This is a post by Dr. Dustin Lee PT, DPT
There is a lot more to running than meets the eye. In fact, if you break down the running motion by looking at specific movements and forces, then you will begin to understand how amazing our bodies are at adapting to dynamic activities. Dynamic activities are those that require the body to react constantly to an external force. Here are a few examples of external forces that your body must react to while running:
1. Your foot contacting the ground on level, uphill, downhill, slanted surfaces, etc.
2. Navigating rough terrain and trails
3. Being bumped into or tripped at the start of a race.
The body’s musculoskeletal (muscle and bone) and neuromuscular (nerve and muscle) systems are two systems that are responsible for producing and reacting to forces. When your foot contacts the ground, a force is exerted by the ground onto the body, and the body onto the ground, via gravity and momentum. Our muscles and tendons (and ligaments in some instances) must be able to counteract this external force by producing their own force internally. Ideally, the force produced by the body internally will equal, or be capable of exceeding, the external forces that act on the body while running. This must happen rapidly since the foot is on the ground for only milliseconds for each step. When the external forces are greater than the internal forces, we start to see tissue break down and microscopic changes common in overuse injuries.
There are two peaks that display how much external force is acting on the body when considering vertical (up and down) motion. The initial peak is called the impact peak, and it is a pivotal point in the running motion where many overuse injuries are typically seen. The second peak, occurring as our leg travels underneath our body, is called the active peak. This peak is a larger force than the impact peak force and is another critical area to observe while watching someone run to help with injury prevention. For our purposes, we will only be covering ways to change impact peak force. Lessening the impact peak will also contribute to reduction of the active peak, and many of the same running form tips and interventions are utilized to reduce both peaks.
Understanding how you can control the amount of impact peak and active peak force can be helpful for injury prevention, recovering from an injury or even just learning how to be a more efficient runner.
The impact peak force is increased with the three factors listed below, and a helpful hint is provided to help you take control of your run and reduce these forces.
1. Running downhill
Most people tend to lean backward and lengthen their strides as they run down. This is problematic because this type of running stride increases the “braking force” acting on the body. Simply, you are preventing gravity from taking you down the hill faster, even though you feel like you are flying!
The fix: Lean slightly forward from the hips and ankles, and make flat foot contact with the ground underneath your body.
2. Slower step rate
There is a range of step rates (number of steps per minute) that are discussed in the running community. Have you ever read that 180 steps per minute is ideal if you want good running form? There is some truth to this; however, it is not “all-or-none,” meaning this ideal number will vary for everyone. The literature states that an efficient step rate allows the gluteal musculature to contract more effectively, and it reduces the load on the quadriceps and hamstrings2. Say goodbye to that pesky knee pain! Changing step rate may not be acceptable for everyone; however, if you are experiencing knee pain, it might be worth a try.
The fix: Count the number of steps you are taking per minute and try increasing this number by seven to 10 percent. For example, if I counted 84 steps with my right foot in one minute, I then multiply this number by two to find my step rate of 168. Then my new goal step rate is in the range of 179-184 steps/minute.
3. Pronounced heel strike pattern
I am sure that I am going to open a can of worms with this statement, so let’s get something straight – I am a proponent of all foot strike patterns…as long as the pattern matches how fast you are running and you are utilizing the strike correctly. Having a pronounced heel strike when contacting the ground is typically seen with angles between the foot and ground >15 degrees. This goes hand in hand with slower step rates, over-striding and even running downhill. The knee and lower leg are usually in a more straightened, or extended, position when contacting the ground. This increases the load through the body and stiffness through the leg. I’ll say it again: there is nothing wrong with a heel strike pattern unless utilized incorrectly.
The fix: Increase your step rate using the formula above, and make sure that your foot is landing closer to the center of your body. You may even play around with running at a slower pace to practice foot contact position.
Interested in learning more about the dynamic process of running, how to prevent injury and how to improve your running form/efficiency? Make sure to reach out to a qualified physical therapist that specializes in runners or even a running coach. These professionals can help you understand the factors that are causing breakdown in your running form and get you back to happy and healthy training.
Lastly, Precision Performance & Physical Therapy offers performance assessments, where we discuss your running form, training plan, shoe wear, past injuries and how to address each of these to run more efficiently, recover from an injury or prevent future injury while you are training. Contact us today to schedule your appointment!
Thanks for reading!
Dr. Dustin Lee, PT, DPT
1. Heiderscheit, B. Orthopedic Management of the Runner, Cyclist, and Swimmer: Biomechanics of Running. Orthopedic Section, APTA, Inc. Orthopedic Section Course.
2. Lenhart, R.L., Thelen, D.G., Wille, C.M., Chumanov, E. S., & Heiderscheit, B.C. (2014). Increasing Running Step Rate Reduces Patellofemoral Joint Forces. Medicine & Science in Sports & Exercise, 46(3), 557-564.