I'm a regular member at a gym called Lifetime Fitness. Before I work out, I always run at least a half mile. Lately, I've been getting into the miles. My regular speed on a treadmill is 7.3 - 7.5 mph and then towards the end of my run I will get into it at about 8.0 - 8.5 mph. When I do, I often have people staring. What does that mean?

And I know sprinting is possibly dangerous on a treadmill. However, the treadmills at this gym allow me to do that. I have a treadmill at home, and I could never sprint on that. These treadmills are different and I can adjust to any speed quickly. Is this a reason why people stare or is it because they wish they could do the same?