I’m just about fully recovered by a sudden case of shin splints and calf cramps in both legs this past Monday. I did no running, just walked for a little over 4 miles between our house and the shopping mall.
I thought I was doing pretty well until I got about a half mile from home. I had to cross a relatively busy street that doesn’t have a traffic light control, just a sign that suggests drivers slow down and stop for pedestrians in the crosswalk. Many drivers breeze through at around 30 mph and so I generally wait until there’s no traffic or when cars slow down enough that I can’t see the driver’s maniacal grin.
As a few cars waited, I began to cross the street and about halfway over, I started to trot and immediately both my calves cramped up. It was painful and I just managed to limp over to the sidewalk. As I leaned over and tried to ease the cramps by grabbing my toes and bending them toward my shins, I wondered why that happened.
Part of the reason was this was the first long walk of the spring after a winter of being relatively sedentary, other than some routine exercises including stationary bicycle, step box, and stretching routines.
I’m used to shin splints, which I noticed before the leg cramps. But I’ve never had both calves cramp like that. I’d gotten enough fluids, I wasn’t dehydrated, and I wasn’t low on electrolytes. Then, I got curious about the interplay of all those and found out there’s a fair amount of controversy about the causes of what I found out was called exercise-associated muscle cramps (EAMC)
Shin splints are a minor annoyance and could be due to me just being an old guy overdoing it and wearing not the greatest shoes on a concrete trail. Resting a while is the main way to get past it. But because of the double whammy of bilateral shin splints and calf cramps, I hunted on the internet for studies of the causes of EAMC, specifically calf cramps.
I’m sure most readers are familiar with web resources like the Cleveland clinic, which provide general guidance. They usually recommend avoiding dehydration and staying up to speed on electrolytes. Rest is the main suggestion. Meditating over an oleomargarine figurine of Elvis Presley is not recommended but has not been sufficiently studied.
Anyway, I found an interesting web site which challenges the usual guidance about the causes of EAMC. One of the authors of an article (“What Are the True Causes of Cramps While Running?” by Phattarapon Atimetin, MD; published May 15, 2019 on the website samitivejhospitals.com website) disputing the cause of EAMC being dehydration or mineral deficits pointed out that these are less likely than something called “altered neuromuscular control,” which appears to be advanced by a scientist named M.P. Schwellnus. However, the author didn’t cite any references, so I had to hunt them down. I think I found the right articles.
I found one the author didn’t mention, which was a comprehensive review (note the publication date, a few months after Dr. Atimen’s article):
Maughan RJ, Shirreffs SM. Muscle Cramping During Exercise: Causes, Solutions, and Questions Remaining. Sports Med. 2019 Dec;49(Suppl 2):115-124. doi: 10.1007/s40279-019-01162-1. PMID: 31696455; PMCID: PMC6901412.
The authors’ bottom line is:
Exercise-associated muscle cramp is a relatively common occurrence in a range of sport and exercise activities. Onset is generally unpredictable, and the intensity and duration of muscle spasms are highly variable. Spontaneous muscle cramping in occupational settings involving hard physical effort suggests that high ambient temperature and large sweat losses accompanied by the ingestion of large volumes of plain water may be risk factors, and there is some evidence that the risk is reduced by the addition of salt to ingested fluids. Laboratory models of cramp involve either voluntary or electrically-evoked activation of muscle held in a shortened position. These studies have produced mixed results regarding the effects of disturbances of water and salt balance on the risk of cramping; however, they do suggest that, at least in this model, sensory organs in the muscle invoke abnormal reflex activity that results in sustained motor drive to the afflicted muscles. There may be different mechanisms at work in different situations, and there is no conclusive support for any of the proposed mechanisms. Preventive and treatment strategies are not uniformly effective.
They mention M.P. Schewllnus, but they don’t endorse the altered neuromuscular control theory or any other as being explanatory in every case of EAMC. The review was supported by the Gatorade Sports Science Institute (GSSI), which makes me wonder about it a little.
I’m not certain but I think the references for the studies Dr. Atimen mentioned are below:
Schwellnus MP. Cause of exercise associated muscle cramps (EAMC)–altered neuromuscular control, dehydration or electrolyte depletion? Br J Sports Med. 2009 Jun;43(6):401-8. doi: 10.1136/bjsm.2008.050401. Epub 2008 Nov 3. PMID: 18981039.
Braulick, K. W., Miller, K. C., Albrecht, J. M., Tucker, J. M., & Deal, J. E. (2013). Significant and serious dehydration does not affect skeletal muscle cramp threshold frequency. British Journal of Sports Medicine, 47(11), 710-714.
Hoffman MD, Stuempfle KJ. Muscle Cramping During a 161-km Ultramarathon: Comparison of Characteristics of Those With and Without Cramping. Sports Med Open. 2015;1(1):24. doi: 10.1186/s40798-015-0019-7. Epub 2015 May 21. PMID: 26284165; PMCID: PMC4532703.
The reference below is more recent and the authors’ bottom line is below:
Kevin C. Miller, Brendon P. McDermott, Susan W. Yeargin, Aidan Fiol, Martin P. Schwellnus; An Evidence-Based Review of the Pathophysiology, Treatment, and Prevention of Exercise-Associated Muscle Cramps. J Athl Train 1 January 2022; 57 (1): 5–15. doi: https://doi.org/10.4085/1062-6050-0696.20
Advances in our understanding of EAMC pathogenesis have emerged in the last 100 years and suggested that alterations in neuromuscular excitability and, to a much lesser extent, dehydration and electrolyte losses are the predominant factors in their pathogenesis. Strong evidence supports EAMC treatments that include exercise cessation (rest) and gentle stretching until abatement, followed by techniques to address the underlying precipitating factors. However, little patient-oriented evidence exists regarding the best methods for EAMC prevention. Therefore, rather than providing generalized advice, we recommend clinicians take a multifaceted and targeted approach that incorporates an individual’s unique EAMC risk factors when trying to prevent EAMCs.
The review was not supported by Gatorade. It turns out the best management is rest and gentle stretching. If that doesn’t work, the advice is to seek advanced medical care. There is no evidence that meditating over an oleomargarine figurine of Elvis Presley is effective in any way—although, again, it has not been studied that I know of.
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