Phytoecdysteroids: A Novel, Non-Androgenic Alternative for Muscle Health and Performance

Abstract

Skeletal muscle is the most abundant tissue in the adult human body, comprising more than 40% of total body mass in normal, healthy individuals [1], and is required for movement and locomotion. Muscle mass (volume) is an important determinant of muscle function, such that physiological cross-sectional area is correlated to peak isometric force [2,3]. The maintenance of skeletal muscle mass exists as a delicate balance between the rates of muscle protein synthesis and muscle protein degradation. Rates of muscle protein synthesis and degradation are finely tuned according to activity level, nutrient availability, and health status. For example, rates of muscle protein synthesis are positively influenced by exercise and nutrition, and negatively regulated by inactivity (e.g. disuse), aging (i.e. sarcopenia), and muscle wastingrelated diseases (e.g. cancer) [4]. The PI3K/Akt signaling pathway controls both catabolic and anabolic mechanisms in skeletal muscle. Activating this pathway through exercise and nutritional interventions has a positive effect on skeletal muscle. Phytoecdysteroids (PEs) are natural steroid analogs synthesized by many plant species that possess biological, pharmacological, and medicinal properties with no known side effects in mammals [5], and are believed toelicitanabolic effects on skeletal muscle, in a non-androgenic manner,via activation of the PI3K/Akt signaling pathway.