Exercise Associated Muscle Cramps (EAMC)

DaFlip · Nov 23, 2004

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Just wondering the thoughts of the list on EAMC. There are many anecdotal theories on serum electrolyte and rehydration. None full supported through studies, and it is difficult if not impossible to actively reproduce EAMC in athletes. The mechanism of cramping more recently has been theorised to be associated with a sustained alpha motor neurone activity with muscle fatigue. However there are many cases of athletes cramping without being in a fatigued state. Any thoughts as to factors which may cause sustained alpha activity in non-fatigued athletes?? :confused:

dgroberts · Jun 15, 2005

DaFlip said:

...it is difficult if not impossible to actively reproduce EAMC in athletes. ....
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I can reproduce EAMC.........but only in me, and it's not pleasant :)

I train as a thai boxer and when training to fight, which is very intense, can bring on EAMC's if I don't take on water at the right time.
Basically a hard session involves running 5 miles to the gym wearing bin bag, t shirt, jumper, wooly hat (fluid loss = weight reduction) then training for around 80mins. If I don't drink after the run I always get cramps in the calves (sometime hamstrings as well) at around the 60min mark.
Never cramp in an un-fatigued/dehydrated state though.

Not at all usefull as an reply to your post but just showing you can reproduce EAMC's. Not very ethical way of doing it though :)

NewsBot · Jun 17, 2013

Predictors of calf cramping in rugby league
Summers, Katherine M. BPhysio(Hons); Snodgrass, Suzanne J. PhD; Callister, Robin PhD
Journal of Strength & Conditioning Research: 14 June 2013

Exercise-Associated Muscle Cramps (EAMC) in the calf are common in rugby league. To date, the aetiology and predictors of calf cramping are poorly understood. The aim of this study was to undertake a prospective investigation to identify predictors of calf cramping in rugby league players. Demographic and anthropometric data, as well as calf cramp and injury history, were collected in the preseason. Hydration status, number of games played and calf cramps were recorded on game days. Male rugby league players (n = 103, mean age 18.8 +/- 4.1 years) were classified as either EAMC (experienced at least one incident of calf cramps in the season) or no EAMC (no calf cramps). The following were investigated as possible predictors of EAMC using logistic regression modelling: competition level, age, ethnicity, playing position, history of cramping, pre-cramping, low back pain, foot orthotic usage, foot posture, foot strike, muscle flexibility, calf girth, hydration status and number of games played. Half the players, n = 52, experienced at least one incidence of calf cramping. Playing in a senior competition level (OR 0.21; 95% CI 0.06,0.75; p= 0.016), a history of calf cramping (10.85; 2.16,54.44; p=0.004) and a history of low back pain resulting in missed field minutes (4.50, 1.37,14.79; p=0.013) were found to predict EAMC. This study suggests that there is a high incidence of calf cramping in rugby league, especially at senior competition levels, and supports pre-season screening in senior players to identify those at risk of calf cramping and the development of possible preventative strategies.
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NewsBot · Jul 22, 2015

Good blog post:
Exercise-Associated Muscle Cramps: Causes, Prevention, And Treatment

NewsBot · Nov 15, 2015

Have We Discovered a Cure for Muscle Cramps?
A Nobel Prize–winning neuroscientist and a Harvard neurobiologist think they’ve discovered the antidote

NewsBot · Feb 2, 2017

NOVEL DIRECT AND INDIRECT EFFECTS OF RISK FACTORS FOR EXERCISE ASSOCIATED MUSCLE CRAMPING (EAMC) IN A COHORT OF 41 698 DISTANCE RUNNERS
Esmè Jordaan, Martin Schwellnus
Br J Sports Med 2017;51:337 doi:10.1136/bjsports-2016-097372.136

Background We recently identified novel risk factors for EAMC in distance runners, including age, gender, racing distance, a history of chronic diseases, medication, training and competition load, and running injuries. The relationships between these risk factors for EAMC are over-simplified, and complex path relationships between these risk factors and EAMC have not been investigated.

Objective The objective of the analysis was to explore the complex relationships among the risk factors associated with EAMC by means of path analysis, in order to estimate direct as well as indirect path relationships between the risk factors and EAMC. In addition, we sought to explore total effects by aggregating the direct and indirect effects.

Design and Settings 41 698 runners (21 km and 56 km), who were part of a 2-year prospective cohort study.

Type of Study Path analysis of prospective data.

Main Outcome Measurements Indirect, direct and total path estimates of the predictors of EAMC in distance runners.

Results Body Mass Index (BMI) and age were significant indirect predictors of EAMC (p<0.0001), while training and competition load, a history of chronic disease, medication use for chronic disease, and a history of running injuries were significant direct predictors for EAMC (p<0.0001). Gender was a significant direct as well as indirect predictor of EAMC (P<0.0001) and thus the total effect gives the overall impact of gender as a predictor of EAMC.

Conclusions Using a path analysis approach, novel risk factors for EAMC (indirect and direct relationships) were identified, indicating that the risk factors associated with EAMC are complex. Indirect risk factors do not impact directly on EAMC, but rather through their effects on direct risk factors. These data enable clinicians to better understand these complex relationships of risk factors and can apply this to knowledge in the prevention, diagnosis and management of EAMC in athletes.
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NewsBot · Nov 7, 2019

Muscle Cramping During Exercise: Causes, Solutions, and Questions Remaining
Ronald J. Maughan Susan M. Shirreffs
Sports Medicine: 06 November 2019

Muscle cramp is a temporary but intense and painful involuntary contraction of skeletal muscle that can occur in many different situations. The causes of, and cures for, the cramps that occur during or soon after exercise remain uncertain, although there is evidence that some cases may be associated with disturbances of water and salt balance, while others appear to involve sustained abnormal spinal reflex activity secondary to fatigue of the affected muscles. Evidence in favour of a role for dyshydration comes largely from medical records obtained in large industrial settings, although it is supported by one large-scale intervention trial and by field trials involving small numbers of athletes. Cramp is notoriously unpredictable, making laboratory studies difficult, but experimental models involving electrical stimulation or intense voluntary contractions of small muscles held in a shortened position can induce cramp in many, although not all, individuals. These studies show that dehydration has no effect on the stimulation frequency required to initiate cramping and confirm a role for spinal pathways, but their relevance to the spontaneous cramps that occur during exercise is questionable. There is a long history of folk remedies for treatment or prevention of cramps; some may reduce the likelihood of some forms of cramping and reduce its intensity and duration, but none are consistently effective. It seems likely that there are different types of cramp that are initiated by different mechanisms; if this is the case, the search for a single strategy for prevention or treatment is unlikely to succeed.
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NewsBot · Feb 3, 2020

Muscle Cramping During Exercise: Causes, Solutions, and Questions Remaining

NewsBot · Jun 14, 2020

Serum electrolyte concentrations and hydration status are not associated with exercise associated muscle cramping (EAMC) in distance runners FREE
M P Schwellnus et al
British Journal of Sports Medicine 2004;38:488-492.

Objectives: To determine whether acute exercise associated muscle cramping (EAMC) in distance runners is related to changes in serum electrolyte concentrations and hydration status.

Methods: A cohort of 72 runners participating in an ultra-distance road race was followed up for the development of EAMC. All subjects were weighed before and immediately after the race. Blood samples were taken before the race, immediately after the race, and 60 minutes after the race. Blood samples were analysed for glucose, protein, sodium, potassium, calcium, and magnesium concentrations, as well as serum osmolality, haemoglobin, and packed cell volume. Runners who suffered from acute EAMC during the race formed the cramp group (cramp, n = 21), while runners with no history of EAMC during the race formed the control group (control, n = 22).

Results: There were no significant differences between the two groups for pre-race or post-race body weight, per cent change in body weight, blood volume, plasma volume, or red cell volume. The immediate post-race serum sodium concentration was significantly lower (p = 0.004) in the cramp group (mean (SD), 139.8 (3.1) mmol/l) than in the control group (142.3 (2.1) mmol/l). The immediate post-race serum magnesium concentration was significantly higher (p = 0.03) in the cramp group (0.73 (0.06) mmol/l) than in the control group (0.67 (0.08) mmol/l).

Conclusions: There are no clinically significant alterations in serum electrolyte concentrations and there is no alteration in hydration status in runners with EAMC participating in an ultra-distance race.
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NewsBot · Aug 13, 2020

Muscle Cramping in the marathon: Dehydration and electrolyte depletion vs. muscle damage.
Martínez-Navarro, I, Montoya-Vieco, A, Collado, E, Hernando, B, Panizo, N, and Hernando, C.
J Strength Cond Res XX(X): 000–000, 2020—

Our aim was to compare dehydration variables, serum electrolytes, and muscle damage serum markers between runners who suffered exercise-associated muscle cramps (EAMC) and runners who did not suffer EAMC in a road marathon. We were also interested in analyzing race pacing and training background. Nighty-eight marathoners took part in the study. Subjects were subjected to a cardiopulmonary exercise test. Before and after the race, blood and urine samples were collected and body mass (BM) was measured. Immediately after the race EAMC were diagnosed. Eighty-eight runners finished the marathon, and 20 of them developed EAMC (24%) during or immediately after the race. Body mass change, post-race urine specific gravity, and serum sodium and potassium concentrations were not different between crampers and noncrampers. Conversely, runners who suffered EAMC exhibited significantly greater post-race creatine kinase (464.17 ± 220.47 vs. 383.04 ± 253.41 UI/L, p = 0.034) and lactate dehydrogenase (LDH) (362.27 ± 72.10 vs. 307.87 ± 52.42 UI/L, p = 0.002). Twenty-four hours post-race also values of both biomarkers were higher among crampers (CK: 2,438.59 ± 2,625.24 vs. 1,166.66 ± 910.71 UI/L, p = 0.014; LDH: 277.05 ± 89.74 vs. 227.07 ± 37.15 UI/L, p = 0.021). The difference in the percentage of runners who included strength conditioning in their race training approached statistical significance (EAMC: 25%, non-EAMC: 47.6%; p = 0.074). Eventually, relative speed between crampers and noncrampers only differed from the 25th km onward (p < 0.05). Therefore, runners who suffered EAMC did not exhibit a greater degree of dehydration and electrolyte depletion after the marathon but displayed significantly higher concentrations of muscle damage biomarkers.
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NewsBot · Sep 5, 2020

The Enduring Mystery of Muscle Cramps

A new study suggests that strength training is more important than electrolytes for preventing cramps

NewsBot · Sep 5, 2020

NewsBot said: ↑

The Enduring Mystery of Muscle Cramps

A new study suggests that strength training is more important than electrolytes for preventing cramps
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Muscle Cramping in the Marathon: Dehydration and Electrolyte Depletion vs. Muscle Damage
Ignacio Martínez-Navarro et al
J Strength Cond Res. 2020 Aug 12

Our aim was to compare dehydration variables, serum electrolytes, and muscle damage serum markers between runners who suffered exercise-associated muscle cramps (EAMC) and runners who did not suffer EAMC in a road marathon. We were also interested in analyzing race pacing and training background. Nighty-eight marathoners took part in the study. Subjects were subjected to a cardiopulmonary exercise test. Before and after the race, blood and urine samples were collected and body mass (BM) was measured. Immediately after the race EAMC were diagnosed. Eighty-eight runners finished the marathon, and 20 of them developed EAMC (24%) during or immediately after the race. Body mass change, post-race urine specific gravity, and serum sodium and potassium concentrations were not different between crampers and noncrampers. Conversely, runners who suffered EAMC exhibited significantly greater post-race creatine kinase (464.17 ± 220.47 vs. 383.04 ± 253.41 UI/L, p = 0.034) and lactate dehydrogenase (LDH) (362.27 ± 72.10 vs. 307.87 ± 52.42 UI/L, p = 0.002). Twenty-four hours post-race also values of both biomarkers were higher among crampers (CK: 2,438.59 ± 2,625.24 vs. 1,166.66 ± 910.71 UI/L, p = 0.014; LDH: 277.05 ± 89.74 vs. 227.07 ± 37.15 UI/L, p = 0.021). The difference in the percentage of runners who included strength conditioning in their race training approached statistical significance (EAMC: 25%, non-EAMC: 47.6%; p = 0.074). Eventually, relative speed between crampers and noncrampers only differed from the 25th km onward (p < 0.05). Therefore, runners who suffered EAMC did not exhibit a greater degree of dehydration and electrolyte depletion after the marathon but displayed significantly higher concentrations of muscle damage biomarkers.
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Damien Howell · Oct 2, 2020

Martinez-Navaro and colleagues suggest that strengthening exercises has a beneficial effect and can decrease the frequency of exercise associated muscle cramps (EAMC). The abstract reports the difference in the percentage of runners who included strength conditioning in their race training was 22% less EAMC. The abstract does not describe what “strength conditioning” included. Behringer and colleagues suggest the strength training should position the muscle in a short or slackened position. I have written a blog article entitled "Potential Prevention Strategy for Exercise Associated Muscle Cramps" suggesting a potential working hypothesis is If the muscles at risk of experiencing EAMC perform regular isometric strengthening exercise with the muscle in a position of active insufficiency (slackened length position), then it will decrease the likelihood of EAMC. This deserves investigation.

NewsBot · Nov 2, 2020

Exercise-Associated Muscle Cramps

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