Eight recreationally active men and women ages 18–35 were recruited for participation in the present study. Exercise-induced hormonal responses are controlled by the hypothalamic-pituitary adrenal axis (HPA), a key regulator of homeostasis, which responds to stress by triggering a series of endocrine changes resulting in the release of testosterone (T) and cortisol (C) (26). Practitioners have often faced difficulties in maintaining TL balance as individual responses to acute and chronic exercise are unique. The imposed stresses from exercise TL can be viewed on a continuum with fatigue anchoring one end and recovery the other (17). Exercise training represents a significant perturbation to both the human neuroendocrine and autonomic nervous systems (ANS) (2, 56). While testosterone plays an important role in health, it can also place extra demands on the heart, especially when used as a treatment. An increased blood volume can also make the heart beat faster to keep up with the body's needs. This extra effort may lead to an increased heart rate, especially in people who already have heart problems. Low testosterone levels can lead to fatigue, low energy, and sometimes problems with heart function. Besides its effects on muscles, bones, and mood, testosterone also influences the heart and blood vessels. When these symptoms are combined with low testosterone levels confirmed by blood tests, TRT may be considered. When the body doesn’t produce enough testosterone, doctors may recommend TRT to help bring hormone levels back to normal. It also noted that heart rate changes, when reported, were usually mild and temporary. While this does not happen in every patient, it may explain why some people feel jittery or experience palpitations after starting therapy. However, they did notice that men with a history of heart disease were more likely to experience changes in heart rate after starting TRT. The effect was more noticeable in men who received large doses or infrequent injections, which caused hormone levels to rise and fall sharply. This research found that some men experienced spikes in heart rate shortly after receiving their injections. This suggests that while heart rate changes may occur, they are not common in all users. However, the researchers also tracked heart-related side effects. The problem is the same (a training load-recovery mismatch) but getting the interpretation wrong towards under-loading is at least as costly as getting it wrong toward over-loading. An athlete not progressing because they have been systematically underloading needs more training. Align testing with training, and monitor session RPE for signs of genuine load-recovery imbalance. For example, an individual on a hypertrophy program tested on one-rep max strength is likely to see a poor result that has nothing to do with over- or under-training. If the training program does not match how the athlete is measuring progress, they may see "no result" when there are other fitness adaptations occurring. For example, an individual who is unable to add weight to an exercise week over week may interpret this result as being overtrained when it’s just as likely they are undertrained. Monitoring progress in response to exercise can be challenging, especially if one is using the wrong tools or is interpreting their results incorrectly. And in high doses, testosterone can have a negative effect on cardiac risk factors, including HDL ("good") cholesterol levels. Although testosterone acts directly on many tissues, some of its least desirable effects don't occur until it is converted into another male hormone, dihydrotestosterone (DHT). The risk depends on personal health, the form and dose of TRT, and how the body responds. In summary, TRT may raise heart rate in some people, but this effect is not the same for everyone.
