Ask the Expert: Indoor vs. Outdoor Running

Treadmill image via Shutterstock.

Boston runners are used to running in harsh temperatures: brutal heat during the summer, and bitter cold and snow during the winter. When it comes to days with extreme heat or cold, or late nights, we often find ourselves turning to the treadmill. But can the treadmill help you build the same endurance as running outside? We asked Sarah Walker, a running coach at the Boston Running Center and a competitive distance runner, whether hopping on a treadmill is just as good as a run along the Esplanade.

Is running on the treadmill just as good for me as running outside?

I prefer that my runners to run outdoors whenever possible. Only under extreme conditions like heat waves, blizzards, or discomfort about running in the dark do I prefer a treadmill. Here’s why: Running indoors requires less energy expenditure because the belt is moving for you, there is flat terrain for the entirety of your run, and you’ll experience no wind or air resistance. On a treadmill, your stride mechanics also differ slightly because your hamstring, which helps to provide the backwards pull of the leg when you run outdoors, is assisted by the belt on a treadmill. So running on a treadmill is not 100 percent the same as running outside. If the choice is running on a treadmill or nothing, I prefer treadmill running, but there’s a transition period when you go from only treadmill running to outdoor running which you need to remember.

What can runners do to ease the transition from treadmill to outdoor running?

I suggest using a one percent grade when running on the treadmill to emulate a flat surface outside, which will help you transition. In addition, I believe that running on a treadmill prevents you from establishing an innate awareness of your pace, since the machine paces you. I want all of my runners to be able to run outdoors and have a good sense of what pace they are running, so when running on a treadmill, I suggest covering up the pace and distance with a towel. I have my runners attempt to run based on feel as opposed to being accustomed to running at only seven mph for 30 minutes, for example. 

What should I do if I’m stuck on a treadmill because of the weather?

If you want to be a better distance runner, you want to teach your body to run at an easy pace for an extended period of time. If you have no other alternative and can only run on the treadmill, I suggest covering up the pace and distance with a towel, setting the incline to 1 percent, and running at what you perceive to be an easy pace for a long period of time. The duration of the run should depend on your fitness level, training history, and goals.

I don’t ever recommend speed workouts on the treadmill, though. Contrary to popular belief, I am confident that we are faster when we run outdoors. But one way to tap into a faster gear if you have to work out on a treadmill is to play around with incline. Running on an incline can help to strengthen your legs. I suggest starting with an incline of four to six percent for 30 to 60 seconds at a time. When running outdoors uphill, your speed is not constant as the incline increases, so be prepared to slow your speed on a treadmill by several tenths of a mile if you are not accustomed to running hills or on incline. If you are not new to hills, try running at the same speed or slightly faster uphill. To work on speed, you can also include one to three minute moderate bursts of speed within a treadmill run.

So what’s the bottom line here? When should we ditch the treadmill and head outside?

The bottom line is that every runner is unique. Some runners love the heat and some love the cold. We shouldn’t attempt to fight the weather, but we can adjust. Typically, it takes up to two weeks of daily exposure to either the cold or heat for us to begin to adapt our workouts. One way to adapt is to split your run into two parts where some of the run is outdoors and some is indoors. This breakdown certainly depends on how extreme the conditions are. Also, if you are unable to run outdoors or are uncomfortable with running outdoors and do not have access to a treadmill, aquajogging, or jogging in a pool, is a great way to maintain cardiovascular fitness. Basically, running on a treadmill is better than no workout at all, but it’s best to run outside when you can.