In a study of Thoroughbreds done last year, it was discovered that supplementing horses with Co-enzyme Q10 (CoQ10) increased the activity of slow-twitch muscles.

CoQ10 is an antioxidant that horses produce naturally, though at much lower concentrations as compared to humans and several other species. CoQ10 has a fundamental role in the cellular process and is essential for the production of biological/chemical energy.

Sprinters vs. Stayers

Recent work into the world of genetics has revealed marked variation with the Myostatin (MSTN) gene. This gene regulates muscle mass both by limiting the number and size of muscle cells/fibres. In fact, you’ve probably already heard of this gene for its effects creating the “double muscle Belgian Blue cattle breed.” As it turns out, two areas of variation of this gene in horses may play a role in horses being considered “sprinters” or “stayers.”

Using muscle biopsy techniques, researches have revealed different muscle fibre types that have different capacities for contractile speed, and energy metabolism. It is these different fibres that are responsible for making Quarter Horses adept at sprinting, Thoroughbreds able to run upwards of 2 miles, and Arabians able to cover 100 miles in a day.

Horses have three types of muscle fibres:

Type I – These are the “slow-twitch” type, that are more capable of aerobic, sustained contraction thanks to their high number of mitrochondria (for oxidative metabolism) and capillaries (for oxygen delivery).

Type IIX – These are the “fast twitch” type, that use glycogen/glucose preferentially for energy production, with fewer mitochondria and capillaries.

Type IIA – There are the “fast-twich” fibres which are intermediate in their metabolism type but have high amounts of mitochondria.

It is well established that Quarter Horses tend to have more Type IIX fibres, while Arabians tend to have more Type I fibres. Fibre type percentages also vary across different muscles of an animal, with more core or standing muscle groups having higher slow-twich (non-fatiguing) fibres and while the more power-generating muscle groups have more fast-twitch fibres (this is what actually generates dark meat vs. white meat in your Thanksgiving turkeys).

Being able to map the horse’s entire genome (all of its genetic material) has allowed researchers to identify genes that may play a role in performance, with more sensitivity than gross dissection of a muscle biopsy. The research has revealed that the MSTN gene shows two areas of variation that appear to affect racing performance and abilities. In a nutshell, these two areas are as follows:

  1. Single nucleotide polymorphism (SNP) where the base component of a small section of the double helix structure of DNA may be a “C” or “T”
    – Accordingly, a horse, with two copies of every gene, one from its dam and one from its sire, could have the genotype: CC, CT or TT
    – C is considered the sprint variant, so horses with CC tend to be better sprinters, while horses with TT are best suited for longer distances.
    – Horses with CC also tend to have higher muscle mass. As such, Quarter Horses tend to have more CC genotypes within their breed.
  2. Short Interspersed Nuclear Element (SINE) insertion
    – Horses either have the insertion (I) or don’t (N) so a horse could have the genotype: II, IN, NN
    – The insertion appears to be linked to the C copy of the gene and, if it’s present, horses tend to have more IIX (fast twitch) muscle types.

In one study of 81 Thoroughbreds (Rooney et al., 2017), it was found that 45% of the horses had CC/II, 42% had CT/IN and 13% had TT/NN. The authors found that CC/II horses had lower mitochondrial content and lower proportions of type I fibres, and the most IIX type of fibres, adding support to the sprint/short distance suitability of these horses.

The study further investigated differences in the electron transport chain components of the mitochondria. Rooney and others found that a component of the chain, Coenzyme Q, was found in lower levels in the mitochondria of the TT/NN type horses. When CoQ was added to the experimental test, the electron transport chain activity was restored to the level of the CC/II horses.

Follow up studies by the same group have since reported that oral supplementation of CoQ10 increased CoQ10 concentration in the muscle by up to 40% (unpublished data). An earlier study (Sinatra et al., 2013) reported that CoQ10 supplementation at 800 mg/day (or 1.47 mg/kg body weight) increased serum CoQ10 concentration by almost three times after 60 days.

While there is no data on equines as of yet, there have been no side effects event at very high doses in beagles. It will be interesting to await further studies that test the effects of supplementation on athletic performance including whether supplementation could have an impact on CC horses.