ATHLETES: Overtraining can seriously affect performance. Researchers have identified several short term key markers that result from overtraining, including "impaired anaerobic lactic acid perforance and a reduced time to exhaustion". [ 7 ] The same study discusses many other soon-to-follow issues including problems with uric acid levels, ammonia, creatine kinase, free testosterone/cortisol, growth hormone and so on. More subjective issues include excessively sore muscles and sleep and mood disorders. Again, overtraining is real and leads to real physiological issues.
But I'm not more aggressive—a behavior change often tied to testosterone. That's not surprising to Robert Sapolsky, ., a neuroendocrinologist at Stanford University and a leading researcher on stress and behavior. "It's really not the case that testosterone 'causes' aggressive behavior," he says. "Instead, it makes the brain more sensitive to social cues that trigger aggression. And in support of that, a guy's testosterone level isn't a very good predictor of how likely he is to be aggressive."
Other side effects include increased risk of heart problems in older men with poor mobility, according to a 2009 study at Boston Medical Center. A 2017 study published in JAMA found that treatments increase coronary artery plaque volume. Additionally, the Food and Drug Administration (FDA) requires manufactures to include a notice on the labeling that states taking testosterone treatments can lead to possible increased risk of heart attacks and strokes. The FDA recommends that patients using testosterone should seek medical attention right away if they have these symptoms: