Changing the incline on the treadmill can quickly transform an easy workout into an all-out sweat session. If you’ve wondered what the best incline for the treadmill is, the answer is simple: There is no single recommendation that’s right for every one or every workout. Whether you crank the treadmill incline up to a steep grade or opt for a subtle set of rolling hills, the incline you choose will depend largely on your goals.
Simulate Outdoor Running
If bad weather has brought your usual outdoor run inside, you might notice that the treadmill is slightly easier to run on than your usual terrain. The reason: lack of wind resistance. A 1996 study published in the "Journal of Sports Sciences" determined that adding a 1 percent incline to the treadmill accurately simulated an outdoor run on flat ground. This figure held true for speeds between 6.53 and 11 miles per hour. To simulate hills, simply add more of an incline.
A University of Colorado study published in the January 2012 issue of "Gait and Posture" found that walking at a 9-degree incline -- just over a 16 percent grade -- activated the long head of the hamstring 635 percent more than walking on level surfaces. The gluteus maximus showed 345 percent more activation. Walking faster increased the muscle recruitment. You don’t have to climb such a steep angle: a 5 percent incline was beneficial at speeds as low as 1.67 miles per hour.
Get Into Shape
If your goals are to get back into shape, consistent high-intensity interval training, or HIIT, is proven to reduce body fat and shed inches. A 2012 study published in the "American Journal of Physical Medicine and Rehabilitation" led overweight subjects through a nine-month program centered on HIIT. Subjects lost significant body fat and increased exercise tolerance. HIIT alternates short periods of hard work with periods of recovery. The treadmill incline allows increases in intensity at low speeds, reducing the risk of joint injury. Choose your own challenging incline level and walk for 30 to 60 seconds, then lower to recover and repeat a few times. Check with your health care professional before beginning any type of workout, especially high-intensity training.
Improve Fitness and Endurance
If you’re already in shape and want to improve your cardio fitness and endurance, HIIT is still a good choice, but you may want to ditch the incline or keep it on 1 percent to simulate outdoor conditions. A study published in the "Journal of Strength and Conditioning Research" in September 2012 led two groups of well-trained runners through a six-week HIIT program on either hills or flat surfaces. Both groups showed improvements in endurance, but gains were greater for the group on level ground.
- Journal of Sports Sciences: A 1% Treadmill Grade Most Accurately Reflects the Energetic Cost of Outdoor Running
- Gait & Posture: The Effects of Grade and Speed on Leg Muscle Activations During Walking
- American Journal of Physical Medicine and Rehabilitation: Long-Term Lifestyle Intervention With Optimized High-Intensity Interval Training Improves Body Composition, Cardiometabolic Risk, and Exercise Parameters in Patients With Abdominal Obesity
- Journal of Strength and Conditioning Research: The Effects of Uphill vs. Level-Grade High-Intensity Interval Training on VO2max, VMax, VLT and TMax in Well-Trained Distance Runners
Jennifer Arnett is a writer and editor focused on health and wellness, consumer technology and green living. She has written for several organizations and websites. Arnett holds a Bachelor of Arts in English and writing.