Will training to failure lead to more muscle growth (hypertrophy) than not training to failure?
You will gain the same amount of muscle by training without going to failure and also prevent injuries.
Muscles are composed of specialized long and tubular cells, known as myocytes. Myogenesis is the process of myocytes grouping together. And these groupings are found throughout our body in different arrangements, making up our muscular system.
Hypertrophy is the name given to the growth of muscle cells. The muscle fibers themselves get thicker, they don’t become more numerous (that is called hyperplasia).
Hypertrophy is usually decribed as having two or three parts: stimulation and repair; or stimulation, signaling and repair.
Stimulation is the term given to the contracting of the muscles and tearing of muscle fibers when one is lifting weight. You do several repetitions and sets etc., and you cause damage to the internal muscle fibers.
Signaling is the mobilization of different hormones in the blood stream to “damaged” areas of the body to activate growth. The exact nature of the cellular processes that cause muscle to grow is very complex, but for our purposes we can focus on the role of the following hormones: testosterone (T), growth hormone (GH), and Insulin-like growth factor 1 (IGF-1) in building muscle. These hormones all contribue to the repair of cells primarily through the deployment of proteins which are the building blocks of muscles.
Repair is the actual rebuilding of damaged muscle fibers.
Studies from Spain (https://www.ncbi.nlm.nih.gov/pubmed/26666744), Australia (https://www.ncbi.nlm.nih.gov/pubmed/16410373), and Brazil (https://www.ncbi.nlm.nih.gov/pubmed/29189407) have closely examined the question of training to failure versus not training to failure.
Each study found that when two groups of men followed a closely-monitored resistance training program, they had more or less identical gains in muscle mass, regardless of whether or not they trained to failure.
Two other important observations were made in these studies:
1) training to failure does provide a slight increase in muscle endurance (not size)
2) not training to failure provides a significant safety net against injury
In each of the studies mentioned, the participants had blood tests performed before, during, and after the resistance training program.
The Australian study cites, “Strength training leading to RF resulted in reductions in resting concentrations of IGF-1 and elevations in IGFBP-3, whereas NRF resulted in reduced resting cortisol concentrations and an elevation in resting serum total testosterone concentration.“ (RF in this case was training to failure, NRF not training to failure.)
Therefore, even though it’s true that there are subtle differences in the hormone levels of individuals training to failure vs not training to failure, such differences are not important enough to alter the levels of hypertrophy.
This might come as a welcome relief to those who have been constantly reading articles on hypertrophy and hormones, and trying to tweak their workout programs to engage certain chemical pathways, etc.
For now the answer seems to be “equal muscle growth for training to failure and not training to failure” and “the risk of injury due to bad form when training to failure makes it not worth it.”
