Final answer:
Creatine and caffeine are supplements most likely to improve a sprinter's performance by increasing power output and endurance. However, it's essential for athletes to use legal and safe means to enhance performance.
Step-by-step explanation:
Among various supplements that can potentially improve a sprinter's performance, creatine, caffeine, and legally permissible dietary amino acids are notable. Creatine is used to increase short bursts of power by providing quick ATP during initial muscle contractions, particularly useful for sprinters.
Ingesting caffeine prior to sprints can improve performance, endurance, and delay the onset of muscle fatigue. While amino acids are essential for muscle protein synthesis, they are typically best obtained through a healthy diet as studies haven't shown supplements to provide a performance advantage for athletes.
It's important to acknowledge that many substances that can enhance performance, such as anabolic steroids, EPO, and hGH, are illegal for nonmedical use and banned in sports competitions. Athletes should aim for legal, safe, and ethical means to boost their performance, focusing on nutrition, training, and recovery strategies.