You know the feeling. It's the third set, your legs are burning, and your brain is two shots behind your instincts. You're reacting instead of thinking — and oxidative stress is largely to blame. What if a microscopic blue-green organism cultivated since the time of the Aztecs could change that equation? Meet spirulina: the most nutrient-dense food on Earth and a quietly compelling tool for competitive tennis players and student-athletes who demand more from their bodies and