This clinical trial is focused on understanding how human muscles might remember past exposure to testosterone, a hormone important for muscle growth. The study is particularly interested in conditions like healthy aging and sarcopenia, which is the loss of muscle mass and strength as people age. The trial will also explore issues related to anabolic resistance, which is when muscles do not grow as expected in response to exercise or hormones, and anti-doping concerns in sports.
The study will use two treatments: Nebido, which contains testosterone undecanoate, and a placebo. Participants will be divided into groups, with some receiving the testosterone treatment and others receiving the placebo. The main goal is to see if muscles can grow back to their previous size and strength after stopping testosterone for a while. This will be compared between those who had testosterone before and those who did not.
Participants will undergo a series of tests to measure changes in muscle size, strength, and other characteristics. These tests will include methods like DEXA scans, which are used to measure body composition, and muscle biopsies, which involve taking a small sample of muscle tissue for analysis. The study will also look at how muscle cells change at a genetic level, including changes in DNA methylation, which is a process that can affect how genes are turned on or off. The trial aims to provide insights into how muscles respond to testosterone and how this might be used to improve muscle health in older adults.



Norway