed that the antioxidant capability of natural astaxanthin prevented the accumulation of serum creatine kinase activity, an indicator of muscle damage, in a dose-dependent manner13. This study built on earlier trials that suggested that dietary interventions and a wide variety of antioxidant supplements should be recommended for the management of horses with exercise-induced muscle damage14,15,16. However, despite numerous studies testing different antioxidants, no effective supplementation strategy for the prevention of exercise-induced muscle damage had been established so far.

Natural astaxanthin and L-carnitine act as mitochondrial nutrients

We know that the key to a horse’s strength and endurance is efficient and continuous energy production by the cells’ mitochondria. We already know that astaxanthin is protecting the mitochondrial membrane, but that alone isn’t making the horse stronger or faster. Mitochondrial function together with the flow of nutrients, like sugar and fat, into mitochondria are determinants of energy production and endurance. Extensive research in animals has shown that astaxanthin enhances the transport of nutrients across the mitochondrial membrane by protecting nutrient-carrying transporters (CPT-1) from damage by reactive oxygen species, ensuring a constant and efficient energy supply17. The transporter, CPT-1, needs L-carnitine to efficiently transport fatty acids across the mitochondrial membrane where they can be metabolized into energy18,19. Therefore, it makes sense to combine astaxanthin and L-carnitine to optimise mitochondrial energy production in muscles. Trials with thoroughbred race horses showed improved protection from muscle damage and enhanced energy conversion when both nutrients were provided in the horses’ daily diet20. Horses that received a combination of astaxanthin and L-carnitine showed significantly reduced creatine kinase activity and lower levels of another marker of acute or chronic muscle damage, lactate dehydrogenase.

Natural astaxanthin accelerates the healing process of damaged muscle tissue

Horses experiencing muscle damage from tying up or exertional rhabdomyolysis will recover after rest and dietary intervention within a few weeks. However, the repair of damaged muscle tissue can lead to scarring that may affect the horse’s strength and endurance in the long run. Two genes are essential for the muscle repair process: the gene Col1A1 carries the blueprint for the synthesis of the fibrillary collagen type 1 and bFGF encodes an important growth factor (“basic Fibroblast Growth Factor).

Animal studies have shown that astaxanthin upregulated the expression of these two genes, increased the deposition of hyaluronic acid, reduced tissue scarring and accelerated the healing process21,22,23.

These ground-breaking studies offer a dietary solution to keep a horse healthy, while improving its performance.

Do you have questions?
Please contact us for sources, references or with any questions you
may have about astaxanthin and its health benefits for horses.
nutra@fujichemical.co.jp

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