Every type of motion requires some sort of energy
Every type of motion requires some sort of energy. In the living world as we know it, this energy is provided by the consumption of nutrients in particular carbohydrates, fatty acids and amino acids. The energy contained within these substrates is converted by metabolic processes into motion and heat. It is therefore no surprise that investigations of biological processes in health and disease often directly contain or end up with recognitions or questions in the field of metabolism. The heart is the most active muscle in mammals with a contraction every second throughout life. Thus, cardiac motion seems the most constant motion known. To support life, the mammalian heart must contract incessantly. As a consequence, the requirement for energy (in the form of ATP) to fuel this function is immense. Interestingly, high energy phosphate storage within the cardiomyocyte is minimal and may support contraction only for a few beats a few seconds. Thus, tight coupling between substrate conversion into ATP and myocardial contraction is essential for normal cardiac function. This has led to the elegant suggestion of a direct and reversible interrelationship between contractile function and metabolic activity as shown on the cover of this issue . Thus, metabolic activity is not simply dictated by contractile activity. In contrast, it may also be used to influence contractile function and therefore overall cardiac performance. The latter recognition is the Fosfomycin calcium for metabolic therapy of diseases such as diabetes or heart failure. This link between energy metabolism and contractile function was the focus of the meeting of the Society for Heart and Vascular Metabolism 2017 in Weimar (Germany). The specific topics discussed during this meeting have led to the generation of this special issue. The following authors describe the current “state of the art” regarding the link between metabolism and function and are summarized as follows: Volker Adams and his group review the impact of exercise on cardiovascular disease and risk . Exercise is a condition that significantly affects metabolic activity of the organism. Currently it is also clear that exercise affects human health. Again, this change in metabolic activity appears to offer significant therapeutic potential which has not been used to full capacity. They present that with respect to exercise in cardiovascular disease, many concepts have changed and even patients with myocardial infarction are nowadays included into exercise training programs very shortly after the insult. Exercise intolerance is a frequent condition in heart failure with reduced ejection fraction. Linda Peterson and her group present in their manuscript an overview on the effects of inorganic nitrate on exercise capacity in patients . They indicate why inorganic nitrate has advantages over other sources of NO. Furthermore, they present the mechanisms of action of NO relating to improved exercise performance in heart failure. While there is a larger trial underway, the presented effects may be interesting to follow as they together with the impact of exercise training reported by Volker Adams  suggest an intensified effect of exercise therapy in heart failure patients. The mechanisms for exercise effects on cardiovascular health are still far from clear. Instead, it is known that exercise capacity depends on coupling of ATP generation and contraction in both skeletal muscles and the heart. Central to the coordinated energy transduction function is the mitochondrion. Mitochondria generate not only more than 95% of ATP but also regulate intracellular calcium homeostasis, signaling and cell death. Thus mitochondrial function is of major importance but there are yet limited possibilities to investigate mitochondrial function . In the manuscript of Vera Schrauwen and her group the current knowledge to use magnetic resonance spectroscopy for analysis of cardiac metabolism is discussed . Sina Coldewey and her group describe a new method to assess mitochondrial function in their manuscript . They describe the use of the Protoporpyhrin IX Triplett State Lifetime Technique to determine mitochondrial oxygen delivery, oxygen tension as well as oxygen consumption . The variables influencing mitochondrial oxygen use are described in a pilot study of 26 healthy subjects with and without exercise . This investigation may pave the way for a routine analysis of mitochondrial function.