It’s a Stretch!

In our Biomechanics of Human Motion class, we’ve been looking at the topic of flexibility and range of motion – i.e., stretching.   I thought I knew a thing or two about this topic.  In reality, I knew a smidgeon.  Humbling!

Let’s walk through what we’ve covered in class.  As with most biomechanics, it’s important to start with the micro and build up from there.  In describing this, I’ll draw heavily on Joseph Hamill’s book Biomechanical Basis of Human Movement, 4th edition, p. 116-118.   This text is an amazing compendium of everything biomechanical, from anatomy and physiology to muscular force production.  Not an ideal nighttime read, but after a good night’s sleep and with a strong cup of coffee, this book has plenty worth exploring.

Hamill defines flexibility as “the terminal range of motion of a segment,” such as a hip or leg.  This is comprised of both active and passive elements.  For example, during the running stride, our hamstrings actively engage to pull our leg behind us and then passively engage as we reach the top of the range to terminate the forward “swing phase” in preparation for the quads to pull the leg down.   If we are inflexible, then this total range of motion is limited and we begin the “stance phase” (when our foot meets the ground and pushes us forward) before enjoying the benefits of a full stride length.  This results in less “float” (the time we’re airbound), which gives muscles a chance to momentarily relax and regenerate force.

There are two main components that contribute to flexibility:

  1. Joint structure
  2. Soft tissues (muscle and fat) and connective tissue, primarily tendons and ligaments 

Healthy joint structure does not always follow the textbooks.  We’re not all built exactly the same.  Some of us have larger bony projections than others, with the fit of the femur onto the tibia, for example, varying among people.  While important, joint structure is not the major determinant of flexibility.  Rather it’s the muscle and connective tissue length and elasticity, which can be enhanced with stretching.   It follows that if we increase our range of motion, this will help our running. 

I’ve been testing this out the past four months incorporating a pretty rigorous stretching routine 5-6 days a week encompassing all the major lower extremity muscles including the soleus, gastroc, hamstrings, quads and various hip flexors.  This isn’t new – I’ve been stretching for years.  But what has changed is that instead of holding stretches for ~5 seconds, I’m holding them for a full 30 and doing multiple sets.   These are easy stretches – pain, no gain!  The second and third sets show noticeable increased range.  After three sets, change is minimal, so I call it quits.   Suffice it to say, this stretching routine is a big commitment.  It takes 20-25 minutes, so about two hours a week in total.  When time is tight, it cuts into my running mileage.

Has this helped my running?  I think so.  For example, last month I ran the New Hampshire 10 Miler at a pace four seconds per mile faster than at that race three years ago.  The age grade tables say to expect a 14 second per mile decline over those three years, so for my age that’s an 18 second per mile delta and for 10 miles a three-minute age-graded improvement.  I’ll take it!  But perhaps more important, it feels better running.  I start training runs less stiff and after a mile or two more easily up the tempo.  When racing, assuming a good warmup I generally feel ready to run with a bit more “bounce” in my step.  That’s not to suggest the racing is easy!  We test our limits, whatever the time and place achieved. 

Regrettably, stretching is one of the last things runners take time to do.  The aim of this post is to get you excited about regular stretching!   There are two types of stretching — dynamic and static.  Each have their place with easy dynamic (moving) stretching good before our runs and static (holding) afterwards.  The order is important.  The research shows dynamic stretching before runs positively impacts running – getting us ready to run – whereas static stretching negatively impacts us.  The reasons for this are somewhat technical, but the short of it is our muscles and joints loosen up during exercise and thus are more receptive to stretching.  This allows for a more relaxed and deep stretch, which if done consistently can permanently increase our range of motion (assuming we consistently follow the program.)   

As with all things running, training is a complete package, balancing aerobic and anerobic running with strength and flexibility work.  It’s hard to maximize our potential at any age without a serious commitment to all four aspects.  I’ll look for you on the stretching mats at the gym!

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