The mobility craze has been sweeping gyms, and bookstores, for a while now. You must have seen those huge brightly colored elastic bands and pretty extreme and also pretty impressive positions people are able to contort themselves into.

More mobility or range of movement must be better right? If someone offered you more speed or strength you would bite their arm off, I know I would!

We may have two issues here. The first is that more range may not simply = better performance in a workout or your sport or even if it is guaranteed to transfer to these other movements.

The second point to be addressed here is can the pursuit of that range actually be detrimental to what I am about to do next in my training?

 

More equals better? Well yes and no!

 

Mobility work is often performed at the beginning of a training session. It makes sense that if I want some more range in my training then I should start off my session by getting that range!

This maybe where the problems start, although you maybe increasing range as a short or even long-term effect, is this range actually having a beneficial effect on the training about to be undertaken?

Well I suppose that depends on if your client has come to you to get better range in their hips or get stronger, faster and fitter! So if they have come for better mobility then of course more equals better.

Mobility has almost become a competition in itself. Will we soon see it as a stand-alone sport?

Holding an extreme range for an extending period of time certainly will have an effect on the passive tissue with a higher stretch duration and intensity recommended *Click Here*

At the same time however this may have a very different and detrimental effect on your ability to produce force and power. *Click Here*

The study suggests that stretches for longer than 60 seconds will have the most detrimental effect on subsequent activities. The authors suggest that this duration is not normally performed anyway in therapy and fitness and generally this would be true apart from the mobility craze!

This was also the case in this study *Click Here* that compared 30 seconds and 60 seconds of the holding of the stretch of the quadriceps. The extra 30 seconds almost doubled the power decrease from 5.5% to 11.6%!

Hmmm. So here we have a problem. To get the mobility changes you may have to hold the position for longer and this certainly seems to be advocated by the mobility crew, but and a big but is that this is much more likely to have an effect on the strength, power or agility that you might need in your training or sport.

So therefore we may have to ask what is the aim overall aim of the training in the first place? To become more mobile and increase joint ROM or to perform better in the training or sport?

A reduced ability to produce force will have an effect on Olympic lifting or Crossfit for example as both require explosive force production ability to perform the movements.

*Click Here* *Click Here* Here is an example of more not being better when it comes to mobility. We see in both studies that actually the more flexible the runners then also the less economical they were.

 

Transferability

 

An extreme static position held for a significant amount of time will improve your joint range of motion, there is little doubt static stretching & mobility work improves your joint range. *Click Here*

The problem is we don’t see static ranges of motion simply correlate with our active ranges during movement. Just because you have better mobility does not mean you will use it outside of your specific mobility work and the specific context you used to achieve it. It is not a stick on to transfer over to all the movements you may want to use it for.

This study *Click Here* found that passive hip ROM did not automatically transfer to more functional activities. They found that even though there were large hip ROM increases this was not utilized during movement.

These researchers *Click Here* also found that passive ranges of hip extension measured using the modified Thomas test were not reflective of the dynamic ROM used in running.

Just because you have anatomical potential at a joint does not mean the Central nervous system (CNS) will automatically use it in active function related situations.

*Click Here* here they found that soccer players benefited from dynamic movement preparation compared to static stretching during a kicking motion. This was more than likely due to the integration into a relevant movement.

The CNS is more of a player in increases of mobility than it is given credit for in some circles. The passive bits seem to get much more attention when there contribution could be smaller than is usually indicated.

 

CNS and ‘how it feels’

 

*Click Here* Here the change in passive range of movement could not be attributed to changes in muscle or tendon structure as often suggested. Instead an increase in the ability to tolerate a greater stretch of the sensory endings was cited as a more likely explanation.

Are your muscles, capsules or ligaments actually gaining structural change in mobility or does it just feel better so therefore we go further into the existing range? Has the sensory end point changed?

This piece *Click Here* also explores the question of changes in sensation rather than mechanical changes in muscle length. Whether a muscle is actually too short at a structural level or simply does not want to change stiffness and become more compliant or extensible is hard to tell but seems more likely to be the latter.

The nervous system regulation of muscle length or wanting to “put the breaks on” is certainly not given enough attention by the fitness industry and may actually (hopefully!) change our view of flexibility in the future.

 

CNS ‘excitability’

 

Both of these papers *Click Here* *Click Here* address the changes in the CNS during static stretching. We see a decrease in spinal reflex and motor pool excitability in this case measured by looking at the H reflex. This makes sense as to increase range we need to decrease resistance from the neural aspects that govern it.

The question is do I have tight passive elements in the first place and how much do I want them to be stretched anyway?

Spinal reflexes will kick in the quicker we move to help regulate range and in many situations, such as counter movements during throwing or kicking, enhance force production.

We see power reductions after static stretching as our motor pool excitability and spinal reflexes are important parts of our movement regulation and force production mechanisms.

This decrease in excitability that gains mobility is probably the same mechanism that also reduces force production!

 

CNS & Force production

 

This study *Click Here* found that even static stretches of 30 seconds decreased force production and muscle activation. Interestingly this was also true of the un-stretched limb. This shows that not only did it have a local effect but also a central effect involving the CNS.

So it maybe entirely possible that performing static mobility work on your legs still may effect your chest workout.

*Click Here* A static stretch protocol of 45 seconds produced a 9.5% reduction in isometric MVC (maximal voluntary contraction) of the quadriceps for 120 minutes post stretch that would be a whole soccer match plus extra time too. We did not see a change in vertical jump performance that could mean other muscles were able to change their contribution. This may however have implications for fatigue of these muscles.

A static stretch could even impact on explosive performance for 24hrs *Click Here* while a dynamic stretch may produce positive benefits for 24hrs.

The peak torque reduced *Click Here* for the bicep femoris muscle after a static stretch protocol of 30 seconds but not for the dynamic stretch.

 

Want more mobility?

 

If you want more mobility then rather working specifically on what is available at a joint in terms of passive range we could simply use movement that demands more mobility in our training. If you want a deeper squat….well work on squatting deeper.

Eccentric training has been shown *Click Here* to be an effective method of increasing lower limb flexibility. In a squat the eccentric phase would be the part going down.

If you want more ability to ‘open up the hip’ then you could work on movements that do this rather than isolating out the passive components. The anatomy may not even be the limiting factor.

Another point is that there is no point in having good mobility/flexibility if you don’t then utilize it. Training that moves through different ranges and planes will make a more mobile system without the need for stretching or specific mobility work.

Movement is a lot more than just passive joint range. It involves motor control, stability AND mobility, strength and power. Your movement potential COULD be limited by the passive structural components but anyone of the biomotor qualities mentioned could impact on your joints ability to go through the available range during your workouts or sport even if your range is great.

 

Dynamic stretch

 

A four week dynamic stretching warm up *Click Here* actually increased longer-term or sustained power, strength, muscular endurance, anaerobic capacity and agility performance enhancements compared to a static stretching program.

Here *Click Here* we see an active approach to stretching increased peak power, velocity and force with a time to peak potentiation of 3-5 minutes.

In this study looking at static vs dynamic warm ups *Click Here* they found no difference in flexibility between the two but did see an increase in jump height for the participants who used the dynamic warm up.

Not all studies seem to find static stretching problematic although the body of evidence certainly does not support it! This study *Click Here*  found the static stretch of 30 secs simply had no effect on leg extension power but a dynamic stretch enhanced muscular performance. The question is does this short duration have an effect on mobility?

 

Other stuff

 

People also stretch and work on their mobility for a whole host of other reasons.

Posture is often one. Here they looked at hamstring flexibility and lumbar spine curvature. *Click Here* This is an old favorite of the fitness community that tight hamstrings effect lumbar posture and lower back pain. Here they found that although hamstring flexibility improved it had no effect on lumbar ROM or curvature.

The same was true of scapulae posture *Click Here*. Attempts to change the position of the scapulae through the traditional stretch and strengthening model must be approach with caution and follow up measurements taken for confirmation of permanent change.

Injury prevention is another often-touted benefit of stretching. In this review of the effect of stretching on sport injury *Click Here* they found no greater reduction of injuries with stretching and therefore more ROM. This appears to be supported throughout the available evidence.

Stretching has also been discussed in relation to reducing the effects of Delayed Onset of Muscle Soreness (DOMS) *Click Here*.  Again this has also not been supported by the available research.

 

Conclusion

 

Although working on your joint mobility will over time give you more passive ROM there are still a heap of questions here.

Certainly we have to appreciate that transfer is not guaranteed to other training situations and the probability of having detrimental effects on our subsequent training increases the longer we hold extreme joint positions for.

One positive of the mobility/stretching debate is delving deeper into the science of the CNS, especially if you are anatomy focused, and an appreciation of the effects on both the motor and sensory components of the nervous system.

Are you actually changing your anatomy or does it just feel better to use it?

Does mobility need to be a standalone endeavor or could we just use our training and an increase in varied movement to make sure we have mobile joints AND a CNS that is happy and feels good about using them?

Lots of questions but as always fun to explore!