Why a Runner's Flexibility is Overrated

Runner's and Muscle Flexibility

Every runner that has been to a health care provider has gone through some type of an assessment. This can be looking at the runner's flexibility, strength, balance and maybe even their running mechanics. Most of the runner's that I consult with are very concerned to learn they have a tight hip flexor, IT band or hamstrings. While there are certain circumstances when an improvement in flexibility might be helpful, flexibility with distance runners is largely overrated. 

Does Flexibility Matter? 

Flexibility is something that is very easy to measure. In the medical world, we have very simple tests that look at the flexibility of different muscles of the body. At some point, we decided to associate a lack of flexibility with whatever injury a runner was dealing with. Because something was "tight", that "tightness" was a problem. How flexible a muscle is, tells me nothing about how that runner's ability to produce force, hold a pace when fatigued, or make smart decisions in their training. 

While it would be nice if running injuries were that simple it’s just not. When it comes to injuries, there are many factors that have to be considered. We can't just isolate one variable and say this is the cause of the issue. The flexibility requirements for running are really very small. Running is a “mid-range” sport. It’s very different then baseball or gymnastics which operate closer to the end-range of our bodies joints. The video below highlights how much flexibility you actually need to run. 

Faster runner's use less joint/muscle ROM

Running is a “physiological” sport. It is purely output. How fast can you run a given distance. It’s not like basketball, football or soccer where we are dealing with changing direction or managing an implement. With that in mind, running is all about force production. How much force can you produce overtime your foot hits the ground and how long can you maintain that during a training bout or a race. Although faster running requires a little more range of motion at the knee and hip, the best runners actually go through LESS ROM when running compared to novice runners. This goes back to the idea that running is all about how you produce force, how much force you produce and how can you maintain that on race day. It's about putting more force into the ground not necessarily going through a larger range of motion. So if you are a runner who is "tight", or feels bad because they don't stretch enough, I wouldn't worry too much. 

Nathan Carlson DPT, USATF