THE STUDY: Maastricht University (The Netherlands) researchers had athletes consume 2 grams of carnitine along with 80 g of Vitargo, or just 80 g of Vitargo first thing in the morning and four hours later for 24 weeks. Endurance capacity and several metabolic factors were measured during a low-intensity cycle test and a high-intensity cycle test.
THE RESULTS: The scientists reported in a recent issue of the Journal of Physiology that the subjects taking the carnitine burned 55% less muscle glycogen, and increased fat burning by an equivalent percentage during low-intensity exercise. During high-intensity cycling, the subjects taking carnitine had lower levels of lactic acid and higher levels of creatine phosphate.
A measurement of their ability to resist fatigue during a cycling test revealed that those taking carnitine were able to cycle more than 25% longer. This is likely due to the fact that they burned more fat while preserving more muscle glycogen, as well as having lower levels of lactic acid. Also, despite adding 160 g of fast-digesting carbs to their diets, the subjects taking carnitine gained no additional bodyfat, while the group taking just 160 g of fast carbs gained more than 5 pounds. This may be due to carnitine’s ability to keep blood glucose levels low even after a large carbohydrate meal, by enhancing glucose uptake at the muscle cells.
So it appears that carnitine is dependent on insulin for entry into muscle cells, yet carnitine enhances insulin’s actions at the muscle to aid glucose uptake.
THE DOSAGE: Taking carnitine can help you burn more fat during cardio workouts. Plus, it can help you train with more intensity and strength during weight workouts by maintaining higher creatine phosphate levels and lower lactic acid levels. The subjects took carnitine with 80 g of Vitargo to spike insulin levels because carnitine relies on insulin for entry into muscle cells. However, you don’t need to go to such extremes.
We suggest you take 2–3 g of carnitine first thing in the morning with a 20–40 g whey shake and 30–60 g of fast-digesting carbs, and with a 40-g postworkout protein shake along with 40–80 g of fast carbs. Combining protein and carbs will spike insulin enough to drive the carnitine into your muscle cells.
- REFERENCE: S. D. R. Galloway, “Effects of oral l-carnitine supplementation on insulin sensitivity indices in response to glucose feeding in lean and overweight/obese males,” Amino Acids, 41(2):507–515, 2011; B.T. Wall et al., “Chronic oral ingestion of l-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans,” Journal of Physiology, 589(Pt 4) 963–73, 2011.