Selenium is a trace element of fundamental importance to human health. In recent years, an increasing number of studies have been carried out in the field of skeletal muscle health and sports nutrition. Selenium functions in the human body through selenoproteins. Selenoproteins play an important role in maintaining skeletal muscle function by delaying exercise fatigue and muscle aging. They mainly regulate skeletal muscle by anti-oxidation, regulating signal pathways, and affecting protein metabolism. In this paper, we summarize the latest advancements in research regarding selenium and its impact on skeletal muscle health, along with its applications in sports nutrition.