Sunday, September 24, 2023

Which Is Better: Treadmill Versus Outdoor Running?

Road running and treadmills offer different benefits, which vary based on the runner's abilities and seriousness.

A lot has been written about whether it is better to run outdoors or on a treadmill. Most of it is for running rookies on generic health websites and contains common-sense advice. A few articles and research papers offer more scientific guidance for advanced runners and professional athletes.

In this article, I will cover the differences relevant to various levels of runners from beginners to advanced ones.

Exhibit 1 shows important concerns for various levels of runners when choosing between treadmills and outdoor runs.

treadmill tradeoff concerns
Exhibit 1. Concerns for various levels of runners when choosing between treadmills and outdoor runs. Background image by Freepik.

My Background: Over the last 39 years, I have run 25,000 km EACH on roads and treadmills, with speeds ranging from 6 km/hour to 16 km/hour. I do have a fair bit of experience and expertise on this topic.

Treadmill Tradeoffs for Novice Runners


  • The treadmill environment is in your control.
  • You do not have to contend with heavy rains, hot weather, or bone-chilling cold. You will not face heat stroke or slip on the snow.
  • But that also removes some excuses to not run.
  • When running on treadmills, you can use the same gear throughout the year: no special socks, rain jacket, or hat is needed.


  • If you run on roads, traffic is a concern. After a long run, when you are tired, your judgement and response time to oncoming vehicular hazards may worsen.
  • Even if you run in parks, nighttime safety needs to be considered.
  • In my hometown—Mumbai, India—the main issue I have to contend with is potholes. When your leg muscles are tired during a run, it is easy to get an ankle sprain if you step into a small roadside ditch.
  • If you have travelled to an unknown location, it may not be safe to put on your shoes and head outside your hotel. You may not know the local language, safe neighbourhoods, or fickle weather. A hotel treadmill works best in such situations.
  • Have you been chased by a dog during a run?


  • Outdoors, you have to plan your water breaks well in advance (for runs longer than 10 km; you may not need water for shorter runs unless running in summer). I remember my 10-mile (16 km) run out in the New England wilderness when I found myself extremely thirsty at the turning point, with nowhere to go for water and had to walk back home.
  • In cities, carrying money for buying bottled water is a good option, which did not work one night when my long run extended beyond midnight.
  • Some people carry water bottles or bladders. If you are comfortable lugging that extra weight around, do that.

First Aid

  • If you get injured while running outdoors, it is difficult to get proper medical assistance.
  • We are talking about minor issues, not chest pain or fainting. Sometimes, I get blisters on my left foot during a long run. It is easier to stop and put on a bandage or tape if I am on a treadmill.

Surface Impact

  • Many new runners have incorrect gait and weaker running muscles. Hard and improper landings on the road can lead to common running injuries.
  • Treadmill belts are softer and absorb the running impact, which is better for preventing injuries.


  • Running on treadmills is as boring as watching paint dry or worse, watching dry paint.
  • If you are running in a loop inside a park, it can get monotonous, too. But there are levels of boredom, and treadmills surely take the first place.


  • Multi-tasking is possible only with a home treadmill if you need to keep an eye on children or the elderly.
  • Some people listen to songs or watch TV while on treadmills.
  • It is suicidal to listen with earphones when on the road, as you cannot hear any alarm sounds such as honking or car breaks. But it might be okay if you are running inside a park.
  • In the post-Covid world, I notice youngsters watching a serial on their mobiles that they rest on the treadmill panel. That is bad for the neck as it involves tilting the head forward. Luckily, most such viewers are on the treadmill only for a few minutes of their ‘cardio’ warmup.
  • I have seen a businessman get his work done while cycling on an exercycle in my gym, but I am still to see someone finishing his office work while running on a treadmill.
  • Talking of TV, when the 2011 Cricket World Cup Final Match was going on between India and Sri Lanka well past midnight, I was doing a 42 km run on my gym treadmill. I watched the final four hours on TV while running. The only problem was my treadmill faced a full mirror; so I could only view the reflection of the big TV screen. Imagine watching Captain Dhoni bat left-handed and Gambhir right-handed!

Mood Improvement

  • Unless you run in a filthy or overcrowded part of your city, road running is usually associated with fresh air, sunshine, and an improved feel-good factor.
  • Being outdoors is a mood elevator with reduced anxiety, stress, or depression.

Information Tracking

  • Most inexperienced runners overestimate their running effort—speed and distance.
  • Treadmills help you track your speed and distance covered.
  • Incidentally, the calorie count shown on most treadmills is wrong. If you are 60 kg in weight and run 8 km, you consume 480 calories, if your treadmill is set to horizontal (0% incline). Ignore what your treadmill says and use a simple rule:
Calories Consumed (in Cal) = Your Weight (in kg) x Your Distance Run (in km)

Treadmill Tradeoffs for Intermediate Runners

Muscle Strengthening

  • Roads are often banked (tilted, for rainwater drainage) and have slight imperfections. Your ankle muscles have to work a little extra when you run on roads, which strengthens them and helps in an actual race.
  • If you have done skiing or ice skating, you know how hard it is on your ankles the first time. But with time, you don’t even notice it as your ankle muscles get stronger.

Effort Index

  • It has been proven that the amount of oxygen consumed during exercise—VO2—is the same for a speed whether you are running on the road or treadmill. So both involve the same aerobic effort. This is true below a certain high speed, which is explained later.
  • Some people think that since the treadmill belt moves under you even when you are airborne, a treadmill run will involve less effort than running on the road. Over the years, many people have argued with me about this and I understand that it is hard to wrap your head around the concept. However, physicists call it a problem of relative motion in a moving frame of reference. Think of it this way: If your treadmill were a very long and wide belt stretching hundreds of metres in all directions around you and moving backwards, how would you possibly know that you are jogging on a treadmill and not a road?
  • Even running at an incline on a treadmill consumes the same VO2 as running on a road with an identical incline—identical aerobic effort.

Uphill Running

  • Uphill runs are great conditioning exercises with less impact compared to running on flat roads.
  • They can simulate speedwork if done at lesser inclines. At steeper slopes, the running form changes and does not mimic flat-road running.
  • If you live in an area that is mostly flat, treadmills are your only option.
  • After an outdoor uphill run, you have to trudge back downhill, which can hurt the knees and front muscles around your shin (anterior tibialis). Treadmills can bypass this need.
  • Treadmills allow you precise adjustments of inclines.


Biomechanical patterns do not change whether you run on a treadmill or on the road. So treadmill running can train your brain in the same neuromuscular sequences that road running does.

Recoil Energy

  • Road asphalt and concrete are harder than treadmill belt rubber. Road surfaces benefit good runners as their leg muscles, tendons, and ligaments stretch, absorb, and store the impact energy of foot landing, which is given back in recoil during the bounce-back stage of the step.
  • You may have noticed that sometimes it is harder to run slower, which is because of this lost recoil energy.

Treadmill Tradeoffs for Advanced Runners

Air Resistance

  • The old belief is adding a 1% incline on treadmills simulates outdoor running due to added air resistance. But it was based on a study that was done on runs faster than 11.5 km/hour.
  • It turns out that only at speeds above 14 km/hour, outdoor running adds significant air resistance. A treadmill can simulate that if you add a 1% incline to the same speed. In other words, running at 14 km/hour on the road is as hard as running at 14 km/hour on a treadmill with a 1% incline.
  • At higher speeds, you will face even more air resistance when running outdoors but remember that air resistance increases with the square of running speed. Forty per cent higher speed would double the air resistance.
  • For running on a treadmill at 19.5 km/hour—40% faster than 14 km/hour, you would need a 2% incline setting on the treadmill. But most of us are unlikely to hit those speeds, leave alone sustain them.
  • Such adjustment is needed at lower speeds, too. As speeds fall below 14 km/hour, the air drag drops rapidly. For the speed of 10 km/hour, a 0.5% treadmill incline might be appropriate. But most treadmills don’t have fractional percentage incline settings.

Downhill Running

  • Most treadmills don’t allow downhill running, especially a down-gradient of more than 3% (3 metres decline every hundred metres).
  • In a race with hilly terrain, you will need strong downhill running ability and your anterior tibialis muscles (around your shin) should be strong enough to cushion the impacts. Without that strength, your thighs and knees take the hammering, tire out, and prevent you from peak performance.
  • One option some coaches suggest is artificially lifting the rear legs of a treadmill with block placement underneath the treadmill’s rear shoes. I feel that can be dangerous at those high speeds if the treadmill becomes unstable or topples. It is best to train for downhill on actual hills.

Lateral Agility

  • Treadmill running does not involve turning left or right. For a good runner, lateral agility is important as many courses have bends or even sharp turns that need to be navigated without losing speed.
  • On a treadmill, you run in a straight line and the muscles that control your sideways movement during a run stay weaker.

Event Specificity

If you are taking part in a trail run, treadmills simply cannot help you beyond basic fitness; you will need to train on trails.


  • The main difference between a treadmill and outdoor runs is what very few talk about: the former is a constant speed run and the latter is usually a constant perceived effort one.
  • When we run outdoors, we may run hard or easy depending on the feel. We use phrases like ‘catching breath’, ‘getting a second wind’, and ‘easing throttle’. As good runners, we do so instinctively, and outdoor runs can help our bodies hone that pacing ability, which is crucial in a race.
  • Treadmills don’t adjust their speeds automatically based on our moment-by-moment exertion feelings. Continuously changing the treadmill speed manually during a run is not a viable option.

Mind Control

  • In racing, and to a lesser extent in running, mind control is important.
  • On a treadmill, you may set goals based on the displayed numbers (“I will run hard for the next 800 meters” or “…5 minutes”).
  • In an outdoor race, you cannot check your watch all the time. So you will set mental targets based on landmarks (“I will run hard till the next bend”, or “…till the top of the hill”, etc).
  • Since the two types of runs train your mind on different parameters, they are not equivalent.

Did I miss out on any other factor in the above list? Please mention that in the comments below.


  • Novice runners can do 100% of their running on treadmills if required. They have more to benefit from the controlled environment of indoor treadmills.
  • Intermediate runners should not do more than 70% of their running on treadmills. They should add some ‘road feel’ and muscle-strengthening by running outdoors.
  • Advanced runners should not do more than 40% of their running on treadmills. They should treat treadmill runs almost like cross-training. If they run twice a day, they can do their evening run on a treadmill for safety reasons. They should set the treadmill at an incline of 1%–2%, as appropriate, to simulate the same pace.
  • When running on a treadmill, always wear the safety harness: this is a clip with an attached rope that is connected to the Emergency Stoppage switch on the treadmill. You should attach the clip to your running top or shorts. If you trip while running, the rope gets yanked, which stops the treadmill immediately. Sadly, in my entire life, I have never seen anyone wear it other than me. While searching for images for this article, I went through hundreds of photos of runners on treadmills and none of them had worn it either.
  • Treadmills are great for runners coming off an injury, as they put less impact on the body.
  • Finally, it is better to run either way than not run at all.

To Read More

First Published on: 24th July 2023
Image Credit: RUN 4 FFWPU on Pexels


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