When it comes to exercise, everyone wants to know what is the most effective form of __ ? If you are a power lifter you're probably interested in the high-bar vs low-bar back squat debate. Fitness enthusiasts all over debate HIIT versus long training sessions with plenty of recovery. In the world of running, the argument becomes, should I hit the trails? Or is it better to run on a treadmill?
Like any form of activity, there are pros and cons to each. There are times when treadmills can be used to create a positive training stimulus, and there are times when a runner should be outdoors hitting the trails. Before we can discuss the effectiveness of running on a treadmill versus running outside; however, we must first discuss the proper mechanics of running.
Why should a runner think about their mechanics?
Running on any surface produces forces that travel through the lower limb and should be absorbed by the muscles of the legs. When running mechanics start to break down, these forces transfer from the muscles to the joints and can result in chronic issues such as tendonitis. To avoid chronic break down of either muscles or joints, a runner should focus on proper running mechanics before putting in a high volume of miles.
How running is developed
By the time we are a year old, must of us have taught ourselves how to walk. Sure, mom and dad help out by holding our hands so we can maintain balance and remain standing, but no one informs a baby that they need to put one foot in front of the other, maintain their center of gravity in the split stance, and swing their arms to counterbalance what their legs are doing. This is something that just naturally comes to a toddler learning to walk.
The same is true of when we start to run. We start performing this activity from a very young age without any formal instruction. Running is a natural human movement. But if you compare a video of how you ran as a toddler and how you run today, the movement of your legs, torso, and arms would be completely different. Aside from having much longer limbs, as we grow older, our running form tends to change drastically due to tight hips (from sitting too much) and a weak torso (often from lack of training); often, this change is for the worse.
For those individuals lucky enough to receive coaching on training form, you have probably saved yourself from chronic issues such as runner's knee or plantar fasciitis. The rest of the running population just considers these to be part of the norm that they must learn to train around, but it doesn't have to be that way. If you utilize proper running form, whether you're on a treadmill or running outside, you can maximize the effectiveness of any running workout.
What is the proper way to run?
Brian Mackenzie, founder of CrossFit Endurance and author of "Power, Speed, Endurance," breaks running down into 3 easy phases: the fall, the pull, and the shift (p. 36-38). To run properly, one must lean their torso forward just far enough that their center of gravity is moved forward, and they begin to fall. Doing this will propel the body forward, using gravity as the driving factor and provider of energy for the movement.
Following the fall, one leg will be outstretched to catch the body. This, again, is our natural tendency. When the foot lands on the ground, however, things get wonky. To effectively maintain forward momentum, the foot should be landing under the torso or hips, and the runner should be landing somewhere between mid-foot and the ball of the foot (the actual placement depends on your running speed). From here, the hamstring and glutes are contracted to "pull" the leg backward as the torso passes in falling toward the next step.
This is where most runner's default. Because of tightness in the hips, and the shape of certain cushioned shoes, runner's feel, it is ok to land on the heel of the foot. This break down in form leads to a sudden impact of forces through the ankle and knee joint. When a runner can stay on the midfoot, the forces are gradually introduced to the lower limb allowing for proper distribution before transitioning into the support phase.
The final phase is shifting support. The runner now extends the opposite leg, keeping arms relaxed and moving front to back (never side to side), as they continue to fall and cycle through these 3 phases.
Figure 1. Forces during heel strike vs. midfoot running
Will running form change when running on a treadmill vs. running outside?
Yes. A runner's form should have small variations depending on the surface they are running on and the speed at which they are running. When running on a treadmill, the stride length will be shorter, and the lead foot will land more under the hip; when outside, the stride tends to be slightly longer with the foot placement more under the torso. These slight changes, along with variations in ankle and knee flexion, are the reasons why running on a treadmill and running outside, are useful for different forms of training.
Things to Consider When Running on the Treadmill
Running on a treadmill allows a runner to control many different aspects of their workout. This control can aid or hinder the runner depending on their training goals. Here are a few things to consider when setting up for a treadmill workout:
- Increased Leg Turnover
As noted above, running on a treadmill causes a runners' stride to decrease in length, this can be attributed to the movement of the belt. Once a treadmill is turned on, the ground under a runner's feet is continuously moving. When the runner extends their lead leg and places the foot, it is already moving backward with the belt of the treadmill. This decreased stride length forces a runner to increase leg turnover to keep up with the speed they have set.
- Softer Surface for Less Soft Tissue Hardening
The belt of the treadmill is suspended off the ground, to allow for the belt to pass around the running surface. This suspension creates a giving surface that will compress slightly as the runner's foot hits the treadmill, absorbing some of the downward force created by gravity pulling the runner down and the runner striking the leg into the ground. By absorbing some of the force, the treadmill reduces the tension and forces acting upon the soft tissue of the lower leg.
- Less Vertical Travel and Knee Extension
When watching a runner on the treadmill from the side, one might notice that the runner's body does not bounce up and down a considerable amount. This bouncing is referred to as vertical travel and it is reduced while on a treadmill since the amount of forces being exchanged between the body and the belt are dampened. With the increased turnover rate and lower vertical travel, a runner's supporting leg does not pass as far behind the torso as you would see while running outside. This shortened range of motion results in less knee extension and hamstring recruitment while running on a treadmill.
- Consistent Tempo
The belt of a treadmill will travel at a predetermined speed. Unless the runner manually decreases or increases this speed, they will maintain the same tempo throughout their run.
Things to Consider When Running Outside
There are less controlled factors when running outside, which may benefit a runner depending on their training phase. As compared to running on a treadmill, a runner who is training outside needs to have a plan for maintaining pace and understand the surface they are running on (harder surfaces will increase forces acting on the lower limb). They must take into consideration the state their body is in, are they fresh or battling some injuries? And what the environment around them looks like. Here we discuss the top considerations when running outside.
- Muscle and Mental Conditioning
When running outside the large muscles of the legs are recruited at a higher rate since the body is now responsible for moving the body along the ground. Without an ever-rotating belt beneath the runner's feet, the body must expend more energy to maintain speed and movement. This increased force exertion also challenges the brain to keep the body performing at a higher level.
- Weather Acclimation
Running outside exposes the runner to any natural elements that may be present. A runner must take into consideration the temperature, humidity, and weather conditions since a change in any of these will require the body to respond in various ways. As temperature and humidity increase, sweat rate increases, and more water is lost. Running in the wind will require more energy than running with the wind. The elements provide another training level for the runner to accommodate to.
- Sun Exposure for Vitamin D
Vitamin D is necessary for the body to absorb phosphorous and calcium (which is responsible for healthy bone growth and muscular contraction) and according to a study performed by Rathish Nair and Arun Maseeh, 50% of the population are deficient in Vitamin D. The main contributing factor for this is sun exposure, which is required for vitamin D production. Running outside will increase sun exposure and the body's ability to produce this crucial vitamin to help keep muscles and bone health.
When is it more effective to run on the treadmill?
Running on the treadmill has a place in any training regime. As discussed, a treadmill can reduce forces on the soft tissue and joints of the lower leg and force a runner to maintain a consistent tempo. These two factors make running on the treadmill effective for a runner coming back from an injury or who needs to practice tempo work.
When is it more effective to run outside?
Being outside, in general, has many health benefits- from increased vitamin D production to reduce stress levels from exposure to natural elements; but running outside can increase these benefits as well as be effective for specific training goals. Running outside is effective in building mental integrity and lower leg strength. The lack of a moving ground will recruit the hamstring and glutes at a higher rate than running on a treadmill, and this increase in exertion will also tax the cardiovascular system at a higher level.
Aside from the increased physical benefits, running outside is highly effective in preparing a runner to face race conditions. If you are training for a marathon, Spartan, or any outdoor race, you will be faced with the natural elements. Training outside will help prepare the body and the mind to face these challenges.
There's no doubt that engaging in cardiovascular training will have a positive effect on an individuals' health. If you can participate in a regular running routine, you have placed yourself above the average human who sits and waits for their health to improve on its own.
To gain the full spectrum of benefits running has to offer, consider utilizing both training environments. Running on a treadmill and running outside are both effective forms of aerobic training. Running on a treadmill is more effective when working on tempo since the speed of the belt cannot be easily changed; while getting ready for race day should be done outside facing the elements. Running outside is also more effective in building the cardiovascular system and strength of the lower limbs, but running on a treadmill can be used as a recovery tool to get miles in without excessive pounding on the joints.
To determine what is right for you, layout your training goals, and choose the implement that aligns with what you want to achieve. Neither environment is right or wrong, but choosing the setting that suits your needs will be the most effective form of training you can engage in.
Mackenzie, B. (2012). Power, speed, endurance: A skill-based approach to endurance training.
USA: Victory Belt Publishing Inc.
Nair, R., & Maseeh, A. (2012 Apr). Vitamin D: The "sunshine" vitamin. Journal of Pharmacology
& Pharmacotherapeutics, 3(2). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/
CrossFit Journal on Basics of Running by Brian Mackenzie
Article on Barefoot Running (retrieved ground reactions force graph from here)
CrossFit article on biomechanics of running (used for running photo)