They lost a battle, but the war continues

Plaga Zombie: Mutant Zone (2001)

Directed by Hernán Sáez

A small town is the subject of some experiment with aliens where they were allowed to test some earth folks with some kind of disease, but of course it spread with disastrous results. And now, three oddballs have been dumped into the middle of this town as test subjects or something, and the race for survival is on. John West is a strongman, with a cowboy hat and leopard skin tights, Bill is a medical student, and Max is a mathematical genius, and it's them against the zombies.