Why Resistance Training Makes You Bulk Up

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Peroxisome proliferator-activated receptor-gamma coactivator (try saying that tongue twister 10 times in a row) is the gene that is activated during both endurance and resistance exercisesDespite the fact that the same gene, more commonly referred to as PGC-1, is activated during both lifting and cardio, researchers from the University of Jyväskylä in Finland determined why resistance exercises make you bulk up, while endurance exercises make you lean. According to the study, which was published by the American Physiological Society, the answer boils down to protein. No, we aren’t talking about grilled chicken or how much protein you take in after an exercise.

The study explains how proteins run the body. Different functions of the body are turned on or off, or sped up or slowed down based on protein. According to the study, the body has many different proteins, and the instructions to make them are written on sections of DNA, referred to as genes. Different genes code for different proteins, but different proteins can also come from the same gene. Called isoforms, these proteins are produced when only part of the gene’s code is read.

New research in Physiological Reports shows that although both resistance and endurance exercises activate the PGC-1α gene, the adaptation processes that are stimulated after exercising are not the same and based on the isoform that is produced, you will either bulk or become leaner.

Researchers conducted the study by taking samples of these isoforms shortly after the participants exercised. According to the study, the researchers found that both endurance and resistance exercises produced isoforms PGC-1α exon 1b, PGC-1α exon 1b, and truncated PGC-1α, while only endurance exercise produced PGC-1α exon 1a isoform.

This simply means that while endurance exercise activated genes that stimulated growth of new blood vessels and increased endurance. Resistance exercise activated both a gene that promoted blood vessel growth, and a gene that encouraged muscle growth.

By activating two genes, resistance exercise promotes bulking. The single gene will just encourage leaning out because endurance is increased. That is why a lot of track athletes will have longer endurance and leaner muscles, and body builders endurance will be less, but they will have much more muscle mass.

According to the research, the study has potential to aid future information regarding exercise induced muscle adaptation. Understanding more about why muscles grow and develop the way that they do, allows researchers to determine the best exercises for specific sports, or individuals who may be trying to recover from injury.

The press release shows how the results of the research s improve the understanding of exercise-type specific early signaling events and support the idea that gene expression responses of PGC‐1α isoforms may have an important role in exercise-induced muscle adaptations.

So, next time you go for a long run, or get a lift in, you know why your body is responding the way it is. 

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