Benefits
Exercise recovery
In a single small crossover trial (10 resistance-trained men), L-carnitine L-tartrate favorably affected biomarkers of recovery from exercise stress, including reduced markers of muscle damage; clinical recovery and exercise performance were not directly measured.
Reduced soreness
The single cited trial (Volek 2002, n=10) measured biochemical markers of muscle damage rather than subjective soreness; reduced soreness is therefore not demonstrated by the evidence cited here.
Energy metabolism
L-carnitine transports fatty acids into mitochondria, a well-defined biochemical function in energy metabolism. However, supplementing L-carnitine has not been shown to increase energy, endurance, or exercise performance in healthy people; the cited trial measured recovery biomarkers, not performance or energy output.
Mechanism of action
Fatty-acid transport
L-carnitine carries long-chain fatty acids across the mitochondrial membrane, where they are burned for energy.
Reduced exercise oxidative stress
In the cited trial, L-carnitine L-tartrate lowered markers of purine catabolism and muscle damage (myoglobin, creatine kinase) and reduced MRI-assessed muscle disruption after exercise, which may aid recovery.
Clinical trials
Randomized balanced crossover in 10 resistance-trained men examining L-carnitine L-tartrate on biomarkers of recovery from exercise stress (exercise performance not measured). (Volek et al. 2002, American Journal of Physiology - Endocrinology and Metabolism)
10 resistance-trained men (small crossover trial).
In 10 resistance-trained men, L-carnitine L-tartrate favorably affected biomarkers of muscle damage and recovery (purine catabolism, myoglobin, creatine kinase) and reduced MRI-assessed muscle disruption after exercise versus placebo; exercise performance was not measured.