New research led by at team at Keele University has revealed that human skeletal muscle has an epigenetic memory determined by earlier growth. This very literal discovery of "muscle memory" not only offers new insight into how exercise and rehabilitation programs can better target genes responsible for muscle growth, but potentially has dramatic implications for the long-lasting effects of performance-enhancing muscle building drugs.

The study examined eight untrained male subjects over a 22-week period. Each subject participated in a period of targeted resistance exercise, followed by a period of inactivity, and then another stretch of exercise. Muscle biopsies were taken at several points across the study and over 850,000 genomic sites were analyzed for epigenetic alterations.

"In this study, we've demonstrated the genes in muscle become more untagged with this epigenetic information when it grows following exercise in earlier life, importantly these genes remain untagged even when we lose muscle again, but this untagging helps 'switch' the gene on to a greater extent and is associated with greater muscle growth in response to exercise in later life – demonstrating an epigenetic memory of earlier life muscle growth!" explains senior author Adam Sharples with his PhD student, Robert Seaborne.

The research revealed several specific genes that demonstrated an epigenetic sensitivity related to muscle memory. The hope is that an increased knowledge of these "muscle memory genes" will help improve treatments for athletes recovering from injuries. But perhaps one of the most compelling implications of this study comes when one considers how it relates to athletes taking performance-enhancing drugs.

"If an elite athlete takes performance-enhancing drugs to put on muscle bulk, their muscle may retain a memory of this prior muscle growth," says Seaborne. "If the athlete is caught and given a ban – it may be the case that short bans are not adequate, as they may continue to be at an advantage over their competitors because they have taken drugs earlier in life, despite not taking drugs anymore."

The study was published in the journal Scientific Reports.