Muscle Cramps: Causes and Remedies Based on Latest Science

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By Corrine Malcolm,
CTS Ultrarunning Coach

When it comes to cramping, especially exercise-associated muscle cramping (EAMC) almost everyone has a story. A story about that one time, in that one race, where that one muscle seized. Exercise-associated muscle cramps are defined as painful spasms, and involuntary contractions of skeletal muscles that occur during or immediately post exercise. So, for the purpose of this article, that would exclude cramps that occur outside of the context of exercise, or that are caused by underlying medical conditions such as nocturnal cramps, hypo/hyperthyroidism, and central or peripheral nervous system diseases such as Parkinson’s disease.

Cramping is by no means a new topic in the endurance community, and because EAMC can be debilitating in a race scenario cramping remains a hot topic. There have been decades of research dedicated to trying to figure out how we cramp, why we cramp, and how to stop cramps once they start. Despite our long affair with EAMC, we are not much closer to fully understand their etiology. If anything, our new understanding of EAMC is that they are complicated and likely stem from multiple compounding factors that make any one treatment or preventative technique unlikely to work for everyone, every time.

The Old Theories About Cramping

The advancement that has happened over the past 5 to 10 years however, is a clear move away from the original “dehydration & electrolyte imbalance theory” and an increased focus on the “altered neuromuscular control theory”. Starting in the early 2000s, study after study appeared that looked at hydration status and blood-electrolyte concentrations in endurance athletes, and over and over again there was no significant difference in the hydration status or blood-electrolyte concentrations of athletes who cramped and athletes who did not cramp on race day. Moreover, if you think about it, dehydration and electrolyte imbalances are a system-wide issue, which should cause system-wide muscle cramping. However, EAMC is most commonly localized two one or two major muscle groups and frequently occurs unilaterally. What that means is that EAMC primarily occur in asymmetry (one calf cramps). However, if muscles are cramping bilaterally (both calves) or become generalized/full body cramping, this can be tied more closely to extreme dehydration or hyponatremia, or a more serious medical condition.

What this means is that although we should not completely eliminate dehydration or electrolyte imbalances entirely from the EAMC guidebook, there is likely more going on. Most likely, hydration and fueling problems act as one of the many players that work together to lead to EAMC.

The New Theories About Cramping

The newest theory knocking at the door is the altered neuromuscular control theory. The premise of this new theory is that EAMC is most closely linked to the tenuous relationship between your nervous system and muscles contractions. This theory suggests that EAMC are a combination of several factors coalescing in a perfect (terrible) storm, overexciting your alpha motor neuron, ultimately resulting in a cramp. The variables that are seemingly most important to causing this heightened fatigued state are: inadequate conditioning (particularly for heat or altitude), muscle damage, previous injury to both the cramping muscle or in the compensating muscle group, and certain medications like albuterol, conjugated estrogen, and statins. These variables can easily build off each other, snowballing into that cramp-prone state we’ve all seen happen on race day. These factors also explain why EAMC seem to been seen more frequently at hot races where muscles fatigue more quickly at the same work load, and why athletes with a history of previous cramping are most likely to experience cramping again. This also explains why we almost always see EAMC in races and not during training because we are placing a heavier demand on our muscles than we normally do.

What Happens When A Muscle Cramps

So how exactly do cramps happen and how do we try and treat them?

As mentioned above, cramping is the result of your alpha motor neuron becoming overexcited. Your alpha motor neurons are the largest neurons in your spinal chord and they directly innervate your muscle fibers, the stretch sensor, of your skeletal muscle. Their job is to send the message to your muscle to, “Contract! Contract! Contract!” We only move, pedal, kick, or stride when our alpha motor neurons work in perfect harmony with our Golgi Tendon Organs (GTOs). GTOs are the other half of the contraction-relaxation pattern our muscles rely on.

When alph motor neurons and GTOs are both functioning properly, the GTOs act as the inhibitor to muscle spindle contractions. Basically, your alpha motor neurons and muscle spindles are the active “Contract! Contract! Contract!!!” command and action, while the GTOs are the inhibition to the contraction and allow the muscle to relax. As our muscles fatigue, there is an increased firing from the muscle spindles to keep “Contracting-contracting-contracting!!!” while, at the same time, there is a decreased response from the muscle GTOs to relax. When both of these things happen, we get an over excited alpha motor neuron that causes the contraction to win out time and time again, resulting in a contraction that won’t stop or, as we’ve all experienced, a cramp.

What Muscles Are Prone To Cramping

Muscles that are most likely to experience EAMC are muscles that are contracting in a shortened position. This is particularly true of muscles that cross two joints including your muscles that make up your hamstrings, quadriceps, calves, your biceps brachii, and the long head of your triceps. EAMC are not limited to biarticulated muscles but they are the most common locations of cramping in runners, swimmers, and cyclists. Part of the reason for this is that when muscles have to contract in a shortened position, or through a small arc of movement, your GTOs produce less inhibition to the contraction than normal, due to altered muscle tensions. This can be made worse if you have an injury or an imbalance that causes you to decrease your normal range of motion.

The beauty of this knowledge is that one of the ways to stop EAMC once they’ve started is to stop and give your muscles the opportunity to lengthen. You can do this by stopping and passively stretching the muscle or by moving that muscle through its full range of motion. What you accomplish by doing this is creating a change in tension in the muscle, thereby increasing the GTOs’ inhibitory input to the alpha motor neuron and relaxing the muscle.

So why do people drink pickle juice?

Pickle juice appears to be more than folklore when it comes to stopping EAMC in their tracks. In a now famous 2010 study, researcher Kevin Miller and his colleagues brought pickle juice mainstream. For decades, athletic trainers and coaches had anecdotally been prescribing pickle juice, apple-cider vinegar, and mustard to treat EAMC, but there had been no concrete evidence as to why these various concoctions were stopping cramps. Playing into the electrolyte and dehydration theory, it was initially believed that the sodium in pickle juice was aiding in correcting an electrolyte balance in the cramping athletes. However, the result was happening so rapidly (30 seconds) it was deemed unlikely that the small amount of pickle juice ingested could possibly alter the athlete’s blood sodium concentrations in that short timeframe. What the scientific community began to conclude was that something in the pickle juice was abating the cramps via another mechanism. A new idea emerged that a neural reflex in the mouth, oropharynx, or esophagus could quickly disrupt the alpha motor neuron, stopping a cramp. This discovery has led to the development of several new anti-cramping products.

This new area of research (and the associated sports products) is based on stimulating transient receptor potential (TRP) channels. TRP channels are ion channels in the body that help mediate a variety of different sensations including pain, tastes, hot, cold, and pressure. Many TRP channels that help us differentiate temperatures are also activated by various molecules found in spices, such as capsaicin (chili peppers), menthol (mint), cinnamaldehye (cinnamon), shogaol (ginger), and allyl isothiocyanate (wasabi). Two channels of particular interest to researchers in this are the TRPA1 and TRPV1 channels that are found in our mouth, oropharynx, esophagus, and stomach. Given how fast the acetic acid in pickle-juice works to abate a cramp, it is very likely it stimulates TRP channels above the stomach, which makes this a particularly interesting way to address cramps once they start.

What this means is that strong sensory stimuli activated at these specific TRP channels, by a TRP agonist, or activators for each channel, like capsaicin, could potentially cause the alpha motor neurons to become less excited, which would in turn diminish or stave off a cramp (16). There are two possible scenarios being considered by researchers and companies cashing in on this new theory: 1) pre-ingestion of a TRP agonist might increase the threshold one has to reach in order to cramp, thereby keeping the individual out of a cramp prone state longer, and 2) ingestion of a TRP agonist at onset of a cramp will “trip” our electrical wiring, causing our muscle spindles and GTOs to work in harmony once again by decreasing the excitability of our alpha motor neurons.

What You Can Do About Cramping Today

So what does this mean for us right now? What the literature is currently telling us is that, although there is not yet strong evidence to support the idea that ingesting a TRP agonist pre-activity will successfully stave off a cramp, there is fairly strong evidence that ingesting a TRP agonist at the onset of cramping is likely to help abate the cramp and temporarily prevent subsequent cramps from occurring. I would add that at this time more research needs to be conducted on the most researched TRP agonist, HotShot, and other products containing TRP agonists like mustard, apple-cider vinegar, menthol etc. We are just at the beginning stages of understanding the complexities of TRP channels, the electrical component of EAMC, and their physiological intricacies.

So what can you do right now?

  • Experiment! Anecdote is not science. The brain is incredibly powerful, and placebos can have very real effects on physiological symptoms and performance. It doesn’t mean that something will not work, but the reliability of such methodologies remains unproven.
  • Train yourself specifically for the event you are undertaking. It’s thought that when the demand you put on your muscles does not match up with the training you’ve done, you are more susceptible to cramping, as evidenced by most cramp occurring during a race or event. This applies to athletes who go into events without acclimating to heat or altitude, who go faster than they train, and who fail to prepare for the types of terrain they will be competing on. Nothing can protect you from being underprepared for an event, not even the powerful miscalculation of our own limitations.
  • Work on form, mobility, and range of motion. Muscles most affected by EMAC are those that are confined to a small arc of motion, in a shortened state, and used repetitively. For runners, avoid heavy braking and focus on manipulating your stride length (in training for race day) so that you can maintain adequate hip and knee flexion and extension. For cyclists, make sure you’re seat position is high enough to allow for greater range of motion.
  • Fuel adequately. Glycogen depletion and inadequate fueling can lead to premature muscle fatigue and increase your risk of cramping.
  • Learn to recognize your body’s pre-cramping state and respond accordingly. Slowing down or stopping to stretch cramp-prone muscles could save you from that DNF, or from crawling into the next aid station.
  • Be reflective. Evaluate the training or race-day scenarios that may have brought you to your knees. What factors may have combined to lead to the over-fatigued state? For me personally it’s been a journey of rejiggering my biomechanics and imbalances.

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Comments 26

  1. In the late 1990’s I started doing the California Double Century series, a group of 25 rides each year that are 200 miles, completed in one day. I noticed the rest stops made available by experienced cyclists had rolls of Tums available. I asked why and was told they worked well for leg cramps. I experimented with them and discovered that chewing 2 of them thoroughly (not swallowing) usually terminated an active leg cramp.
    Cyclists most frequently get cramps in the earlier months of the year when building distance from 1-2 hours to 10 or more, and after stopping cycling for the day, especially when inactive for 30 minutes or more like sitting or napping. I keep rolls of Tums at the 2-3 places around the home when I can be inactive. After chewing the Tums the cramp quickly goes away.
    Many riders who have read my Thinking Cyclist tips on Tums now carry them on longer rides and store them at home, no one has every told me that they do not work for them.

  2. Excellent article, Corrine. Thanks. Like many of my fellow age-group athletes, I have experienced debilitating cramping, always in races and yet never in preparation for those races. Nerves? Jitters? I don’t know. What I do know is that the pain is terrible, that it has invariably happened for me near the end of the bike leg of multi-sport events, and that I have always had to come to a complete stop and wait (and wait) for the cramp–usually in one of my calves–to subside, rubbing it as best I can as it begins to ease up. From there it’s been a 70% pedal to the T-zone followed by a limping R2 to the finish. Terribly frustrating, especially considering all the preparation, not to mention the time and expense to travel long distances to national and world events.

    Like many other respondents, I have been on a quest to find ways to overcome my mid-race cramping. Articles like yours are a huge help, as are the posts by fellow “crampers.” Like many of us, I’ve grabbed at many of the life preservers listed in the posts. In the past four or five years I’ve made a number of adjustments: training patterns; dietary; fluid intake; rest; stretching, shoe inserts, etc. I’ve also read everything I can about the newer hydration and anti-cramping products that have come on the market in these last years, and I know most of you have too!

    The good news for me is that I haven’t cramped in at least my last twenty multi-sport races. For what it’s worth, here’s what I’ve added–in addition to the “adjustments” listed above–to my pre-race regimen: 1) The day before: a packet of Gatorlytes in a big bottle of Gatorade or anything like it. I’ll sip it most of the afternoon; 2) Race morning: With my oatmeal/banana/coffee I’ll take three SportLegs. Once I’m dressed I’ll slather Hyland’s Leg Cramps lotion onto both calves as well as my hamstrings–just in case. 3) 20 minutes before the start: a vial of HotShot. The sharp taste takes some getting used to, especially holding some of it in your mouth and swishing it around, as per the recommendation. I also place a spare vial in the middle-back pocket of my race jersey–just in case. Three extra ounces to haul around the race course, but I take comfort knowing it’s there.

    Overkill? Here’s what I know: I haven’t cramped in a long, long time, and I want to keep it that way. This pattern has worked for me. We all have to find our own way.

  3. Thank you CTS, as always I very much enjoy these articles. there truly is so much information out there and everyone’s story is so very compelling. While I personally sell hydration products the very first thing I say to athletes, cyclists in particular when they we discuss cramping “when is the last time you had a proper bike fit?” No matter what the remedy may be, if your body position and training is not optimum I believe nutrition alone will not help. Proper Hydration pre, intro and post is key to any physical activity. There are just those times that no matter what we do cramping might set in and this is where these new studies and old remedies come in very handy, if they work I say what ever makes the experience better, do it! 4oz of hydration every 15 minutes helps, if you are depleting more electrolytes than your body is able to produce this is when you will need to “supplement” using an electrolyte mix, not a “sport drink”.

  4. I got my first cramp at 13. Mine are severe to the point that I can no longer move until they subside. I’m 60 now and seem to get them even when fully hydrated and we’ll conditioned. I have recently found a miracle in pickle juice. I have a sip and within seconds they go away. I’ve gone decades with no relief and am excited to finally find something that keeps them at Bay.

  5. I’m 65, and had been seeing an increasing trend towards large leg-muscle cramping (particularly calves) on longer rides like Centuries and Gran Fondos, and nocturnal cramping too. More training helped, better nutrition and electrolyte drinks helped, but the biggest improvement for me was boosting my Vitamin D levels. Hah, perhaps too much sunscreen? Anyway, doing a daily loading dose of 10,000 IUs for a couple of months and then going to a maintenance dose of 5000 IUs has made a dramatic difference to me. Your mileage may vary.

    Here’s one of many articles that mentions (from a general, not athlete-centered viewpoint) a relationship between Vitamin D deficiency and muscle cramps:
    http://www.vitaminddeficiencysymptomsguide.com/vitamin-d-deficiency-and-muscle-cramps/

  6. yep, the cramping thing plagued me as a kid growing up. my cramps would be so bad that i limped around in pain for days. A person said i had a calcium deficiency. I experimented for some years with different supplements and discovered that if i took a good chelated multi-mineral with a 1:1 ratio of cal-mag I pretty much clear up my debilitating cramping to the point where it is now nonexistent as long as I keep up a regular regimen (3-4 doses a week). I am a avid mountain biker and enjoy endurance events so dealing with cramps is paramount to me.

  7. Pingback: Ultramarathon Daily News | Tuesday, May 22 | Ultrarunnerpodcast

  8. I am 74 and have been riding for 35 years (3K-6K/year). The vast majority of leg cramps occur when I wake up during the night and move quickly out of bed or stretch my muscles before getting out of bed. I still feel that adequate fluids are the key and the more I ride the more likely I will cramp in the above described situations.

  9. I can testify to the conjugated estrogen causing major problems with cramps. I never had issues with cramps before starting, would get severe charliehorses with even mild stretching or effort (really made training difficult) while taking it, then completely resolved when I stopped.

    My prescribing MD looked at me like I was nuts when I told him the HRT was giving me problems with cramping. He had never heard of the correlation (I hadn’t either until I experienced it and asked Dr. Google)

  10. Hotshot, soy sauce, and pickle juice works. Period. I don’t care what any study says, I did my own study on myself as everyone is different. If it’s a placebo effect, fine, I’ll take it. Cramps are just debilitating painful. For me, it was always the sartorious muscle and quads. (Cyclist), both two joint muscles. This article makes perfect sense to me as I’m a PT and understand how muscle contraction works. What I’m not getting is how this stimulus works when taking it at the beginning of your event. TRP channels are very fast acting to my understanding. How does this stimulus “linger” and still be effective for hours before cramping even begins? Great article, thank you!

  11. Very informative article. But i had to laugh at the pickle juice discussion regardless of its validity. It reminds me of fad diets as the solution to obesity. We all have propensity to cramp, albeit at different trigger points. But the #1 solution that gets too small a mention, including in this article, is adequate training for the event we are doing.

    One personal example: i had the good fortune of being paced up a hill by a retired top 5 world pro mountain biker in an attempt to set an early season PR. I completed all of the pre-day and pre-race protocol that an elite athlete (which I am not) would do to be ready. I was on PR pace with no early race mistakes (e.g. going out too fast) due to the pacing guidance. 2/3 of the way up the hill I had calf massive cramps eliminating my chance at the PR. I asked the pro (who knew of my training) whether it was inadequate hydration or electrolytes. He laughed . . . “just undertraining”.

    “With my tail between my legs” I learned my lesson and starting using Training Peaks to get my fitness (CTL) and power levels (PDC) to the demands of the event with proper rest (TSB). The cramps have almost never reappeared.

    The lesson I learned: If I want a temporary solution – buy pickle juice (or whatever the latest craze becomes). If I want a permanent solution – get trained.

    1. Hi Bob,
      Thanks for your thoughtful comment. If you read the take home points I strongly encourage and stress that being properly prepared is by far the best way to stop cramps before they start and avoid them altogether:
      “Train yourself specifically for the event you are undertaking. It’s thought that when the demand you put on your muscles does not match up with the training you’ve done, you are more susceptible to cramping, as evidenced by most cramp occurring during a race or event. This applies to athletes who go into events without acclimating to heat or altitude, who go faster than they train, and who fail to prepare for the types of terrain they will be competing on. Nothing can protect you from being underprepared for an event, not even the powerful miscalculation of our own limitations.”

      However, the “pickle juice” discussion and more specifically the talk about TRP channels and how they work is very much not a fad and has helped to steer science into understanding that the old electrolyte imbalance theory of cramping is not intrinsically accurate when it comes to EAMC. So yes, I agree wholeheartedly that the best way to avoid cramps is to be properly trained for the specific race demands (including environmental factors) that you might face… however, understanding how to stop cramps if they do start is both interesting and for many really helpful since the science has been slowly changing.

  12. Pickle juice works. So does Hot Shot, but I can down pickle juice MUCH more easily. But them prepackaged and carry 1 in your vest, as it can save your day.

  13. Great article. I think my cramping is due to Statins. How can I fix that? I’m trying to talk my doctor into lowering my dosage. As of now I am at 80mg. Also I cramp when I reach muscle fatigue or failure. Going to hard too long.

  14. Strange N=1…. started to take taurine which is aid full for my Crohns Disease. I never had cramps anymore. Other people around me without CD reported the same.

  15. All good info! Also, seems an earlier CTS article mentioned aging as a factor in increased risk of cramping. Definitely true for me, now 60. The strategies mentioned have all worked for me – “honestly” matching race effort to training level, slowing down in the heat, and pickle juice! Thanks for all you do to keep us motivated, well-trained and race ready!!

  16. Pickle juice and mustard packets (minit-stop!) have been life-savers for me. I did try the hot shot once which was similar to the cinnamon challenge for me and I thought I would die. It did take my mind off the cramps though. Since I am a major sweater, I do add salt to my bottles on a hot day and make sure I down at least a large bottle an hour. Backing down the heart rate when the pre-cramp twitches begin has got me to the finish. Thanks for the great articles.

    1. check into getting your sweat tested, not only extremely helpful to know how many of those salt tabs you should down per hour, but also makes for interesting cocktail hour conversation.

      1. Hi Guys,
        We’ll get a full reference section posted shortly but here are some of the articles for you to read:

        Pickle Juice Study referenced in the article:
        Miller, K. C., Mack, G. W., Knight, K. L., Hopkins, J. T., Draper, D. O., Fields, P. J., & Hunter, I. (2010). Reflex Inhibition of Electrically Induced Muscle Cramps in Hypohydrated Humans. Medicine & Science in Sports & Exercise,42(5), 953-961. doi:10.1249/mss.0b013e3181c0647e

        Articles looking at product like Hotshot (although more unbiased research needs to be done):
        Short G, Hegarty B, MacKinnon R, Bean B, Westphal C, Cermak J (2015) Orally-administered TRPV1 and TRPA1 activators inhibit electrically-induced muscle cramps in normal healthy volunteers (S17.003). Neurology 84(14 Suppl).
        Behringer, M., Nowak, S., Leyendecker, J., & Mester, J. (2017). Effects of TRPV1 and TRPA1 activators on the cramp threshold frequency: a randomized, double-blind placebo-controlled trial. European Journal of Applied Physiology,117(8), 1641-1647. doi:10.1007/s00421-017-3653-6

        Finally an article looking at ultra runners specifically:
        Schwellnus MP, Nicol J, Laubscher R, Noakes TD. Serum electrolyte concentrations and hydration status are not associated with exercise associated muscle cramping (EAMC) in distance runners. Br J Sports Med. 2004; 38:488–492. PubMed doi:10.1136/bjsm.2003.007021

        The total reference list will have approximately 20 references.

  17. I’m 62 and still train like I was 30 and doing short distance triathlons. Since having two vertebrae fused to mitigate spina bifida occulta at 52 years old I am experiencing cramping after as little as half an hour of swimming. I am learning that what you did to your legs in the previous days to a swim will portend cramping. This is why it’s swim, bike, run. So too true for me is facet joint pathology that puts pressure on the nerves as they exit the spine. The age factor plays here too with arthritis kicking in for some. The old saying, “Physician, know thyself.”, applies to all of us.

    Thanks for the wonderfully articulated article! I tried Hot Shot before it was known as such and have a gallon of pickle juice under the sink.

  18. Most interesting. Many years ago I suffered from cramps regularly in cycle races. I then for different reasons took action to sort out my digestion system and ensure I had the correct / the best I could get micro organisms in my gut. The cramps from then almost completely disappeared.

  19. Excellent and thorough Chris! I got my sweat tested for electrolyte content and found that of the 250 athletes are so they had tested I was the highest w almost 2000 mg/hr lost. And rate of loss important too. Replacing 75% of those electrolytes an hour has helped me immensely, as does the TRP approach pre race with hot shot. Cramping was my biggest concern going in to the Breck epic and with this approach it was a total, total non-factor. But I was real tight with those electrolytes, calorie and water replacement. Like you said everyone is individual and experimenting is the best approach. As a medical person myself it still baffles me we can’t figure this out…

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