Resistance exercise and nutritional support
Resistance exercise and nutritional support

Leucine-enriched essential amino acid and carbohydrate ingestion following resistance exercise enhances mTOR signaling and protein synthesis in human muscle


Research indicates that resistance exercise stimulates muscle protein synthesis 1 to 24 hours after training. Resistance exercise has also been shown to activate the mTOR signalling pathway. mTor is a protein that, when stimulated, can increase the amount of muscle protein made, but it has to have all the necessary components, which includes all the essential amino acids, leucine in particular. 

Numerous studies have shown that when essential amino acids or essential amino acids plus carbohydrate are ingested after exercise, muscle protein synthesis is increased beyond the effects of exercise alone. The precise mechanisms behind this increase are not entirely known.

Trial Length

Acute Metabolic Study

Number of Subjects




Age Range

25 - 32

The Goal

The aim of this study was to investigate the mechanisms behind elevated muscle protein synthesis when an essential amino acid supplement enriched with leucine and carbohydrate was taken after engaging in resistance exercise. Researchers anticipated that the supplement would stimulate mTor signaling and lead to increased muscle protein synthesis to a greater degree than muscle recovery without nutrients.

The Results

Sixteen young healthy male volunteers were separated into two groups following exercise: the control group and the group receiving a leucine-enriched essential amino acid supplement + carbohydrate (EAA+CHO) the first hour after exercise. 

The EAA+CHO group experienced increased mTOR signaling and a 145% boost in muscle protein synthesis while the control group who only exercised experienced a 41% boost.

Muscle protein synthesis and net balance across the legs

mTOR and the eukaryotic initiation factor 4E-binding protein.

The Conclusion

Researchers concluded that increased stimulation of the mTOR signaling pathway leads to enhanced muscle protein production when essential amino acids and carbohydrate are ingested after resistance exercise.

The Why?

Muscle does more than makes you strong. It supports vital amino acid levels, regulates blood sugar levels, promotes bone health, increases lifespan, and improves outcomes from chronic diseases. Resistance exercise alone can help boost muscle protein synthesis by stimulating the activity of mTOR, a key regulator of the rate of synthesis. However, the response is modest in the absence of adequate availability of essential amino acid precursors of muscle protein.  When the activation of mTOR after exercise is supported by an essential amino acid supplement with a high concentration of leucine and also containing a modest amount of carbohydrate, mTOR activation increases 5-fold. Essential amino acids thus target the molecular mechanism promoting muscle protein synthesis and supply important precursors of muscle protein. These targeted nutrients can help increase your muscle mass alongside resistance training so your muscles and body stay healthy and strong.


Dreyer HC, Drummond MJ, Pennings B, Fujita S, Glynn EL, Chinkes DL, Dhanani S, Volpi E, Rasmussen BB. Leucine-enriched essential amino acid and carbohydrate ingestion following resistance exercise enhances mTOR signaling and protein synthesis in human muscle. Am J Physiol Endocrinol Metab. 2008 Feb;294(2):E392-400. Epub 2007 Dec 4. PMID:18056791