l-Leucine Increases Skeletal Muscle IGF-1 but Does Not Differentially Increase Akt/mTORC1 Signaling and Serum IGF-1 Compared to Ursolic Acid in Response to Resistance Exercise in Resistance-Trained Men

What Was Tested

Researchers studied IGF-1 LR3 in this randomized controlled trial publication.

This study examined serum and skeletal muscle insulin-like growth factor-1 (IGF-1) and Akt/mTORC1 signaling activity following ingestion of either ursolic acid or l-leucine immediately after resistance exercise.

Who Took Part

The age groups tagged for this paper are young adults and adults, men only.

How the Study Was Run

The researchers set it up as a randomized, double-blind, placebo-controlled and crossover study.

Random assignment meant chance, not the researchers, decided who got IGF-1 LR3 and who got the comparison, which limits bias.

Neither the participants nor the staff measuring them knew who was on IGF-1 LR3, so expectations could not easily colour the readings.

A placebo (an inactive look-alike) gave the IGF-1 LR3 group a baseline to be compared against.

Each person switched between IGF-1 LR3 and the comparison at some point, usually with a gap in between.

Blood samples were obtained pre-exercise and at 0.5, 2, and 6 hours postexercise.

Muscle biopsies were obtained pre-exercise and at 2 and 6 hours postexercise.

What Was Measured

PubMed files the paper under topics including Diet, Dietary Supplements, Insulin, Insulin-Like Growth Factor I, Leucine, Mechanistic Target of Rapamycin Complex 1 and Multiprotein Complexes.

The authors tagged it with the keywords branched-chain amino acid, cell signaling, muscle protein synthesis and resistance exercise.

What This Means in Plain Language

The paper is a randomized, double-blind and placebo-controlled study of IGF-1 LR3.

Its findings take up roughly 5 sentences of the abstract and are left out here on purpose; the source paper is the place to read them.

The publication is from 2016 (Journal of the American College of Nutrition), a journal based in United States.

More context: the IGF-1 LR3 compound page, all human trials.