If a huge bear were chasing you its enormous mass would be very threatening. but if you ran in a zigzag pattern, the bears mass would be to your advantage. why

The bear, even though it is a very heavy and bulky animal, it can run pretty fast, and can easily outrun a human, but this is while running straight or when making gradual turns. The situation changes if the human starts running in a zigzag pattern. The human is much lighter, quick acceleration, long thin legs, and is much more agile, which will all be its advantage because in this kind of a chase the agility and acceleration are crucial. The bear on the other hand, will find it very difficult because its weight will disable it to make quick turns, it has a slow acceleration, and is not agile. So a human with a solid amount of stamina with using this tactic has a pretty good chances of escaping a charging bear.

"a.) well–developed vascular system."