Final answer:
The writer compared the new breed of mouse to Lance Armstrong because both have exceptional endurance and are able to sustain physical activity for extended periods of time without getting fatigued.
Step-by-step explanation:
The writer compared the new breed of mouse to Lance Armstrong because both have exceptional endurance and are able to sustain physical activity for extended periods of time without getting fatigued. According to the text, the mouse has a higher number of mitochondria in its muscle cells, which are the main energy sources in a cell. This allows the mouse to produce energy without releasing too much lactic acid, which can lead to fatigue and muscle burning. Similarly, Lance Armstrong's body also produces energy without releasing too much lactic acid, allowing him to have impressive endurance.