Glycine Propionyl-L-Carnitine and Athletic Performance?

Both exercise enthusiasts and competitive athletes are often looking for ways to improve their athletic performance and shed body fat.  In most cases, this involves optimizing their training methods and nutrition.  Some also look towards nutritional or dietary supplements to help.

One common target for potentially improving athletic performance involves increasing blood flow to muscles through vasodilatory processes that are mediated by increases in nitric oxide.

The carnitine compound, Glycine Propionyl-L-Carnitine, which is also known as GlycoCarn® has been a novel compound of interest in recent studies.  Specifically, it has potential ergogenic effects by reducing blood lactate response to exercise, improving sprint performance, and increasing synthesis of nitric oxide.

A recent study published in the Journal of the International Society of Sports Nutrition looked at the effect of supplementation of varying doses of glycine propionyl-l-cartine on repeated anaerobic sprint performance [1].  For this study, they included 45 resistance trained males who consumed this dietary supplement for 28 days.

Methods:

The researchers from Florida Atlantic University, had test subjects randomized to placebo or glycine propionyl-l-carnitine supplementation.  Two initial testing sessions, seven days apart, lasting 90 minutes were completed following randomization.

The initial testing sessions included 5 10-second Wingate cycle sprints following 1 minute of recovery.  Prior to these sessions, the test subjects either ingested placebo or 4.5 grams of a glycine propionyl-l-carnitine supplement.

After the initial testing sessions, the 45 subjects were randomized to receive doses of 1.5 g, 3.0 g, or 4.5 g of glycine propionyl-l-carnitine (GPLC) for 4 weeks prior to a final testing session using the same protocol

Results:

  • Higher doses of GPLC actually had adverse effects on peak power (PP) and mean power (MP) compared to baseline values.  PP was 2-5% lower while MP was 3-7% lower.
  • At the 1.5 g /day dose of GPLC, improvements in PP and MP were observed compared to baseline values.  Specifically, PP increased 3-6% while MP improved 2-5%.
  • A statistically significant reduction in lactate accumulation of 24% was observed in the group randomized to 1.5g/day of GPLC

Conclusions:

Basically, the study authors had previously found that a single dose of 4.5 g of GPLC, taken 90 minutes prior to exercise, resulted in improvements in peak power and mean power across repeated sprints.  However, the results of this study suggest that there are no added benefits derived from longer-term supplementation.

[box type=”note”]The study authors noted that the daily dose of 1.5 g/d of GPLC taken for 28 days resulted in similar improvements anaerobic sprint performance to taking a single dose of 4.5 g prior to exercise. Conversely, taking larger doses for prolonged periods of time had adverse effects on anaerobic sprint performance.[/box]

References:

  1. J Int Soc Sports Nutr. 2010 Oct 28;7(1):3
  2. J Int Soc Sports Nutr. 2009 Apr 2;6:9.