It’s a personal preference when it comes to running on a treadmill or concrete for runners. It is for different reasons each of them chooses either one of them or both of them. Some prefer accuracy, while some love the scenic view.
Few individuals feel running on a treadmill is monotonous and boring, but at the same time, some others claim that a treadmill workout is structured and motivating as they can check their progress in numbers.
While running on concrete pavement offers an excellent exterior view, you cannot say that it is always possible to run outdoors due to various climatic conditions.
Also, when you are running outdoors, you should focus on obstacles on your way that somehow intrudes with your peace of mind.
One of them cannot be termed as right or wrong, but it can be said that each of the settings has a different effect on your body, and you need to choose based on why you are running.
Both methods have their benefits and risks, which you need to consider thoroughly before deciding.
You might be practicing running for cardio benefits or training for a race. Your end goal plays a major role as they have varying outcomes on your muscles, bones, and health.
Here, we discuss every possibility in detail to give you a better insight into what you will deal with by choosing each option.
Which surface is best, according to research?
A softer surface offers better shock absorption than a rock-solid surface, meaning reduced chances of injury.
The greater impact force resulting from the hard surface has a higher effect on your knees, leading to immediate or long-term injuries caused due to overuse.
You can find a lot of research based on a hard and soft surface for the suitability of running. A soft surface is more preferable for reducing physiological stress.
The Journal of Sports Physiology and Performance says that the treadmill’s average shock absorption rate is running is 71%, whereas it is 0% on concrete.  Though ultra-cushioned shoes and body mechanics influence shock absorption, the running surface still has a considerable impact.
Another study published in 2008 by the Journal Foot and Ankle International assessed 291 elite athletes who developed tendinopathy based on their running on different surfaces.  Among them, 56.6% of runners reported Achilles tendon, and 46.4% complained of knee pain.
Surprisingly the results showed that the risk of tendinopathy is lesser for those who ran on concrete than on the soft surface. However, an article published in the British Journal of Sports Medicine found no significant relation between injury rate and the running surface. 
Advantages of running on concrete
You don’t need to buy any special equipment for running on concrete, and it is a space readily available for people living in a city. The sidewalks and pavements are made of concrete and meant to walk safely even in high traffic areas.
The advantage of these sidewalks is that they keep you away from traffic and provide you with a flat and smooth surface to walk on. According to research, if you are not running too fast, according to research, the effect of the terrain is negligible in terms of impact on joints and muscles.
Unlike other outdoor surfaces such as grass, where the pits, broken glass, rocks, and rough exterior are not visible to the naked eye, you can see what is on concrete.
You also get to step steadily on the concrete as you move forward to sand or wetland where your step sinks and you lose energy.
Disadvantages of running on concrete
Concrete is composed of cement which is hard and does not help in any impact absorption. Meaning the runner gets to absorb the maximum shock, which exerts more and more stress on each foot strike that is impactful to your knee.
Advantages of running on a treadmill
Treadmills come with a moving belt, which is specially designed to absorb the impact on your knees. They are equipped with cushioning at several places that act as shock absorbers which keeps your knees stress-free by putting low impact on them.
You can either run on a flat surface or on an incline-controlled surface which allows you to mimic different terrains such as uphill or downhill. Even if you have knee injuries, you can still run on a treadmill using the right posture and incline suitable for recovery.
However, low-end models might not have most of these features along with proper cushioning. So, take care that you do consider the cushioning options and the incline facilities when you purchase to enjoy the benefits of a treadmill fully.
Disadvantages of running on a treadmill
Along with excellent benefits, there are also some risks involved while running on a treadmill. Most of them are avoidable using a few tips and tricks due to the few mistakes users make while working on a treadmill.
Maintaining a proper form from the start to the end is not possible for all runners, and it is one of the major reasons for deteriorating knee health. When runners bounce more than they should while running or pick up slower pace than required, it reduces efficiency and more stress.
When you’re running on the same spot, it is easy to lose focus on maintaining your speed. When this happens, you might slip from the treadmill and be thrown behind without any warning. So, you need to be mindful of your speed and work out to avoid such mishaps.
As there will be no natural wind around, treadmill runners sweat heavily, requiring a fan to cool you during the workout. Treadmill runners try to overstride by stretching their legs too far ahead, causing greater strain on their knees and heel.
Many treadmill runners use their toes during running, which puts significant strain on your knees with each stride you take, leading to pain when they walk. Walking on a 0% incline on a treadmill is not equal to the flat ground but with slight downhill compared to outdoors.
People tend to land with their foot in front of their body due to the action of the tread belt that forces a person forward. Research states that this motion can collide with their locked knees which can result in a knee injury.
How to run safely on concrete?
When you run at a moderate pace on concrete, it does not impact your knees. Also, manage your speed properly when you face obstacles such as curbs, traffic while crossing, and pedestrians as the sudden speed changes are stressful to your knees.
Wear well-cushioned shoes that are capable of absorbing shock, and make sure to replace them often.
How to run safely on a treadmill?
Treadmills offer a confined space to run, meaning there are high chances of you to over-step, under-step, or side-step off the running area if you are not careful enough, which can lead to falls and injury. So always make use of handrails or stabilizers to keep yourself safe.
Make sure your speed matches with the speed of the machine properly; otherwise, adjusted gently, right increasing or decreasing the speed. If you are using a treadmill to alleviate your knee pain, but if it is getting worse, then stop running and consult your physician for further instructions.
When you set the treadmills incline to +1 to 3%, it replicates flat ground and goes easy on your knees as it replicates natural motion.
A running surface does affect your performance and has different advantages and disadvantages based on several factors. It is a combination of personal preference and your fitness goals that can decide the best option for your running.
If your goal is to achieve cardiovascular benefits, then a treadmill is the best option. You can run without worrying about the climatic conditions or other obstacles such as traffic. Since these machines are specifically designed for running and walking, they exert less stress on your knees.
However, if you’re training for a race, it would be beneficial to run outside. If not totally, at least for a part of your training to get you fully prepared for the race. While these are simple examples, you might have many other factors to consider before choosing what is best for you.