When we think about athletic performance and everyday well-being, we tend to focus on muscles, hydration, sleep, and mental toughness. But an unexpected player is gaining attention among scientists and trainers: your gut microbiome—the trillions of bacteria living in your digestive tract. And whether you’re a young athlete, an active adult, or a senior aiming to stay strong and energized, your gut may be just as important as your muscles or your mindset.