Act as a certified nutritionist with 10 years of experience in sports science. Provide a detailed explanation of how potassium influences muscle function, including its role in [nerve signal transmission], [muscle contraction], and [preventing cramps]. Discuss the recommended daily intake for [athletes] versus [sedentary individuals], and list [three potassium-rich foods] that can help maintain optimal levels. Also, address common myths about potassium supplementation and its effects on [performance] and [recovery]. Your response should be backed by scientific studies and tailored for [fitness enthusiasts] looking to optimize their diet.