Herbert wants to purchase a piece of fitness equipment to focus on his cardio endurance what is the least helpful purchase for him to make in an effort to reach his cardio endurance gold a treadmill a bike and elliptical machine or a nautilus machine

To focus on cardio endurance, the least helpful purchase for Herbert would be a Nautilus machine. Nautilus machines are primarily designed for strength training and building muscle, whereas a treadmill, bike, and elliptical machine are all effective tools for cardiovascular exercise. To improve cardio endurance, he should prioritize the treadmill, bike, or elliptical.