Does Prophylactic Stretching Reduce the Occurrence of Exercise-Associated Muscle Cramping? A Critically Appraised Topic.

CLINICAL SCENARIO: Exercise-associated muscle cramps (EAMC) are sudden, painful, and involuntary contractions of skeletal muscles during or after physical activity. The best treatment for EAMC is gentle static stretching until abatement. Stretching is theorized to relieve EAMC by normalizing alpha motor neuron control, specifically by increasing Golgi tendon organ activity, and physically separating contractile proteins. However, it is unclear if stretching or flexibility training prevents EAMC via the same mechanisms. Despite this, many clinicians believe prophylactic stretching prevents EAMC occurrence. CLINICAL QUESTION: Do athletes who experience EAMC during athletic activities perform less prophylactic stretching or flexibility training than athletes who do not develop EAMC during competitions? SUMMARY OF KEY FINDINGS: In 3 cohort studies and 1 case-control study, greater preevent muscle flexibility, stretching, or flexibility training (ie, duration, frequency) was not predictive of who developed EAMC during competition. In one study, athletes who developed EAMC actually stretched more often and 9 times longer (9.8 [23.8] min/wk) than noncrampers (1.1 [2.5] min/wk). CLINICAL BOTTOM LINE: There is minimal evidence that the frequency or duration of prophylactic stretching or flexibility training predicts which athletes developed EAMC during competition. To more effectively prevent EAMC, clinicians should identify athletes' unique intrinsic and extrinsic risk factors and target those risk factors with interventions. STRENGTH OF RECOMMENDATION: Minimal evidence from 3 prospective cohort studies and 1 case-control study (mostly level 3 studies) that suggests prophylactic stretching or flexibility training can predict which athletes develop EAMC during athletic competitions.

Patient-Reported Prevalence, Characteristics, and Impact of Leg Cramps in an Urban Primary Care Clinic.

This study addresses the prevalence and characteristics of leg cramps in 294 primary care patients (mean age = 46.5 years), with 51.7% reporting leg cramps. Patients who experience resting or exercise-induced leg cramps were more likely to be older and female. Cramp severity averaged 5.6 on a scale of 1-10 and disturbed sleep "sometimes" or "often" in 55% of patients. Most patients did not discuss cramps with their clinician. Our study reveals a possible shift in patients who experience leg cramps to younger age and chronicity. Resting leg cramps should be reviewed by clinicians as a symptom of declining health and advancing aging.

Males, Older Age, Increased Training, Chronic Diseases, Allergies, and History of Injury Are Independent Risk Factors Associated With a History of Exercise-Associated Muscle Cramping in Distance Runners in 76 654 Race Entrants - SAFER XXIX.

OBJECTIVE: To determine independent risk factors associated with a history of exercise-associated muscle cramps (hEAMCs) in distance runner race entrants in a community-based mass participation event. DESIGN: Cross-sectional study. SETTING: 2012 to 2015, Two Oceans marathon races (21.1 and 56 km), South Africa. PARTICIPANTS: Seventy six thousand six hundred fifty-four consenting race entrants. ASSESSMENT OF RISK FACTORS: Entrants completed an online prerace medical screening questionnaire as part of the entry process. In a multiple model, sex, age, training variables, history of chronic disease, allergies, and running injuries were included as potential factors associated with hEAMC in 21.1 and 56 km entrants. MAIN OUTCOME MEASURES: Prevalence (%) and prevalence ratios (PRs, 95% confidence intervals) are reported. RESULTS: Men ( P < 0.0001) and older age (>40 years, P < 0.0001) were significantly associated with hEAMC. Therefore, the model was adjusted for sex and age group and run separately for 21.1- and 56-km entrants. Specific independent risk factors associated with hEAMC in 21.1- and 56-km entrants were: a history of chronic diseases (21.1 km: PR = 1.9; 56 km: PR = 1.6; P < 0.0001), running injury in the last 12 months (21.1 km: PR = 1.7; 56 km: PR = 1.4; P < 0.0001), history of allergies (21.1 km: PR = 1.4; 56 km: PR = 1.2; P < 0.0001), and various training variables (PR = 1.0-1.1). CONCLUSION: In 21.1- and 56-km race entrants, independent risk factors associated with hEAMC were men, older age, longer race distances, training variables, chronic diseases, history of allergies, and history of a running injury in the past 12 months.

Muscle Cramps in Outpatients with Liver Diseases in Tokyo, Japan.

Background and Objectives: Muscle cramps are often observed in patients with liver diseases, especially advanced liver fibrosis. The exact prevalence of muscle cramps in outpatients with liver diseases in Japan is unknown. Patients and Methods: This study examined the prevalence of, and therapies for, muscle cramps in outpatients with liver diseases in Tokyo, Japan. A total of 238 outpatients with liver diseases were retrospectively examined. We investigated whether they had muscle cramps using a visual analog scale (VAS) (from 0, none, to 10, strongest), and also investigated their therapies. Results: Muscle cramps were observed in 34 outpatients with liver diseases (14.3%); their mean VAS score was 5.53. A multivariate analysis demonstrated that older age (equal to or older than 66 years) was the only significant factor as-sociated with muscle cramps. The prevalence of muscle cramps among patients with liver diseases seemed not to be higher. The problem was that only 11 (32.4%) of 34 outpatients received therapy for their muscle cramps. Conclusions: Only age is related to muscle cramps, which is rather weak, and it is possible that this common symptom may not be limited to liver disease patients.

Evaluation of the relationship between serum carnitine levels and intradialytic complications in children with kidney failure.

BACKGROUND: Carnitine plays a crucial role in the metabolism of fatty acids as well as energy production. Previous research has suggested a significant decrease in carnitine levels in patients with kidney failure and those undergoing hemodialysis. Therefore, we designed this study to assess the prevalence and characteristics of carnitine deficiency and its association with hemodialysis complications in the pediatric population. METHODS: This research was a pilot study of 29 children undergoing hemodialysis. Before hemodialysis, a 5-mL blood sample was drawn from each patient through a peripheral vein to measure serum-free carnitine levels, complete blood count with differential, blood urea nitrogen (BUN), creatinine, and electrolytes. Each patient was observed for intradialytic complications, including muscle cramps and hypotension, during 12 sessions of hemodialysis. RESULTS: We included 26 participants with a mean age of 14.23 years undergoing hemodialysis. Carnitine deficiency was revealed in 54.8% of our participants. Also, there was no significant correlation between carnitine deficiency and age, gender, and BUN levels (P = 0.698, P = 0.43, and P > 0.05, respectively). Intradialytic complications, including episodes of hypotension and muscle cramps, were more frequent in patients with carnitine deficiency (P = 0.02, P = 0.01, respectively). Other reasons for muscle cramps, such as fluid overload, nutritional status, dialysis regimen, and other important lab results (phosphorus, magnesium, etc.), were ruled out. CONCLUSION: In conclusion, we found a higher prevalence of carnitine deficiency in pediatric hemodialysis patients. Carnitine deficiency was significantly associated with increased intradialytic symptoms, including muscle spasms and hypotension. Our results could support a potential role of carnitine supplementation in pediatric patients with kidney failure for controlling intradialytic complications, but this requires further investigation. A higher resolution version of the Graphical abstract is available as Supplementary information.

Prevalence, Clinical Characteristics, and Self-Reported Treatment of Exercise-Associated Muscle Cramping Differ Between 21.1- and 56-Km Running Race Entrants-SAFER XXII.

OBJECTIVE: To determine whether the lifetime prevalence and clinical characteristics of exercise-associated muscle cramping (EAMC) differ between runners entering a 21.1- versus 56-km road race. DESIGN: Cross-sectional study. SETTING: The 2012 to 2015 Two Oceans Marathon races (21.1 and 56 km), South Africa. PARTICIPANTS: Participants were consenting race entrants (21.1 km = 44 458; 56 km = 26 962) who completed an online prerace medical screening questionnaire. INDEPENDENT VARIABLE: A history of EAMC. MAIN OUTCOME MEASURES: The main outcome variables were lifetime prevalence (%) and clinical characteristics (muscle groups affected, timing of occurrence, severity, frequency of serious EAMC, and self-reported treatment) of a history of EAMC. Differences between 56- and 21.1-km race entrants were explored (relative risk [RR]). RESULTS: The lifetime prevalence of EAMC was 12.8%, which was higher in 56- (20.0%; 95% CI 19.5-20.6) versus 21.1-km race entrants (8.5%; 8.2-8.8) ( P = 0.0001). In all entrants, the fourth quarter was the most common onset (46.4%), calf muscles were the most commonly affected (53.1%), and most EAMCs were of mild-to-moderate severity (95%). In 56- versus 21.1-km entrants, hamstring (RR = 1.7; 1.5-1.9) and quadriceps muscle groups (RR = 1.5; 1.3-1.7) were more frequently affected ( P = 0.0001), the onset of EAMC during racing was less common in the first quarter (RR = 0.3; 0.2-0.4) ( P = 0.0001), and serious EAMC was more frequent (RR = 1.6; 1.4-1.9) ( P = 0.0001). CONCLUSIONS: In 56- versus 21.1-km runners, a history of EAMC is 2 times more frequent and muscle groups affected, onset in a race, and severity of EAMC differed. The lifetime prevalence was lower than previously reported in other events. Risk factors associated with EAMC may differ between entrants for different race distances.

Predictors of Intradialytic Symptoms: An Analysis of Data From the Hemodialysis Study.

BACKGROUND: Most patients receiving maintenance hemodialysis (HD) experience adverse symptoms, which are associated with decreased quality of life. Despite decades of experience, our understanding of causes of HD symptoms remains limited. We aimed to identify modifiable patient- and HD-related predictors of intradialytic symptoms. STUDY DESIGN: Prospective cohort. SETTING & PARTICIPANTS: We leveraged patient-level (n=1,838) and HD session-level (n=64,797) data from the Hemodialysis Trial. EXPOSURE: Pre-HD serum urea nitrogen (SUN) level, pre-HD systolic blood pressure (SBP), intradialytic SBP decline, and ultrafiltration rate (UFR). OUTCOMES: Intra-HD symptoms, including cramps, nausea, chest pain, headache, and lightheadedness. ANALYTICAL APPROACH: Random-effects logistic regression models. RESULTS: Overall, symptoms occurred in 10.7% of HD sessions. Higher pre-HD SUN level (per 10 mg/dL) was associated with higher adjusted odds of muscle cramping and lightheadedness (adjusted ORs [aORs] of 1.20 [95% CI, 1.17-1.22] and 1.13 [95% CI, 1.08-1.18], respectively). SBP decline (from the predialysis value to the dialysis session nadir, per each 10-mm Hg decrease) was associated with greater risk for muscle cramping, headache, chest pain, vomiting, and lightheadedness (the largest aORs were for the 2 latter symptoms: 1.24 [95% CI, 1.20-1.28] and 1.37 [95% CI, 1.33-1.42], respectively). Higher UFR (per 1 mL/kg/h) was associated with greater odds of cramping (aOR, 1.03; 95% CI, 1.02-1.03). Conversely, higher pre-HD SBP (per 10 mm Hg) was associated with reduced risk for vomiting (aOR, 0.88; 95% CI, 0.85-0.92) and lightheadedness (aOR, 0.82; 95% CI, 0.80-0.85). LIMITATIONS: Measured osmolality, dialysate prescription data, and time stamps for symptom occurrence were not available. Clinical trial data may not be broadly generalizable. CONCLUSIONS: Higher pre-HD SUN level, UFR, pre-HD SBP, and SBP decline are independently associated with different patterns of adverse intradialytic symptoms. Recognition that different symptoms may have variable causes may allow tailoring of personalized treatments in future interventional studies.

Low dialysate sodium levels for chronic haemodialysis.

BACKGROUND: Cardiovascular (CV) disease is the leading cause of death in dialysis patients, and strongly associated with fluid overload and hypertension. It is plausible that low dialysate [Na+] may decrease total body sodium content, thereby reducing fluid overload and hypertension, and ultimately reducing CV morbidity and mortality. OBJECTIVES: This review evaluated harms and benefits of using a low (< 138 mM) dialysate [Na+] for maintenance haemodialysis (HD) patients. SEARCH METHODS: We searched the Cochrane Kidney and Transplant Register of Studies up to 7 August 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. SELECTION CRITERIA: Randomised controlled trials (RCTs), both parallel and cross-over, of low (< 138 mM) versus neutral (138 to 140 mM) or high (> 140 mM) dialysate [Na+] for maintenance HD patients were included. DATA COLLECTION AND ANALYSIS: Two investigators independently screened studies for inclusion and extracted data. Statistical analyses were performed using random effects models, and results expressed as risk ratios (RR) for dichotomous outcomes, and mean differences (MD) or standardised MD (SMD) for continuous outcomes, with 95% confidence intervals (CI). Confidence in the evidence was assessed using GRADE. MAIN RESULTS: We included 12 studies randomising 310 patients, with data available for 266 patients after dropout. All but one study evaluated a fixed concentration of low dialysate [Na+], and one profiled dialysate [Na+]. Three studies were parallel group, and the remaining nine cross-over. Of the latter, only two used a washout between intervention and control periods. Most studies were short-term with a median (interquartile range) follow-up of 3 (3, 8.5) weeks. Two were of a single HD session, and two of a single week's HD. Half of the studies were conducted prior to 2000, and five reported use of obsolete HD practices. Risks of bias in the included studies were often high or unclear, lowering confidence in the results.Compared to neutral or high dialysate [Na+], low dialysate [Na+] had the following effects on "efficacy" endpoints: reduced interdialytic weight gain (10 studies: MD -0.35 kg, 95% CI -0.18 to -0.51; high certainty evidence); probably reduced predialysis mean arterial blood pressure (BP) (4 studies: MD -3.58 mmHg, 95% CI -5.46 to -1.69; moderate certainty evidence); probably reduced postdialysis mean arterial BP (MAP) (4 studies: MD -3.26 mmHg, 95% CI -1.70 to -4.82; moderate certainty evidence); probably reduced predialysis serum [Na+] (7 studies: MD -1.69 mM, 95% CI -2.36 to -1.02; moderate certainty evidence); may have reduced antihypertensive medication (2 studies: SMD -0.67 SD, 95% CI -1.07 to -0.28; low certainty evidence). Compared to neutral or high dialysate [Na+], low dialysate [Na+] had the following effects on "safety" endpoints: probably increased intradialytic hypotension events (9 studies: RR 1.56, 95% 1.17 to 2.07; moderate certainty evidence); probably increased intradialytic cramps (6 studies: RR 1.77, 95% 1.15 to 2.73; moderate certainty evidence).Compared to neutral or high dialysate [Na+], low dialysate [Na+] may make little or no difference to: intradialytic BP (2 studies: MD for systolic BP -3.99 mmHg, 95% CI -17.96 to 9.99; diastolic BP 1.33 mmHg, 95% CI -6.29 to 8.95; low certainty evidence); interdialytic BP (2 studies:, MD for systolic BP 0.17 mmHg, 95% CI -5.42 to 5.08; diastolic BP -2.00 mmHg, 95% CI -4.84 to 0.84; low certainty evidence); dietary salt intake (2 studies: MD -0.21g/d, 95% CI -0.48 to 0.06; low certainty evidence).Due to very low quality of evidence, it is uncertain whether low dialysate [Na+] changed extracellular fluid status, venous tone, arterial vascular resistance, left ventricular mass or volumes, thirst or fatigue. Studies did not examine cardiovascular or all-cause mortality, cardiovascular events, or hospitalisation. AUTHORS' CONCLUSIONS: It is likely that low dialysate [Na+] reduces intradialytic weight gain and BP, which are effects directionally associated with improved outcomes. However, the intervention probably also increases intradialytic hypotension and reduces serum [Na+], effects that are associated with increased mortality risk. The effect of the intervention on overall patient health and well-being is unknown. Further evidence is needed in the form of longer-term studies in contemporary settings, evaluating end-organ effects in small-scale mechanistic studies using optimal methods, and clinical outcomes in large-scale multicentre RCTs.

Relationship of muscle cramps to quality of life and sleep disturbance in patients with chronic liver diseases: A nationwide study.

BACKGROUND & AIMS: Although muscle cramps frequently occur in patients with cirrhosis, the importance of muscle cramps remains unclear. The aims of this study were to investigate the relationship of muscle cramps with quality of life (QOL) and sleep disturbance. In addition, this multi-institutional collaborative study in Japan investigated factors associated with muscle cramps in patients with cirrhosis. METHODS: A total of 1788 patients with chronic liver diseases including both non-cirrhosis and cirrhosis completed a questionnaire survey investigating: (i) frequency of muscle cramps, (ii) relationship of muscle cramps to poor QOL and sleep disturbance, (iii) characteristics of patients who require therapeutic intervention and (iv) characteristics of patients prone to experiencing muscle cramps. RESULTS: This study revealed that 51.8% of patients with cirrhosis have experienced muscle cramps. People who experienced muscle cramps were more likely to have reduced QOL and sleep disturbance if muscle cramps had (i) high frequency (occurring daily to a few times per week, P < .01); (ii) long duration (between a few minutes and a few hours, P < .01) and (iii) intense severity (visual analogue scale ≥4, P < .01). Age, female sex, positive results for hepatitis C virus, low serum albumin concentration, and cirrhosis were independent factors related to the severity of muscle cramps. CONCLUSION: Muscle cramps occurred with great frequency and were associated with various factors such as age, sex, hepatitis C virus and liver function. Many patients experience poor QOL (26.3%) due to muscle cramps, and therapeutic interventions are therefore needed.

Metformin's impact on statin-associated muscle symptoms: An analysis of ACCORD study data and research materials from the NHLBI Biologic Specimen and Data Repository Information Coordinating Center.

Statins are widely prescribed, yet statin muscle pain limits their use, leading to increased cardiovascular risk. No validated therapy for statin muscle pain exists. The goal of the study was to assess whether metformin was associated with reduced muscle pain. A secondary analysis of data from the ACCORD trial was performed. An ACCORD sub-study assessed patients for muscle cramps and leg/calve pain while walking, typical non-severe statin muscle pain symptoms. We compared muscle pain between patients using a statin (n = 445) or both a statin and metformin (n = 869) at baseline. Overall patient characteristics were balanced between groups. Unadjusted analysis showed fewer reports of muscle cramps (35%) and leg/calve pain while walking (40%) with statins and metformin compared to statin only (muscle cramps, 42%; leg/calve pain while walking, 47%). Multivariable regression demonstrated a 22% odds reduction for muscle cramps (P = 0.049) and a 29% odds reduction for leg/calve pain while walking (P = 0.01). Metformin appears to reduce the risk of non-severe statin muscle pain and additional research is needed to confirm the findings and assess metformin's impact on statin adherence and related cardiovascular outcomes.

Prevalence, correlates and impact of pain and cramps in anti-MAG neuropathy: a multicentre European study.

BACKGROUND AND PURPOSE: The frequency of pain and cramps is uncertain in anti-myelin associated glycoprotein antibody (anti-MAG) neuropathy. Whether these symptoms may affect function/quality of life is unknown. METHODS: A cross-sectional study of the prevalence, correlates and impact of pain, pain subtypes and cramps, their severity, frequency and anatomical distribution was performed for 55 clinically stable patients with anti-MAG neuropathy. RESULTS: Pain of any type was reported by 80% of subjects. The most common subtype was paraesthesiae and dysaesthesiae (70%). Cramps were reported by >60% of patients, with lower limb cramps in all and upper limb cramps in about 20%. Cramps affected daily activities in >30% of these subjects, sleep in 60%, ability to exercise in >30%. Total pain score correlated with several Short Form 36 health-related quality of life (SF-36 HR-QoL) measures (P < 0.05), with Inflammatory Rasch-built Overall Disability Scale (I-RODS) (P = 0.006) and 10-m timed walk (P = 0.019). An independent association was ascertained with I-RODS (P = 0.002). Different pain subtypes showed multiple associations with SF-36 HR-QoL measures and/or functional scales. Upper limb cramps had multiple SF-36 HR-QoL functional correlates, with an independent association with the Overall Neuropathy Limitation Score (ONLS) (P = 0.004). Cramp severity correlated with ONLS (P = 0.04) and I-RODS (P = 0.028) and inversely with level of physiotherapy input (P = 0.009). Cramp frequency was associated with tremor score (P = 0.004) and multiple SF-36 HR-QoL subsections. CONCLUSIONS: Neuropathic pain and cramps may affect function and quality of life in anti-MAG neuropathy. Optimizing treatments of these symptoms, including by adequate levels of physiotherapy, may be beneficial in affected patients and requires further research.

Underlying Chronic Disease, Medication Use, History of Running Injuries and Being a More Experienced Runner Are Independent Factors Associated With Exercise-Associated Muscle Cramping: A Cross-Sectional Study in 15778 Distance Runners.

BACKGROUND: Exercise-associated muscle cramping (EAMC) is a significant medical complication in distance runners, yet factors associated with EAMC are poorly documented. OBJECTIVE: To document risk factors associated with EAMC in runners. DESIGN: Cross-sectional study. SETTING: Two ocean races (21.1 km, and 56 km). PARTICIPANTS: Fifteen thousand seven hundred seventy-eight race entrants. METHODS: Participants completed a prerace medical history screening tool including: training, cardiovascular disease (CVD), risk factors for, and symptoms of CVD, history of diseases affecting major organ systems, cancer, allergies, medication use, and running injury. Runners were grouped as having a history of EAMC (hEAMC group = 2997) and a control group (Control = 12 781). RESULTS: Independent factors associated with a higher prevalence ratio (PR) of hEAMC were any risk factor for CVD (PR = 1.16; P = 0.0002), symptoms of CVD (PR = 2.38; P < 0.0001), respiratory disease (PR = 1.33; P < 0.0001), gastrointestinal disease (PR = 1.86; P < 0.0001), nervous system or psychiatric disease (PR = 1.51; P < 0.0001), kidney or bladder disease, (PR = 1.60; P < 0.0001), haematological or immune disease (PR = 1.54; P = 0.0048), cancer (PR = 1.34; P = 0.0031), allergies (PR = 1.37; P < 0.0001), regular medication use (PR = 1.80; P < 0.0001), statin use (PR = 1.26; P = 0.0127), medication use during racing (PR = 1.88; P < 0.0001), running injury (PR = 1.66; P < 0.0001), muscle injury (PR = 1.82; P < 0.0001), tendon injury (PR = 1.62; P < 0.0001), and runners in the experienced category (PR = 1.22; P < 0.0001). CONCLUSION: Novel risk factors associated with EAMC in distance runners were underlying chronic disease, medication use, a history of running injuries, and experienced runners. These factors must be identified as possible associations, and therefore be considered in the diagnosis and treatment of EAMC.

Injury and illness in aquatic sport: how high is the risk? A comparison of results from three FINA World Championships.

BACKGROUND: Epidemiological information on injury/illness is required to develop effective injury prevention strategies. AIM: To assess the frequency and characteristics of injuries/illnesses (1) in the 4 weeks prior to and (2) during the Fédération Internationale de Natation (FINA) World Championships 2015 compared with 2013 and 2009. METHOD: (1) Athletes answered a retrospective questionnaire, and (2) the medical staff reported injuries/illnesses prospectively during the championships. RESULTS: (1) A quarter of responding athletes reported symptoms in the 4 weeks prior to the championships. More than half of all affected athletes presented with substantial severity, 80% took medication, 70% had overuse injuries and 30% did not modify their training regime despite symptoms. At the start of the championships, 70% of affected participants were still symptomatic. (2) During the championships, injury and illness incidence was 12.9 per 100 athletes. The most common injuries were shoulder sprains (5.7%) and muscle cramps of the lower back (5.7%). The most common illnesses were infections of the respiratory (33.9%) and gastrointestinal tract (23.5%). Risk factors included discipline and age, but not gender. Incidence was highest in athletes competing in high diving (HD), water polo (WP) and diving (DIV) for injuries, and WP and swimming (SW) for illnesses. The significantly higher incidence of injuries and illnesses at the FINA World Championships 2015 compared with 2013 and 2009 was most probably due to a similarly improved response rate of the medical staff. CONCLUSIONS: In aquatic sports, surveillance and health promotion should focus on prevention of out-of-competition overuse injuries and athlete education.

A narrative review of exercise-associated muscle cramps: Factors that contribute to neuromuscular fatigue and management implications.

Although exercise-associated muscle cramps (EAMC) are highly prevalent among athletic populations, the etiology and most effective management strategies are still unclear. The aims of this narrative review are 3-fold: (1) briefly summarize the evidence regarding EAMC etiology; (2) describe the risk factors and possible physiological mechanisms associated with neuromuscular fatigue and EAMC; and (3) report the current evidence regarding prevention of, and treatment for, EAMC. Based on the findings of several large prospective and experimental investigations, the available evidence indicates that EAMC is multifactorial in nature and stems from an imbalance between excitatory drive from muscle spindles and inhibitory drive from Golgi tendon organs to the alpha motor neurons rather than dehydration or electrolyte deficits. This imbalance is believed to stem from neuromuscular overload and fatigue. In concert with these findings, the most successful treatment for an acute bout of EAMC is stretching, whereas auspicious methods of prevention include efforts that delay exercise-induced fatigue. Muscle Nerve 54: 177-185, 2016.

Natural history of muscle cramps in amyotrophic lateral sclerosis.

INTRODUCTION: Muscle cramping is a common symptom in amyotrophic lateral sclerosis (ALS) that lacks efficacious treatment. The natural history of this symptom is unknown, which hampers efforts to design optimal clinical trials. METHODS: We surveyed early stage ALS patients about their experience with cramps each month by phone for up to 21 months. RESULTS: Cramps developed in 95% of patients over the course of their disease. The number of cramps experienced by an individual varied widely from month-to-month and trended lower after the first year of illness (P = 0.26). Those with limb-onset and age >60 years had more cramps than bulbar-onset (P < 0.0001) and younger patients (P < 0.0001). CONCLUSIONS: The high variability of the number of cramps experienced suggests that clinical trials will need to use crossover designs or large numbers of participants, even when the treatment effect is substantial.

Prevalence of cramps in patients over the age of 60 in primary care : a cross sectional study.

BACKGROUND: Cramps are involuntary painful muscle contractions that mainly affect older people. Cramps may cause severe pain and sleep disturbance. Little information exists on the prevalence and the main features of cramps in primary care settings. The objective of this study was to estimate the prevalence and the main features of cramps among primary care patients aged 60 years and older. METHODS: We prospectively enrolled 516 patients aged 60 years and older in a cross-sectional study at 25 general practices in Alsace - France between October 2011 and March 2012. Questionnaires were used to obtain information about demographics, cramp presence and main features, medical history, and treatment. RESULTS: The adjusted prevalence was 46 % (95 % CI: 38-53 %). Thirty-one per cent of the study sample reported being woken up by cramps, 15 % had cramps more than 3 times a month. Logistic regression revealed a slightly higher prevalence in the age group 65-69 years compared to 60-64 years. No significant association was observed between other age groups and prevalence, or between gender and prevalence. The main localization of cramps was in the calves (80 %). The duration since onset was 5 years or more for 58 %. CONCLUSIONS: Cramps are common in primary care, and although only a minority of patients report suffering from cramps more than once a week, many patients report cramp-related sleep disturbance. Further studies are needed to assess risk factors and therapeutic options for patients suffering from cramps in primary care.

Does a Reduction in Serum Sodium Concentration or Serum Potassium Concentration Increase the Prevalence of Exercise-Associated Muscle Cramps?

CLINICAL SCENARIO: Although exercise-associated muscle cramps (EAMC) are common in ultradistance runners and athletes in general, their etiology remains unclear. EAMC are painful, sudden, involuntary contractions of skeletal muscle occurring during or after exercise and are recognized by visible bulging or knotting of the whole, or part of, a muscle. Many clinicians believe EAMC occur after an imbalance in electrolyte concentrations, specifically serum sodium concentration ([Na+]s) and serum potassium concentration ([K+]s). Studies that have established a link between EAMC occurrence and serum electrolyte concentrations after an athletic event are unhelpful. Focused Clinical Question: Are [Na+]s and [K+]s different in athletes who experience EAMC than noncrampers?

[What do we know about the exercise-related transient abdominal pain ?] / Que sait-on sur le « point de côté ¼ lié à l'effort ?

Exercise-related transient abdominal pain or « side stitch ¼ is a very common problem among athletes, whatever their level of participation. This pain may be present in different areas of the abdomen, even in the shoulder, usually well localized, and described as cramping or stabbing depending on the severity. The etiology is still debated, with many possible theories. It is a benign problem but other pathologies, often more severe, must be excluded in case of any atypical presentation. There are simple preventive measures recommended. This pain usually disappears within minutes by slowing or stopping the effort and / or using different methods without scientific validation until now.

La douleur abdominale transitoire liée à l'effort ou « point de côté ¼ est un problème fréquemment rencontré chez les sportifs, qu'ils soient débutants ou confirmés. Cette douleur peut être présente dans différentes zones de l'abdomen, voire même les épaules, le plus souvent bien localisée, décrite comme une crampe ou « coup de couteau ¼ selon la sévérité. L'étiologie est encore débattue, avec de multiples théories possibles. Il s'agit d'un problème bénin mais d'autres pathologies, souvent plus graves, doivent être exclues devant toute présentation atypique. Il existe des mesures préventives simples à conseiller. Cette douleur disparaît généralement en quelques minutes en ralentissant ou stoppant l'effort et / ou à l'aide de différentes méthodes, sans validation scientifique à ce jour.

Association of short-term bleeding and cramping patterns with long-acting reversible contraceptive method satisfaction.

OBJECTIVE: We sought to examine the short-term (3- and 6-month), self-reported bleeding and cramping patterns with intrauterine devices (IUDs) and the contraceptive implant, and the association of these symptoms with method satisfaction. STUDY DESIGN: We analyzed 3- and 6-month survey data from IUD and implant users in the Contraceptive CHOICE Project, a prospective cohort study. Participants who received a long-acting reversible contraceptive (LARC) method (levonorgestrel-releasing intrauterine system [LNG-IUS], copper IUD, or the etonogestrel implant) and completed their 3- and 6-month surveys were included. Univariable and multivariable analyses were performed to examine the association of bleeding and cramping patterns with short-term satisfaction. RESULTS: Our analytic sample included 5011 Contraceptive CHOICE Project participants: 3001 LNG-IUS users, 826 copper IUD users, and 1184 implant users. At 3 months, >65% of LNG-IUS and implant users reported no change or decreased cramping, while 63% of copper IUD users reported increased menstrual cramping. Lighter bleeding was reported by 67% of LNG-IUS users, 58% of implant users, and 8% of copper IUD users. Satisfaction of all LARC methods was high (≥90%). LARC users with increased menstrual cramping (relative risk adjusted [RRadj], 0.78; 95% confidence interval [CI], 0.72-0.85), heavier bleeding (RRadj, 0.83; 95% CI, 0.76-0.92), and increased bleeding frequency (RRadj, 0.73; 95% CI, 0.67-0.80) were less likely to report being very satisfied at 6 months. CONCLUSION: Regardless of the LARC method, satisfaction at 3 and 6 months is very high. Changes in self-reported bleeding and cramping are associated with short-term LARC satisfaction.

Effects of 100-km ultramarathon on acute kidney injury.

OBJECTIVE: To evaluate the prevalence and characteristics of acute kidney injury (AKI) in 100-km ultramarathon runners. DESIGN: Prospective observational study. SETTING: The 2011 Soochow University ultramarathon, in which each athlete ran for 100 km. PARTICIPANTS: All Taiwanese entrants who participated in the 100-km race and lived in the northern part of Taiwan were invited to participate in the study. MAIN OUTCOME MEASURES: Acute kidney injury was defined using the Acute Kidney Injury Network criteria. Blood and urine samples were collected 1 week before, immediately after, and 1 day after the race. RESULTS: Immediately after the race, 85% (22) of the 26 subjects were diagnosed with AKI, 65% (16) with moderate dehydration, 23% (6) with muscle cramps, and 12% (3) with hematuria. Body weight was significantly decreased from prerace to all postrace measurements. Plasma levels of potassium ion, creatinine, renin, and aldosterone were significantly elevated immediately after the race and then significantly reduced 1 day after the race. Changes in plasma levels of sodium, creatine kinase, and creatine kinase-MB, as well as urine potassium and creatinine, were indicative of AKI. CONCLUSIONS: Transient AKI and muscle cramps are very common in 100-km ultramarathon runners. All transient ultra-runners who developed AKI in this study recovered their renal function 1 day later. CLINICAL RELEVANCE: Ultramarathon running is associated with a wide range of significant changes in hematological parameters, several of which can be associated with potentially serious renal and physiological abnormalities.