Add 1% of Incline to Your Treadmill Workout

Question:
I run outdoors during the summer, but when the weather turns dark and cold I generally run on a treadmill in the gym. Am I getting the same workout?

Answer:
In general, you will get a fairly comparable workout as long as you focus on your effort level (or rating of perceived exertion). There is a slight decrease in energy expenditure when running on a treadmill because of the lack of wind resistance and because the treadmill belt does propel you along a bit. To make your treadmill workout closer to outdoor exercise, simply raise the treadmill incline to 1% and you will expend as many calories as if you were walking or running on flat pavement outdoors(1).

If you are training for an outdoor running or walking event, it is fine to do some of your training on the treadmill, but try to do at least 60% of it outdoors. You will be much more prepared for the demands on your muscles and joints, the weather and the varied terrain if you run outdoors. Additionally, the treadmill doesn't have any way to simulate downhill running, which is important if you are running an event that has varied terrain. Similarly, there aren't turn on a treadmill, which is another thing your body needs to adapt to if you plan to run outside.

Treadmill Running Pros:

• No weather, temperature, or terrain issues
• Can stop anytime you need or want
• Can workout while watching tv if you like
• Smooth, cushioned surface is easier on the joints
• No concerns about personal safety

Outdoor Running Pros:

• You can run anywhere
• You get to enjoy the scenery, get fresh air, notice changing seasons, weather, and enjoy nature.
• It's generally more challenging and you expend more calories
• Possibly more motivating (must complete a distance goal)
• Most people report a greater feeling of accomplishment
• You can take new routes and see something new everyday

_{Source
A 1% treadmill grade most accurately reflects the energetic cost of outdoor running.A 1% treadmill grade most accurately reflects the energetic cost of outdoor running. Journal of Sports Science, 1996 Aug;14(4):321-7.}