Supplementation for more than a week with L-carnitine has the potential to increase carnitine in horses’ muscles. This increase could improve the transportation of fatty acids into mitochondria to be used for energy production. One study looked at using a carnitine-containing product in horses to “offset fatigue-induced performance detriments” and facilitate a more rapid recovery and return to exercise.
Study: Effects of Carnitine Supplementation in Horses
In most situations, muscle glycogen repletion can take as long as 72 hours. Intense bouts of exercise, with associated increases in blood creatine kinase, create muscle damage and trigger the release of inflammatory cytokines that are part of the metabolic recovery process.
The study included 16 adult Thoroughbreds trained for six weeks. An hour prior to and after completion of an exercise test, they were administered acetyl L-carnitine HCl, L-carnitine tartrate, sodium chloride, L-glycine, L-leucine, ascorbic acid, d-alpha tocopherol acetate, and alpha lipoic acid (Platinum Renew by Platinum Performance) in unsweetened applesauce. The control horses received only applesauce.
The exercise test on a three-degree-inclined high-speed treadmill brought the horses to exhaustion. A second similar exercise test was performed 48 hours after the first test. The researchers evaluated the horses’ heart rates, fetlock kinematics, and cytokine levels.
Study Findings
The horses receiving the supplement retained more fetlock flexion than the control horses during the second exercise bout, which provided some protective advantage to musculoskeletal structures. The supplemented horses’ heart rates did not decline as quickly after the second exercise test as they did after the first. The supplement did not affect time to reach V200 or HRmax, time spent at HRmax, total gallop time, or HR recovery rate. Blood lactate and hematocrit did not change with supplementation on either test day. Cytokines increased at one hour after the first test but reached baseline by six hours. Most significantly, supplemented horses experienced a disruption of some cytokine expression patterns after the second exercise test. The authors advised that a carnitine supplement “may elicit a positive response for post-exercise recovery,” yet there were “no modulatory benefits for systemic blood pro-inflammatory responses to exercise.”
Final Thoughts
In summary, the authors reported that “sequential bouts of exercise performed within 48 hours of one another are detrimental and provide insufficient recovery time to mount a full inflammatory response. In turn, this is likely to prolong the recovery period and may leave the equine athlete susceptible to infection and other immune insults.”
Reference
Johnson SE, Barshick MR, Gonzalez ML, et al. A Carnitine-Containing Product Improves Aspects of Post-Exercise Recovery in Adult Horses. Animals 2023, 13, 657. DOI: 10.3390/ani1304065
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- Approach to Horses With Poor Performance
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