One of your super-fit friends does a power walk outside every morning; the other walks on a treadmill at the gym. They both swear their way is better. Then there's the fitness guru at work who says running on a treadmill is the only way to get enough cardio to stay fit. It's enough to make you give up exercise all together. Don't do that. Each method has its advantages and drawbacks, and in most cases, the drawbacks can be overcome. Ultimately, the best exercise is the one you'll do regularly.
The simple act of walking engages many muscles. Your shins and calves get into the act, as do your hamstrings, quads, glutes and hip flexors. This will happen whether you walk on a treadmill or a track or on varying terrains outside. However, walking on a treadmill tends to use the quads more than the other muscles. Dr. Len Lopez, a chiropractic sports physician and strength and conditioning trainer, points out that the conveyor belt motion of the treadmill assists with pulling your body forward, which is where your glutes and hamstrings are most engaged.
Researchers often use VO2, or oxygen uptake, to measure energy expenditure, and expending energy means burning calories. In a 1996 study published in the Journal of Sports Science comparing VO2 among trained runners who ran on a treadmill vs. running outside, researchers found that as speed increased, VO2 was higher for outdoor runners than on a flat treadmill, but that a 1 percent increase in incline on the treadmill evened out the energy expenditure. While the study dealt with running, one of the factors assumed to make the difference was air resistance encountered while running outside. So this could apply to walking as well.
The intensity level is the percentage of your maximum heart rate you achieve during your workout. To reap any benefits from your exercise, you should get at least 150 minutes per week of moderate activity. This means activity that brings you within 50 to 70 percent of your maximum heart rate. To lose weight or improve your fitness level, you'll need to up the intensity to between 70 and 85 percent of your maximum heart rate. Another study, published in the Journal of Applied Physiology, found that the heart rates of women were "significantly higher" when walking on a treadmill than when walking at the same speed on the floor.
Generally speaking, you'll use more muscles walking outside than on a treadmill, but you'll probably get your heart rate up faster, and thus get at least a slightly better cardio workout, on the treadmill. You could probably make up for the heart rate differences by walking faster outside or hitting more hills. You can make up for the muscle use difference on the treadmill by increasing the incline. An added benefit of walking outside is sunshine. More and more studies, including one published in the Journal of Cosmetic Dermatology in 2003, show the benefits of UV-B rays on your health. The best program might be one that combines walking inside some days and on the treadmill others, but if there's one you really prefer over the other -- just do it.
- ShapeFit.com: Aerobic Training for Your Butt -- Will Cardio Help Get a Firm and Toned Butt?
- Journal of Sports Science: A 1% Treadmill Grade Most Accurately Reflects the Energetic Costs of Outdoor Running
- Journal of Applied Physiology: Treadmill vs. Floor Walking: Kinematics, Electromyogram, and Heart Rate
- MayoClinic.com: Exercise Intensity: Why It Matters, How It's Measured
- Journal of Cosmetic Dermatology: Sunshine is Good Medicine. The Health Benefits of Ultraviolet-B Induced Vitamin D Production.
- MNT: Benefits of Sunlight for Human Health
Nancy Cross is a certified paralegal who has worked as an employee benefits specialist and counseled employees on retirement preparation, including financial and estate planning. In addition to writing and editing, she runs a small business with her husband and is a certified personal trainer with the Aerobics and Fitness Association of America (AFAA).