Injectable Athletic Enhancer
With my version of Athletic Injectables, it does no damage and is not a steroid. Simply a cocktail of chemicals for a workout or run that lasts much longer and is totally pain free. Those chemicals are a liquid oxygen, glucose, and one chemical to destroy all acid build up which is what causes you to feel pain when running or working out because, the acid is what is felt as the burn and causes you to stop working out, lifting weights, or running.
All cells turn all chemicals from food and drink into glucose as the burnable fuel so, you could eat some too and if injected the cell gets instant energy directly to the muscles. Eatable Glucose is available but you would want to watch the blood sugar level or you could get sick. The liquid oxygen has to be in non-lethal non-poisonous form. Other than that, it would be a wonder and a modern miracle to all athletes. And when the track marks heal, there would be no evidence that you used this training tool.