July 13 2018
Whether you’re sticking to sidewalks or braving the sand, here’s what you need to know to avoid injury on the most common running
Growing up in New Hampshire, I ran outside in all kinds of weather: subzero temperatures, snowstorms, even a hurricane on one occasion. I realized how unwise this was after I moved away, when my father, also a runner, slipped and fell on black ice, breaking his hip. He never ran again.
Take a lesson from my dad and me, and move your runs indoors to a treadmill when winter weather makes outdoor running unsafe (or even just unpleasant). Don’t let concerns about the quality of the workout, increased injury risk or boredom stop you from making this transition. Research shows that runners can train as safely and effectively on a treadmill as they can on the roads. Making tweaks to standard outdoor run formats can make indoor running enjoyable, and exploiting certain advantages of these machines can also benefit your fitness.
Running on a treadmill is undeniably different from running on outdoor surfaces. On a treadmill, you do not move; the belt does. Your job is to repeatedly reposition your legs to avoid flying off the back. Outside, you generate forward thrust by pushing off the ground with your foot. But is treadmill running so different from outdoor running that the fitness you build indoors doesn’t fully translate to outdoor workouts and races?
Science says no. Scientists at Bowling Green State University and the University of Alabama reported recently in the Journal of Sports Rehabilitation that they found no differences in gait kinematics (measurable aspects of the legs’ movement) between overground running and running on a motorized treadmill in a group of 10 healthy women.
It’s true that heart rate and oxygen consumption are slightly lower during treadmill running than they are during overground running at the same speed, but this doesn’t mean the treadmill provides an inferior workout. A number of studies, including a 2014 experiment by Brazilian researchers, have shown that runners are able to go faster in outdoor time trials than in treadmill time trials of the same distance or duration, even though treadmill running is physiologically less stressful. What this means is that at any given running speed, you’re closer to your limit on the treadmill than you are outside.
Scientists have not compared the effects of exclusive indoor and outdoor training on outdoor running performance, but real-world evidence suggests that they are about equal. The best example comes from Christine Clark, who won the 2000 U.S. Olympic Trials women’s marathon after doing almost all of her training on a treadmill over the course of an Alaskan winter.
When winter weather forces you indoors to run, it’s important that you replicate the outdoor running experience as closely as possible. If you’re in a gym environment, there’s little you can do to control your environment, but if you’re at home, consider lowering your thermostat from the usual 72 degrees to the low 60s, which will make you feel more comfortable and improve your performance, and use a fan to recreate the evaporative cooling effect of running outside. Have fluids handy if you’re running hard or fast enough to need them.
You may have heard that you should set your treadmill belt at a 1 percent incline to match the physiological challenge of running outside on level ground, but this practice is based on the mistaken idea that heart rate limits running performance when in fact perceived effort (how hard running feels) does. Even at 0 percent, it will feel harder to match your outdoor running times indoors; raising the belt will only increase this disparity, so keep it flat unless you’re doing hill training.
Finally, because treadmills offer a softer landing than the roads do, you may find that you are more comfortable wearing a shoe that has less cushioning and a lower profile compared to your normal outdoor footwear.
Making the most of treadmill running is a matter of adjusting standard outdoor workout formats to accommodate the treadmill’s disadvantages and exploit its advantages. Here are three specific sessions to try this winter:
The biggest disadvantage of treadmill running is that it’s boring. Consequently, time passes more slowly during indoor runs—especially the slow-and-steady runs that are the necessary foundation of any effective training program. The Constant Variation Easy Run tweaks this workout to make it more fun. To do it, start by running at an easy pace (1.5–2 minutes per mile slower than your 5K race pace) at a 0 percent gradient. After 1 minute, make a small, random adjustment to your pace or incline (for example, go from 5.7 mph to 5.8 mph).
Continue making these small, random adjustments for the full planned duration of your run. The specific changes in speed or incline you make don’t matter, as long as your effort level remains low (no greater than 4 on a 1–10 scale). The point is to make time pass quicker by giving yourself something to do every 60 seconds.
Treadmills are especially conducive to hill training because they allow the runner to precisely control the incline of the belt. The tricky part is managing the recovery periods between high-intensity hill repetitions. Outside, runners typically jog back down the hill they just ascended. On a treadmill, it’s more practical to keep the slope where it is and reduce your speed to a walk to recover. Here’s an example of a hill repetitions run designed especially for the treadmill:
Another advantage of the treadmill is that it allows precise speed control, making it a great tool for practicing running at your goal pace for an upcoming event. See the chart above for race-pace workouts designed for each of the four most popular road-race distances.
As beneficial as treadmill running can be, try to avoid doing all of your winter training indoors. Treadmills offer a softer landing than the roads do, and studies indicate that the calf muscles are less active during treadmill running. For these reasons, an abrupt switch from indoor to outdoor running could leave you at risk for injuries such as shin splints and calf strains.