- A University of Colorado study found that the angle at which someone leans forward while running affects their chance of injury.
- When people run, their feet touch the ground more if they lean forward.
- Overuse of the hips, knees and feet can be caused by leaning forward.
Running is often seen as an activity that takes place primarily from the waist. Researchers at the University of Colorado, Denver have found that runners’ injuries and running style can be affected by their torso angle.
Running too far forward can increase your chances of getting overused injuries.
The study appears in Human Movement Science. It examines how runner’s trunkflexion affects their ability to hold their torso while running. Researchers found that even tiny changes in trunk flexion could have a profound impact on motion or “kinematics” of lower limbs, and how hard they run.
Although running does not involve the trunk, arms and head, 68% of the body’s mass is made up of these parts.
Researchers devised an experiment to test the effect of trunk flexion on runners to determine if they could hold their torsos at certain angles while still being able to run.
“We had to create a way,” says lead author Anna Warrener, Ph.D., “in which we could reasonably force someone into a forward lean that didn’t make them so uncomfortable that they changed everything about their gait.”
Researchers found that treadmill runners leaned forward to avoid hitting a lightweight plastic dowel. The dowel’s position was more important than its height. This caused runners to dunk less and their trunk flexion increased. The researchers dropped the dowel and the runners lean forward as the researchers lower it.
Researchers recruited runners who were healthy and had no injuries. They ranged in age from 18-23 years. Each participant ran short 15 second trials at 3 m/s. The researchers requested that they perform trials at the preferred trunkflexion angle and tilting forward at the following angles: 10, 20, or 30 degrees.
Dr. Warrener reports that they thought that the more you lean forward, the greater the need for your leg to extend to prevent your body mass falling outside of the support area. Overstride frequency and stride frequency would increase.
The results were surprising, however. Dr. Warrener recalls that the relationship between strike frequency (and stride length) was surprising to them. The reverse was true. Stride length decreased and stride rate rose.”
The average stride length of a runner decreased by 13 centimeters. However, stride frequency increased from 86.3 to 92.8 steps per minute.
When runners lean forward, overstride relative the hip — when the foot lands too far in front of the hip — was 28% higher.
Sarah Pelc Graca, Strong’s trainer, explained to Medical News Today that overstriding can lead to patellofemoral pain syndrome and iliotibial bands syndrome.
Dr. Warrener suspects that runners overstride due to a reduction in the time their feet spend in the air between steps if they run with their heads up. This airtime allows for less forward travel, which means that runners take shorter steps.
Dr. MNT spoke to Bert Mandelbaum, a sports medicine specialist and ortho surgeon at Cedars-Sinai Kerlan-Jobe Institute, Los Angeles, and author of The Win Within. Capturing Your Victorious Spirit.
Dr. Mandelbaum stated that running is about efficiency and energy dissipation.
He stated that the more efficient we are and the lower our ability to dissipate energie, the greater the proclivity we have to create an overuse situation or stress injury.
Dr. Warrener says that the shorter airtime the researchers observed in the study led to an overall increase of energy use. “The act swinging your leg is just as expensive as running. Higher locomotor costs may be associated with swinging your leg faster when you lean forward.
Researchers discovered that runners with higher trunk flexion were more likely to sustain injuries.
Running forward causes runners to run harder by leaning more forward. As runners ran, they had a more flexed hip joint and a bent knee joint.
Optimizing how is run
Dr. Mandelbaum stated that it was important to not underestimate the impact of modifiable factors. He said that trunk flexion is only one of many, and that there are many more, including diet and proper running shoes. “Your weakest link is your strongest.”
Dr. Mandelbaum advised everyday runners to experiment with different running positions to find the best one that feels good, allows them to move freely, and rewards them for it.
Dr. Mandelbaum said that runners feel almost like they are floating when they find their “sweet spot”.