Epicatechin has been described as a polyphenol compound that promotes skeletal muscle restructuring, by expressing muscle regulation factors, activation of satellite cells and modulation of the main pathways associated with catabolism. However, the literature shows contrasting results of therapeutic effects and treatment protocols. Thus, the aim of this systematic review was to analyze the current literature addressing the molecular mechanism and clinical protocol of epicatechin on skeletal muscular atrophy in humans and animals. A search was conducted in PubMed/MEDLINE, Embase, Web of Science, and Cochrane Library databases. The qualitative analysis showed a prevalence of the inhibitory action of epicatechin in myostatin expression and atrogenes FOXO, MAFbx and MuRF1. Epicatechin showed positive effects on increased follistatin and on the activation of the myogenic regulatory factors (Myf5, MyoD and myogenin). In addition, the studies evidenced the impact of epicatechin on the mitochondrias' biosynthesis in muscle fibers, activation of the signaling pathway of AKT/mTOR protein synthesis, and improvement of skeletal musculature performance, particularly when associated with physical training. Epicatechin showed promising clinical applicability through beneficial results under conditions that negatively affect the skeletal musculature. However, there is no protocol standardization allowing to draw more specific conclusions on its therapeutic use.

The skeletal muscle plays a critical role in regulating systemic blood glucose homeostasis. Impaired skeletal muscle glucose homeostasis associated with type 2 diabetes mellitus (T2DM) has been observed to significantly affect the whole-body glucose homeostasis, thereby resulting in other diabetic complications. T2DM does not only affect skeletal muscle glucose homeostasis, but it also affects skeletal muscle structure and functional capacity. Given that T2DM is a global health burden, there is an urgent need to develop therapeutic medical therapies that will aid in the management of T2DM. Prediabetes is a prominent risk factor of T2DM that usually goes unnoticed in many individuals as it is an asymptomatic condition. Hence, research on prediabetes is essential because establishing diabetic biomarkers during the prediabetic state would aid in preventing the development of T2DM, as prediabetes is a reversible condition if it is detected in the early stages. Literature predominantly documents the changes in skeletal muscle during T2DM, but the changes in skeletal muscle during prediabetes remain unknown. In this review, we seek to review the existing literature on prediabetic and T2DM associated changes in skeletal muscle function.