This article looks closely at the possible link between TRT and increased heart rate. TRT is used to bring testosterone levels back to normal and improve symptoms like fatigue, low sex drive, and depression. This study must be powered for CVD outcomes and, ideally, should examine TRT among a broad spectrum of hypogonadal men to stratify treatment effects by age and baseline health status, among other clinical variables. An alternative interpretation of these longitudinal data, like those from cross-sectional studies, is that low T levels are a marker of ill health. To understand the connection between TRT and heart rate, researchers have looked at various types of studies. TRT can possibly increase heart rate by affecting the nervous system, boosting metabolism, or changing how active a person feels. This helps to find out if the therapy is affecting the heart and if any changes in heart rate are happening. The higher incidence of coronary artery disease, and especially of SCD, in male patients but also in females following menopause, has highlighted the role of estrogen as a cardioprotective hormone. This results in a sudden increase in calcium, which then triggers cardiac contraction. When the sarcolemma is depolarized, the voltage-gated L-type calcium channels are opened and the influx of calcium into cytosol increases. The contractile function of the heart is determined by intracellular calcium concentration, which is influenced by the expression and activity of calcium regulatory proteins. The likely reason may be the fact that it blocks the major α1 subunit of the L-type channel, similarly to the effects of the commonly prescribed calcium channel antagonists. Interestingly, ovariectomized mice had an increase in the expression of L-type calcium channels, which were reversed upon administration of exogenous estrogen (39). In contrast to the cross-sectional studies mentioned above, these studies have attempted to analyze large populations of men who received exogenous T, presumably as TRT. Nonetheless, the results of the TOM trial provide important cautionary information regarding the potential for TRT to be harmful in at least some populations of older men and points to the need for larger studies. Importantly, the interpretive value of these randomized controlled trials remains limited, as these studies were not powered to look at CVD events as an outcome. Also, oral testosterone passes through the liver, which processes the hormone before it reaches the bloodstream. After taking a dose, testosterone can enter the blood quickly, leading to a short-term rise in levels. For those with heart issues or sensitivity to changes in hormones, these ups and downs may be uncomfortable. This happens because testosterone may stimulate the nervous system, increase metabolism, and raise blood pressure slightly. Any change in hormone levels can lead to changes in the way these systems work. The connection between testosterone and the heart is complex. It explains how testosterone affects the heart and what the latest research says about it. It could also come from changes in sleep, weight, blood pressure, or mood—all of which can be influenced by testosterone. Cortisol is the hormone most directly tied to stress and HRV. If you suspect hormonal issues, work with a healthcare provider. Understanding these patterns helps interpret HRV data accurately. While acute cortisol spikes are normal and healthy, chronic elevation suppresses HRV.
