A common question I get from clients is, "If I want to do cardio to prepare for hiking or backpacking, which machine at the gym should I use?" The seemingly obvious answer to many is the Stairmaster, for others it's the treadmill.... so let's break both down!
First off, before the critics jump too far ahead- yes, the best cardio for hiking, is hiking. If you live in the mountains and can step out onto a trail from your back porch, you've already got it made. For many of us, though, challenging enough hills can be many hours drive away, so fitting in a trip to the woods between work and home life isn't always an option.
Now on to the machines! Stairmasters are a great way to build your cardiovascular abilities and quad and glute strength endurance, and are perfect when preparing for steep climbs up rocky paths, and well maintained trails with steps. However, the Stairmaster fails to train the calves as well as say, an incline treadmill, which are a make or break muscle group for extended climbs on smooth, steep terrain.
Stairmasters also only allow for single planar motion, which is a fancy term for you don't change direction. This is one of the crucial reasons that strength training and injury prevention work should always accompany cardio training in hiking preparation.
A treadmill at incline is my favorite cardio machine for hiking training, because it most closely mimics the changing gradual to steep incline of most trails, and it works the calves more than the Stairmaster. Proper form on the treadmill is important though....be sure to keep your hips aligned and underneath you, not protruding back like you're sticking your butt out.... walk nice and tall, and keep your hands off the front of the treadmill! Hands on the machine not only reduces the effectiveness, it can throw off gait enough to cause long term imbalance issues.
My other favorite cardio machine is the erg, or rower. While most people don't know how to use it properly (click here to see how), when done properly, the erg is a full body workout that can tax your system in minutes. I prefer it because it provides a mental challenge to keep pushing hard, which carries over well in that last half mile to a summit.
Lastly, if your goal is to simply strengthen your cardiovascular system, keep this in mind- your heart and lungs do not care what machine you are on. They are able to work and function with a treadmill just as much as they are with a bike. If your options are limited, or you just hate everything but one type of cardio, that can be ok. Anything is better than nothing in this case.