Oral L-carnitine combined with training promotes changes in skeletal muscle.

The research explores whether taking oral L-carnitine supplements can enhance the effects of exercise on muscle changes in horses, finding positive, but temporary, results.

Study Methodology

• The study was conducted with seven 2-year-old Standardbred horses. Four horses were given a daily oral L-carnitine supplement of 10 grams for a period of 10 weeks, while the remaining three horses were used as controls and did not receive the supplement.
• All seven horses underwent an exercise regimen for the first 5 weeks of the study which consisted of multiple high and low speed workouts on a treadmill every other day.
• This was followed by a ‘detraining’ period of an additional 5 weeks where horses were kept in individual stalls and were not exercised.

Data Collection and Analysis

• Muscle biopsies were taken from the gluteus medius muscle of each horse at three time points: Week 0 (pretraining), Week 5 (post-training), and Week 10 (detraining).
• These biopsies were analyzed for changes in muscle fibre composition and glycogen content, using the periodic acid Schiff stain technique.
• The main changes were observed in horses who received the L-carnitine supplement, showing an increase in type IIA fibres, a decrease in type I fibres, an increase in the capillary-to-fibre ratio and intrafibre glycogen content.

Results and Potential Implications

• However, these changes largely reverted back after the detraining period, indicating the enhancements might not be sustained without continued L-carnitine supplementation and exercise.
• Despite the observed changes suggesting boosting muscle carnitine can help improve athletic performance, the study concludes that further research is needed to evaluate if muscle carnitine content would limit fatty acid oxidation – an important aspect in sustaining endurance and muscle performance.