By Dr. Aaron Case BSc, DC (March 2010)
Why can some non-runners get off the couch and successfully complete the 10K Vancouver Sun Run without much training whereas some runners have difficulty completing the distance?
Other than genetics and previous sport participation, the answer may be that the non-runners have the advantage of increased stiffness. The purpose of this article is to help make you a faster, more efficient runner by explaining the benefits and drawbacks of stiffness in your legs and core, as well as some of the factors that influence stiffness.
First of all, I’d like to define stiffness:
Stiffness in a runner: The ability to quickly contract or fire a muscle. This stiffens the leg and allows elastic energy to be stored. Elastic energy allows you to push off the ground more efficiently. For example, think of a hard bouncy ball (more spring = more bounce and distance) vs. a softer ball (less spring = less bounce and distance).
My interest about stiffness started when I noticed that many experienced and faster runners often stood around after a run and didn’t stretch. I realized that they were using their stiffness to enhance their performance. I then asked myself: How did these experienced runners stay injury-free without stretching? Doesn’t static stretching generally prevent injury? Through research, I learned the answer was not necessarily. For example, a meta-analysis (highest level of research) of 361 published research papers conducted over 36 years on the topic of “Impact of Stretching on Sports Injury Risk” concludes: “There is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes.” (Thacker et al., March 2004).
So, I changed my own training as an experiment. I stopped doing held (static) stretching. Although you can be flexible and stiff at the same time, the more flexible you are, the more muscle activation is required to create stiffness and thus, excessive flexibility can decrease performance. Since my goal is to run faster, I decided to stop trying to improve my flexibility with static stretching.
I began training for increased stiffness using the methods I mention below. The results of my experiment agreed with the research. My speed and fitness peaked by the end of the year. I had a personal best in the Victoria marathon (2:42:03) without increasing my mileage. This experiment taught me that stiffness can be trained for an increase in performance without increasing the risk for injury.
Benefits of Stiffness to a Runner
- Increased speed and efficiency
- Research suggests that increase stiffness may reduce soft tissue and joint injuries by not allowing the joints, muscles, tendons and ligaments to go into repetitive ranges of motion that can cause overuse injury (Granata et al., 2001; Williams et al., 2003, 2001)
The Drawbacks of Stiffness to a Runner
- Stiffness creates extra force (ground reaction) when the foot hits the ground. This extra force may (more research is required) increase the likelihood of stress fractures from overuse. A precautionary measure would be to add extra Calcium (and Magnesium) and Vitamin D in your diet/supplements as well as gradually progress in your running program if you decide to increase your stiffness or reduce your static stretching.
Ways to Increase your Stiffness
Run on softer surfaces: Our legs anticipate the softer surface and we subconsciously stiffen our muscles and core to prevent injury and create/train the stability BEFORE we even land.
- Example: Many of the best runners in the world do most of their training in the mountains, hills, beaches, tracks and other soft surfaces before they start winning road races.
Shorten your stride by increasing your leg turnover (cadence): In general, those with a shorter stride are more efficient (i.e. stiffer) when running at the same speed. The magic number for leg turnover is approximately 180 steps per minute (3 steps/second) regardless of you height, gender and running speed (some individual variations).
- Example: From 3 km to the marathon, elite runners are all very close to a cadence of 180 regardless of height, gender or finishing place/time.
Dynamic stretching: Helps to maintain or increase flexibility without reducing stiffness.
- Example: Some examples of dynamic stretches for runners such as ABCs (legs swings, butt kicks, horse stomps) can be found here.
Plyometric drills/exercises: Plyometrics is the activity of rapid alternation of lengthening and shortening of specific muscle groups while resistance (body weight) is continuously being applied to them — basically, dynamic stretching with a load. Examples include: hopping, skipping, jumping, running fast, strides, ABC drills, fast feet, cross-overs, bounding, jumping squats and lunges improve your reaction time, enhance synergistic muscle firing, and create more stiffness. Some descriptive examples can be found here.
- Example: Competitive runners have been shown to improve their 5 km times (2-4%) by LOWERING their mileage and in place of a previous run, doing plyometrics and drills instead (J. Appl. Physiol., 1999).
Core training – torsional stiffness: Core strength allows for an efficient transfer of energy between the lower and upper body preventing excessive twisting.
- Example: Planks on a single leg and/or arm are a great way to train the core to specifically maintain upright, postural and counter-torque forces necessary to maintain cadence and good running form. Click here for exercises and a video demonstration.
Summary
Based on research and my personal experiment, it appears that when runners achieve an optimal level of stiffness, their running performance benefits.
Like a hard, bouncy ball or stiff spring, when your legs hit the ground, stiffness allows for better energy transfer and return.
When runners experience too little or too much stiffness it can create problems. For instance, there is some evidence that increased stiffness (and/or too little flexibility) may be related to bone injuries and decreased stiffness (and/or too much flexibility) may be associated with soft tissue injuries.Finding your optimal level of stiffness requires you to conduct your own experiment using the methods mentioned above.
Nevertheless, there are many runners who do benefit from regular static stretching and should not stop what is working for them. For these runners, if you interested in increasing your stiffness, I suggest that you gradually add some of the methods mentioned above (2-3 x per week) to your usual static stretching routine. You should to see performance results in as little as 4-6 weeks.
Finally, please remember that if someone in sweatpants and a headband from the 1980s flies by you during the Sun Run, calling him/her a “stiff” may not be taken as the compliment you intended it to be.
