Most people who put in long hours exercising want to get maximum results for their efforts. A lasting, recurrent question asks which burns more calories: walking or elliptical machine?

Several studies have attempted to answer the question. A 2011 study published in Medicine & Science in Sports & Exercise found that a 200-pound person burned 455 calories in an hour using an elliptical trainer, but burned 255 calories an hour walking at 2 mph, and 391 calories walking 3.5 mph. Other studies have reached similar conclusions that, generally speaking, the elliptical machine will probably burn more calories than walking.

Experts at the Mayo Clinic suggest taking into consideration several factors, including goals, before deciding which workout is best for you.

The elliptical machine provides a good workout, and is considered a low impact exercise on knees, hips, and back. Since it's a weight-bearing exercise, it also helps build bone density. However, it is more gentle than walking and may be the best choice for people with arthritis in their knees and hips, according to a study published in the British Journal of Sports Medicine.

The poles that are usually found on elliptical machines, which look similar to ski poles, allow you to also exercise your upper body. And if you want to give your calf and hamstring muscles a more intense workout, you can pedal the elliptical in reverse.

There are also advantages to walking. First, it's cost-free, and studies show you're more likely to stick to walking than other forms of exercise. Most experts believe that walking beats the elliptical for building bones because while your feet stay stationary on the elliptical, the stress that walking places on the bones builds density and strength.

Walking can also provide a full-body workout if you swing your arms or add weights, or speed walk. Researchers at the University of Michigan found that walks in nature are associated with a wide variety mental health benefits, including decreased stress and depression. Walking outdoors also raises levels of vitamin D, which builds healthy bones and also boosts the immune system.