Friday, May 7, 2010

Muscle Cramps in Calves when Running in Vibram FiveFingers: what is it, what causes it and what can be done about it?

ResearchBlogging.orgRunners Cramp - Calves cramping - it's AWFUL. In talking with folks who run in VFF's it seems that one usual side effect initially at least is that, when picking up the pace in VFF's (perhaps especially up hill),  calves may start to cramp up. Guaranteed, if we keep going with this run, once that cramp starts, the calf or calves will turn to unyielding, painful rock.  What can be surprising is how quickly into a run this seize up can happen. What the heck is going on, and what might help stop it from happening.

There could be lots going on, so i'm not trying to be comprehensive and exhaustive  - not sure that's possible. The goal of this post is to look at pain generally, muscle cramps in particular and what's hypothesised about causes, introduce a newer model not seen in web discussions of cramp, and propose a refinement for that model. Finally, some practical suggestions of getting out of that cramp while heading to barefoot running freedom.

Pain is a signal for Change
Explain PainBased on work in pain, and as summarized in work by David Butler like the plain language Explain Pain, pain is a signal for change; pain does not necessarily, however, equal injury, and the site of pain is not always the source of pain; treating the site of pain therefore can be a losing proposition.

I've used the analogy of a car oil gauge regularly reading low. One solution is to top up the oil in the engine so that the gauge reads the right level. That level will only last short term and needs to be repeated regularly - and in the interim, what related problems might be developing from such regular loses?

Another solution is to do a diagnostic to find out what else might be going on - like a leak in the engine block where actually a bolt may simply need to be tightened (or an entire gasket in the block replaced - can you tell i'm having flashbacks of stripping the head of an engine in the middle of the bush on an old carola. never mind; i digress).  The point is, getting away from site = source often leads to better results.

 In the car analogy, finding a more fundamental issue, performing a wee tweak and testing if that tweak will work means that the oil level stays where it's supposed to be for as long as it's supposed to be there. Both approaches are a kind of solution; the benefits on the system and the wallet are better in the latter case.

What's a Cramp in the Calves Anyway?
So taking the above pain thesis into account, what does this mean for the calves rock effect?

What's a Cramp? A cramp is an involuntary and intense contraction of a muscle. What causes a cramp is a subject of much discussion, and poorly understood. A quick check on the web doesn't get at too much about why this contraction occurs.

WHy a cramp? The usual checks: electrolytes, hydration, low carbs, tight muscles to begin with are offered up not as reasons, but of things somehow thought to be related to cramping. Here's an examplary summary of that kind. In this model, the thesis seems to go, the muscles don't have the chemical materials needed to fire in that working limb properly so they effectively rigor mortis up. This rationale for cramp has been more or less tossed out as demonstrated here in 04, and as summarised in this recent BMJ review article. First, on dehydration:
A careful review of the literature did not identify a single published scientific study showing that athletes with acute EAMC are more dehydrated that control athletes (athletes of the same gender, competing in the same race with similar race finishing times). In contrast, there is evidence from four prospective cohort studies showing that dehydration is not associated with EAMC.
 And on electrolytes (and dehydration):
In summary, dehydration and electrolyte depletion are often considered together (and recently together with muscle fatigue) as the ‘‘triad’’ causing EAMC. The key components of this hypothesis (fig 1) are that electrolyte (mainly sodium) depletion through excessive sweat sodium loss together with dehydration causes EAMC. However, results from prospective cohort studies consistently show that athletes suffering from acute EAMC are not dehydrated, neither do they have disturbances in serum osmolality or serum electrolyte (notably sodium) concentrations. Furthermore, sweat sodium concentrations measured during exercise in 23 reported cases with a past history of EAMC are not higher than those reported in many other studies. Both electrolyte depletion and dehydration are systemic abnormalities, and therefore would result in systemic symptoms, as has been observed in other clinical conditions. However, in EAMC, the symptoms classically are local and are confined to the working muscle groups. Thus, the available evidence to date does not support the hypotheses that electrolyte depletion or dehydration cause EAMC — therefore an alternate hypothesis for the aetiology of EAMC has to be considered.
And here's another typical "it's because you didn't stretch right" response - but you'll note the article doesn't raelly say *why* stretching prior to running does or does not do anything for cramp reduction. Indeed, when it comes to running and stretching, the current scene seems to suggest that a stretching program - not necessarily something done prior to running, but just putting this into one's routine  - helps running mechanics. That's different. And has nothing to do with a pre-run routine to reduce cramps; as we'll see, stretching is used to respond to a cramp; not prep for one.

Here's another view of cramps by Luke Hoffman that could be written for VFF runners:

According to current theory in the sports science literature (as of 1997), skeletal muscle cramps during exercise probably happen when muscles that are shortened (for example, a calf muscle when your toe is pointed) are repeatedly stimulated. This can happen if your foot is extended, toe pointed, and you keep extending it further. You can actively do this by, for example, running on your toes or doing lots of toe-raises without going down to extend the muscle. What appears to happen is that the muscle gets fatigued, and it doesn't relax well. There is a reflex arc -- made up of the muscle, the nerves carrying signals to the central nervous system (CNS) and the nerves carrying signals from the CNS back to the muscle -- that keeps carrying contraction signals from and to the muscle. This appears to lead to a sustained contraction in the muscle, also known as a cramp.
Stretching (in this case, grabbing your toe and stretching the calf) is about the only thing that breaks this reflex arc signal and stops the cramp when it comes to exercise-induced cases. But the muscle is still fatigued, and the cramp process is easy to re-trigger until the muscle rests for a while. The fatigue-cramp process seems to happen most often in muscles that cross two joints, such as the calf muscle (which crosses the knee and ankle), since the muscle is easy to shorten and continue contracting.

The above describes what might be called "voluntary contraction" - not quite the same as involuntary. If we take the above council about voluntary cramps to bear, however, what should be the case is once a cramp starts, we should stretch it out, and wait for the fatigue to pass from that contraction, and recover, and really stop doing what we were doing - running on the forefoot. Consequently, Pose  & VFF runners who run on the forefoot should be cramping all the time. And if we believe work in barefoot running, this is rather how we're designed to run. So, hmm, maybe not.

None of these explanations therefore is complete it seems, to explain cramping we see in the calves that comes on unexpectedly, as lots of well fed, well hydrtated, well electolyted people who stretch still get cramps, and these weird cramps in VFF's in particular.

So why does this cramp only happen *some* of the time - especially if all the typical niceities of cramp avoidance are observed?  For me, for instance, it happened first when i started practicing actually bringing the heel of the foot down more (extending the calf) when running, rather than staying up on the forefoot. So, maybe it's not (entirely) about the calves?
Altered Neuromuscular Control. In the research one of the explanations around cramp is: maybe the muscle is just not strong enough to do what is being asked of it, for the duration it's being asked to operate at this level - hence fatiguing - and it's that fatigue that is setting up EAMC: exercise-associated muscle cramping. This hypothesis, also known as "altered neuromuscular control" was first proposed in 1996, so that's how new this stuff is. A key part of this model is that the neuromuscular control issue is located in the SPINE, not at the site of the issue - the site is paying for what's going on at the source.
There is a growing body of evidence to suggest that the mechanism for muscle cramping has a neuromuscular basis. Firstly, as has been discussed, voluntary muscle contraction or stimulation of the motor nerve can reliably cause muscle cramping. Secondly, there is evidence from experimental work in human subjects that stimulation of the 1a afferents through electrical stimulation or using the tendon tap (activating the 1a afferents) can induce cramping. Thirdly, it has repeatedly been shown that the most effective treatment for cramping induced in this manner is muscle stretching.
[WHY stretching?] An increase in tension in the Golgi tendon organ during stretching, which will result in increased afferent reflex inhibitory input to the a-motor neuron, is a plausible mechanism to explain why stretching is an effective treatment of cramping. [see Bertolasi and Co., '93]
There are other possible mechanisms that could alter neuromuscular control at the spinal cord level, and therefore may contribute to the development of EAMC. The first of these is the possibility that muscle injury or muscle damage, resulting from fatiguing exercise, could cause a reflex ‘‘spasm’’, and thereby result in a sustained involuntary contraction. The second possibility is that increased or decreased signals from other peripheral receptors (such as chemically sensitive intramuscular afferents, pressure receptors or pain receptors) could elicit a response from the central nervous system that can alter neuromuscular control of the muscles. These other mechanisms have not been investigated in athletes with EAMC, but would be important to explore in the future.

The Emotional Brain: The Mysterious Underpinnings of Emotional LifeSo in the Pain as Signal to Change perspective, cramps are painful; they are a signal to change. The altered neuromuscular control model suggests, stretch it out and recover. Related work suggests, improve strength/stamina to reduce fatigue and reduce this muscle cramp response. Both have in common that fatigue is causing neural level loss of appropriate control.

Wildly Hypothesising? What's going on when this particular response occurs well before one would think a muscle used to running for miles and miles starts to go all crampy?

In work pionered by LeDoux in the nineties, he showed that the brain processes emotional responses like fear/threat without the conscious brain being involved. It happens fast, at a low level, without cognitive involvement and has immediate chemical consequences in the system (nice review of this and related work here by Ohman, 2005). In other words, perhaps there's some other *thing* happening in the sensory-motor exerperience that is saying "not good" and the result is this fatigue-like chemical messaging system that sets off early light cramp signals - that if ignored will just get louder until one is forced to change patterns. 

In Z-Health, Eric Cobb translates this fear response into the nervous system's job to perceive threat or no threat: if there's a perception of threat, the system starts to shut down (example in arthrokinetic reflex).  What might be the threat ocuring in VFF ocaisional calve cramping? The system may be literally putting on the breaks to what it perceives as a threatening to it's well being practice.

It's easy to see that if the nervous system perceives that the task - going at a particular speed in a particular way - is causing part of the system to be over-taxed, it's going to respond to that as a threat or non-optimal situation, and if it takes pain to get change, well, whatever it takes.

Personal Experience. Taking a Z-Health approach to this experience, i think i've learned to become more alert to any pain signal my bod sends up in an athletic effort. So in this case, if and when these cramps begin, they usually start with a very mild "uh oh" twinge of "about to turn to rock if you don't respond."

There are two simple things that z-health suggests for rehabbing a movement with the cue of "never move into pain:"
  • reduce the range of motion
  • reduce the load
In running, this reduction can mean reducing speed and reducing the size of the gait. These simple changes have often been sufficient and successful to head off the cramps, let me consider the kind of terrain or inclination/declanation where the event is happening, and look at ways to practice this kind of run outside of threat - eg, do repeats on this kind of terrain, slowly bringing speed/gait up to snuff. At any sign of cramp, i back off. Now perhaps this is all about simple fatigue/recovery models to get the nervous system firing right, but it's intriguing that this "fatigue" can come on so seemingly suddenly in some cases, and that a mid-run gait change can have such an effect

Guided by the Nose: run to pace inhalation. Another technique i've been using and coaching to help head off cramps and adapt to barefooting generally is to explore gaiting running speed with ability to stay breathing in through one's nose. If running at a clip where i have to mouth breath, i slow it down (i find if i hit that level, it's pretty hard to get it back to nose inhaling). This approach is just one way at least some of the time to practice running reps quality rather than overdriving the other parts of the system.

Deeper Tune Up: Starting from the Source
So we've seen one theory in the research is around muscular fatigue inducing EAMC; getting stronger in those areas where muscles cramped seemed to help. In one study. That's great. Another possibility - that can lead to faster fatigue - is if there's some kind of issue in one's movement that is causing perhaps other muscles to compensate for other weaknesses, and causing fatigue/pain/signaling in the calves faster that should happen for that group. So while a solution may be to do extra strength work, maybe a faster solution may actually be to look at one's movement as a whole.

In other words, the calves may be plenty strong IF everything else is firing up appropriately, but they may be being asked to super compenate for other stuff, that if those other movement issues were addressed, wouldn't cause the problem.

There's value therefore in (a) having a movement assessment and (b) practicing dynamic joint mobility and sensory-motor work to ensure great movement, and ability to maintain great, clean movement.

Summary: Avoiding Running Cramps in VFF's
Based on the latest research, EAMC cramps are about temporary loss of clear neuromuscular control. The best model so far to explain this effect is fatigue. A known way to work out a cramp is to lengthen the muscle. There may however be other approaches that just haven't been researched that also seem to work. The hypothesis here is that these approaches are dealing with neurological signaling, too, taking advantage of the sensory-motor system.

Some pragmatic responses therefore if cramp occurs are:

During a Run: Assuming one is not dehydrated, de-electrolyted, or have squirrels biting their calves while running,
  • As soon as a cramp (pain) starts, change something - gait, speed, whatever; if that doesn't work, stop what you're doing.
BEFORE the run :
Why? Such range of motion, proprioceptive/vestibular/visual work enhances the sensory-motor signaling to the brain. The clearer the nervous system information, the more sources of information, the greater the options the body has to reduce threat.

And before That
Consider a movement assessment to check for what Gray Cook calls "weak links" so as not to build strength on top of dysfunction.

Let me know what works for you.

Schwellnus, M. (2008). Cause of Exercise Associated Muscle Cramps (EAMC) -- altered neuromuscular control, dehydration or electrolyte depletion? British Journal of Sports Medicine, 43 (6), 401-408 DOI: 10.1136/bjsm.2008.050401

OHMAN, A. (2005). The role of the amygdala in human fear: Automatic detection of threat Psychoneuroendocrinology, 30 (10), 953-958 DOI: 10.1016/j.psyneuen.2005.03.019

Bertolasi L, De Grandis D, Bongiovanni LG, Zanette GP, & Gasperini M (1993). The influence of muscular lengthening on cramps. Annals of neurology, 33 (2), 176-80 PMID: 8434879

Wagner, T. (2009). Strengthening and Neuromuscular Reeducation of the Gluteus Maximus in a Triathlete With Exercise-Associated Cramping of the Hamstrings Journal of Orthopaedic and Sports Physical Therapy DOI: 10.2519/jospt.2010.3110

Caplan N, Rogers R, Parr MK, & Hayes PR (2009). The effect of proprioceptive neuromuscular facilitation and static stretch training on running mechanics. Journal of strength and conditioning research / National Strength & Conditioning Association, 23 (4), 1175-80 PMID: 19528850

Schwellnus, M. (2004). Serum electrolyte concentrations and hydration status are not associated with exercise associated muscle cramping (EAMC) in distance runners British Journal of Sports Medicine, 38 (4), 488-492 DOI: 10.1136/bjsm.2003.007021
Schwellnus MP (2007). Muscle cramping in the marathon : aetiology and risk factors. Sports medicine (Auckland, N.Z.), 37 (4-5), 364-7 PMID: 17465609

Schwellnus, M. (2008). Cause of Exercise Associated Muscle Cramps (EAMC) -- altered neuromuscular control, dehydration or electrolyte depletion? British Journal of Sports Medicine, 43 (6), 401-408 DOI: 10.1136/bjsm.2008.050401

Related Sources


Unknown said...

Did the research quoted identify which "calf muscles" were cramping. I would suggest that perhaps the smaller muscles of the calf maybe more likely to cramp in VFF's because of the shoe design. That the design allows for these muscles to be more individually loaded (possibly?). Have users of VFF's found that cramping decreases over time? Curious.

Unknown said...

Could be due to a magnesium deficiency also.

dr. m.c. said...

DW, Kaye, thanks for dropping by.

To the best of my knowledge:

DW, the studies are about EAMC in general or about hamstrings in particular. While it's interesting to think about if there's anything special about vff's my sense would be only that we're getting used to (a) a different, normal gait pattern and that takes a lot of neural re- patterning, and (b)that's setting up some new possible perceived threats in the system. None of the research on this has yet been about barefoot runners.

yes lack of magnesium has been associated with things like charlie horses - involuntary cramping at night or when not moving.

That kind of systemic deficiency is very different from what we're disussing here, which is specifically exercise associated muscle cramps.

In the literature looking at folks of the same profile against folks who cramp, there's no significant differences between their blood serum, so in EAMCS that's been ruled out as a factor


Unknown said...

I noticed that I specifically get calf-cramps while surfing. I would abstain from alcohol, drink lots of water, eat bananas right before getting in the water. And still --- there's a 50/50 chance my calves will being intensely cramped. I thought it had something to do with "change" as well. Having been a runner for 5 years to switch to laying flat on one's belly, paddling with shoulders/chest/arms, while legs are relaxed and knees bent so feet out of the water. Then -- a quick burst of leg-energy to try to stand on the board === instant pain and insanely tense calf muscles.

dr. m.c. said...

thanks for posting.

Sorry about your surfing pain.

It's not normal. If doing normal surfing actions like you've described happen regularly, i'd check in with a coach. That cramp is a response to what you're doing - and your body doesn't like it.

Please let me reiterate that the research has shown that the whole electrolyte thing for exercise associated cramping is not supported, so it's not really likely that the issue you describe is dietary.

If you regularly experience pain after paddling out and jumping onto your board, there's a problem somewhere in something you're doing.

IF you're in san diego or there abouts there's a great movement coach/surfer to connect with; if you have a web cam, see him via skype. email me if you'd like information. Really, there's no need for any pain in the movement you describe if things are working right.
thanks for writing.


Sportfit Proformance said...

I've found that most people aren't equipped to handle running in the vibrams until we get the foot stable. Stability in the foot in pronation (90 deg dorsiflex talocrural joint, eversion subtalar joint, oblique axis pronation of the midtarsal joint, longitudinal axis supination of the midtarsal joint), and check to see if it's symmetrical to the other foot. If any of these axes are limited then that will put a strain on another axis causing a muscle or a number of muscles to be forced into a shorter position then it should be in. The same would go for supination of the foot (plantarflexion of the talocrural joint, inversion of the subtalar joint, oblique axis supination of the midtarsal joint, and longitudinal axis pronation of the midtarsal joint). I find that flexor hallucis longus and flexor digitorum longus are usually not working well which are huge ankle stabilizers (associated with plantarflexion), as well as the extensor hallucis longus and extensor digitorum brevis (asociated with dorsiflexion). Get the foot stable before you start running in those vibrams

dr. m.c. said...

Sportfit performance, thanks for dropping by.

"i've found that most people aren't equipped to handle running in vffs"

probably not what you meant - since we're all designed (equipped) to run barefoot. -and i mean designed to run more so than even walk.

if you mean folks who wear shoes need to spend time getting used to working those muscles to move barefoot, for sure, need time to adapt without pain.

is there a period of adaptation from supportive shoes to let muscles that haven't had to work start to work and not bring on horrible DOMS? yes, sure, that too.

It seems in self-reporting from most folks running in vff's that following the simple guidance of the company to give oneself time to adjust to barefooting takes care of those muscular adjustments that lead to "stability" if that's the issue.

It's odd though to see SUCH lack of stability in *just* the foot. There's usually more of a pattern in a movement. snf bigger problems are often with lack of mobilisation in the foot and other joints,

That said, none of this has meant that bare feet are contra indicated, or that the best way to get better at barefooting isn't the activity itself.

Hence test/try/reassess. If you can do that with a movement coach, so much the better.

In the meantime, put the toes in the long grass, go gently, slowly and listen to our bodies about what tests as safe, what's a threat and reduce the threat to improve the response, no?


Sportfit Proformance said...

When I say equipment I mean axis of motion. If you don't have 90 deg of talocrural dorsiflexion (not talocrural and midtarsal dorsiflexion) or an oblique axis of pronation you WILL have a problem at some point in time (a restricted foot is an unstable foot). I have seen a majority of people with these issues, and of course they lead up the body and back down, it's all related and affected. Most people should not be running just because they can. I think the barefoot craze will bring about more foot issues in the long run. Don't get me wrong i'm a big fan (I own 2 pairs), but only if the foot is working properly. Hoping and waiting for an "adjustment" period is purely speculation and even if someone perceives feeling better, are they really structurally and mechanically getting better? Or are they slowly buring themselves or building something up that will topple over at some point. Cramping is just an indication of weakness and something is not doing its job. It's a red flag that needs to be addressed. It doesn't just go away. Thanks mc

dr. m.c. said...

I think i hear what you're saying, which is very gray cook'esque in not adding strength on top of disfunction, and it's why i suggest movement assessments all the time - to help optimize movement.

my bet is that most of the folks you see wear pretty standard footwear/running shoes, maybe don't have a regular movement practice, or ever had a movement assessment?

That said, from working with folks, i see too many immediate benefits from getting OUT of shoes and progressively into footwear that passes the twist test.

And please note, when i talk about getting into footwear that passes the twist test, i don't mean ONLY for running; i mean all the time.

Perhaps if the only time a person wore flats was running and the rest of the time they were in highly structured non-twist shoes, that could be problematic because the foot is unprepared.

But it would be difficult to imagine - and i just haven't seen it - that folks who move towards twisty shoes, that let their bodies move as designed more of the time would get worse rather than better, holistically. I just haven't seen this - the sensory-motor benefits are too huge.

I'll aslo note that, if you've hung around b2d at all, you'll see that pretty much all the time i talk about connecting going barefoot with practicing good joint mobility - for the whole body - and good sensory-motor practice.

As for cramps being an indication of weakness and something not doing it's job, gosh, i guess if you've read this article, you'll see that i'm partially agreeing with that, but also suggesting that there may be be something else involved too - that can be addressed - if a cramp comes on faster than fatigue allows.

Please note that all the EAMCs research on running has been done with people wearing what folks normally wear for runners, and that these are elite athletes. Agreed they can all still have mechanical issues, but i don't think i'd suggest that running for them is contra-indicated.

So yes by all means get movement checked out and work towards optimal performance.

But i don't think the issues you describe mean that (a) progressively moving towards more natural footwear is contra indicated - after all if we want to improve gait, it helps to have footwear that lets those muscles act to support a natural use of them in a natural gait, no?

nor (b) walking or running with a more natural non heal-striking gait is contra-indicated

nor (c) therefore running/jogging while working on movement is contra-indicated.

I look forward to more studies that show the mechanical benefits of barefoot running over time - but considering the AUTOMATIC mechanical improvements that occur from barefooting as demonstrated by lieberman's research, its' hard to see how this could be a bad first step as it were to more appropriate movement overall.


Jason said...

Great post, as always, mc. It's like you wrote it just for me. ;)

Strong case for a movement assessment indeed.

Thank you.

Dina said...

Thanks for this post. I'm not a runner, but have started playing ice hockey in the last year. Recently (about last 6 weeks or so), I've been suffering from really tight calves, and in the morning if I stretch when I wake up (you know, just the "morning stretch"), there's about a 90% chance that will trigger an extremely severe and painful calf cramp (in one or sometimes both legs).

If I'm understanding your post correctly, the fact that I'm getting those cramps in the morning after sleep (as opposed to during exercise), would be an indication that perhaps it is more diet-related, right? More magnesium?

I have been stretching, and drinking lots of fluids. My calves haven't gone into complete cramping during skating yet, but they have felt like they were about to on several occasions -- started to get very tight.


Sarah J said...

I've had this happen twice now while running. Once barefoot and then with VFFs. I'm going to try the nose breathing to see if that helps. I know the last time I was pushing myself a bit and had forgotten my breatheright strip so I KNOW I was mouth breathing. boo. Thanks for this!
I've been running bare and in VFFs all summer and it's only happened twice.


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