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Eifling KP, Gaudio FG, Dumke C, Lipman GS, Otten EM, Martin AD, Grissom CK. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update. Wilderness Environ Med 2024; 35:112S-127S. [PMID: 38425235 DOI: 10.1177/10806032241227924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
The Wilderness Medical Society (WMS) convened an expert panel in 2011 to develop a set of evidence-based guidelines for the recognition, prevention, and treatment of heat illness. The current panel retained 5 original members and welcomed 2 new members, all of whom collaborated remotely to provide an updated review of the classifications, pathophysiology, evidence-based guidelines for planning and preventive measures, and recommendations for field- and hospital-based therapeutic management of heat illness. These recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks or burdens for each modality. This is an updated version of the WMS clinical practice guidelines for the prevention and treatment of heat illness published in Wilderness & Environmental Medicine. 2019;30(4):S33-S46.
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Affiliation(s)
- Kurt P Eifling
- Department of Emergency Medicine, University of Arkansas for Medical Sciences, Fayetteville, AR
| | - Flavio G Gaudio
- Department of Emergency Medicine, New York-Presbyterian Hospital / Weill Cornell Medical College, New York, NY
| | - Charles Dumke
- School of Integrative Physiology and Athletic Training, University of Montana, Missoula, MT
| | | | - Edward M Otten
- Department of Emergency Medicine, University of Cincinnati, Cincinnati, OH
| | - August D Martin
- Department of Internal Medicine, University of Arkansas for Medical Sciences, Fayetteville, AR
| | - Colin K Grissom
- Pulmonary and Critical Care Division, Intermountain Medical Center and the University of Utah, Salt Lake City, UT
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Szymanski M, Miller KC, O'Connor P, Hildebrandt L, Umberger L. Sweat Characteristics in Individuals With Varying Susceptibilities of Exercise-Associated Muscle Cramps. J Strength Cond Res 2022; 36:1171-1176. [PMID: 35482541 DOI: 10.1519/jsc.0000000000003605] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
ABSTRACT Szymanski, M, Miller, KC, O'Connor, P, Hildebrandt, L, and Umberger, L. Sweat characteristics in individuals with varying susceptibilities of exercise-associated muscle cramps. J Strength Cond Res 36(5): 1171-1176, 2022-Many medical professionals believe dehydration and electrolyte losses cause exercise-associated muscle cramping (EAMC). Unlike prior field studies, we compared sweat characteristics in crampers and noncrampers but accounted for numerous factors that affect sweat characteristics including initial hydration status, diet and fluid intake, exercise conditions, and environmental conditions. Sixteen women and 14 men (mean ± SD; age = 21 ± 2 year, body mass = 69.1 ± 11.6 kg, height = 171.4 ± 9.9 cm) self-reported either no EAMC history (n = 8), low EAMC history (n = 10), or high EAMC history (n = 12). We measured V̇o2max, and subjects recorded their diet. At least 3 days later, subjects ran at 70% of their V̇o2max for 30 minutes in the heat (39.9 ± 0.6° C, 36 ± 2% relative humidity). Dorsal forearm sweat was collected and analyzed for sweat sodium concentration ([Na+]sw), sweat potassium concentration ([K+]sw), and sweat chloride concentration ([Cl-]sw). Sweat rate (SWR) was estimated from body mass and normalized using body surface area (BSA). Dietary fluid, Na+, and K+ ingestion was estimated from a 3-day diet log. We observed no differences for any variable among the original 3 groups (p = 0.05-p = 0.73). Thus, we combined the high and low cramp groups and reanalyzed the data against the noncramping group. Again, there were no differences for [Na+]sw (p = 0.68), [K+]sw (p = 0.86), [Cl-]sw, (p = 0.69), SWR/BSA (p = 0.11), dietary Na+ (p = 0.14), dietary K+ (p = 0.66), and fluid intake (p = 0.28). Fluid and electrolyte losses may play a more minor role in EAMC genesis than previously thought.
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Affiliation(s)
- Michael Szymanski
- Central Michigan University, School of Rehabilitation and Medical Sciences, Mount Pleasant, Michigan
| | - Kevin C Miller
- Central Michigan University, School of Rehabilitation and Medical Sciences, Mount Pleasant, Michigan
| | - Paul O'Connor
- Central Michigan University, School of Health Sciences, Mount Pleasant, Michigan; and
| | - Leslie Hildebrandt
- Central Michigan University, College of Education and Human Services, Mount Pleasant, Michigan
| | - Leah Umberger
- Central Michigan University, School of Health Sciences, Mount Pleasant, Michigan; and
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Miller KC, McDermott BP, Yeargin SW, Fiol A, Schwellnus MP. An Evidence-Based Review of the Pathophysiology, Treatment, and Prevention of Exercise-Associated Muscle Cramps. J Athl Train 2022; 57:5-15. [PMID: 34185846 PMCID: PMC8775277 DOI: 10.4085/1062-6050-0696.20] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Exercise-associated muscle cramps (EAMCs) are common and frustrating for athletes and the physically active. We critically appraised the EAMC literature to provide evidence-based treatment and prevention recommendations. Although the pathophysiology of EAMCs appears controversial, recent evidence suggests that EAMCs are due to a confluence of unique intrinsic and extrinsic factors rather than a singular cause. The treatment of acute EAMCs continues to include self-applied or clinician-guided gentle static stretching until symptoms abate. Once the painful EAMCs are alleviated, the clinician can continue treatment on the sidelines by focusing on patient-specific risk factors that may have contributed to the onset of EAMCs. For EAMC prevention, clinicians should obtain a thorough medical history and then identify any unique risk factors. Individualizing EAMC prevention strategies will likely be more effective than generalized advice (eg, drink more fluids).
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Affiliation(s)
- Kevin C. Miller
- School of Rehabilitation and Medical Sciences, Central Michigan University, Mount Pleasant
| | - Brendon P. McDermott
- Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville
| | - Susan W. Yeargin
- Exercise Science Department, University of South Carolina, Columbia
| | - Aidan Fiol
- Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville
| | - Martin P. Schwellnus
- Institute for Sport, Exercise Medicine and Lifestyle Research, University of Pretoria, South Africa
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Abstract
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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Affiliation(s)
- Ronald J Maughan
- School of Medicine, St Andrews University, St Andrews, Scotland, UK.
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Lipman GS, Gaudio FG, Eifling KP, Ellis MA, Otten EM, Grissom CK. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2019 Update. Wilderness Environ Med 2019; 30:S33-S46. [DOI: 10.1016/j.wem.2018.10.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/04/2018] [Accepted: 10/22/2018] [Indexed: 10/26/2022]
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Miller KC, Long BC, Edwards JE. Muscle cramp susceptibility increases following a volitionally induced muscle cramp. Muscle Nerve 2017; 56:E95-E99. [PMID: 28063158 DOI: 10.1002/mus.25562] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 01/03/2017] [Accepted: 01/05/2017] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Muscle cramping may increase peripheral nervous system excitability. It is unknown if, and how long, cramp susceptibility is affected by previous cramping. We tested whether volitionally induced muscle cramps (VIMCs) lowered cramp threshold frequency (TFc ) and how long TFc was affected post-VIMC. METHODS Fifteen cramp-prone participants volitionally induced a flexor hallucis brevis (FHB) cramp on 4 separate days. FHB TFc was measured before VIMC (i.e., baseline) and 5, 30, and 60 min post-VIMC. VIMC electromyography (EMG) amplitude, VIMC duration, and perceived VIMC intensity were measured to ensure consistency of VIMC between days. RESULTS VIMC EMG amplitude, duration, and perceived intensity were similar between days (P > 0.05). VIMC lowered TFc ; baseline TFc (18 ± 6 Hz) was higher than 5-min (14 ± 6 Hz), 30-min (14 ± 5 Hz), and 60-min TFc (14 ± 5 Hz; P < 0.05). DISCUSSION Acute VIMCs increase cramp susceptibility. Clinicians should apply treatments for at least 60 min postcramp to decrease the probability of cramp recurrence. Muscle Nerve 56: E95-E99, 2017.
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Affiliation(s)
- Kevin C Miller
- Central Michigan University, School of Rehabilitation and Medical Sciences, 1208 Health Professions Building, Mount Pleasant, Michigan, USA
| | - Blaine C Long
- Central Michigan University, School of Rehabilitation and Medical Sciences, 1208 Health Professions Building, Mount Pleasant, Michigan, USA
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Lipman GS, Eifling KP, Ellis MA, Gaudio FG, Otten EM, Grissom CK. Wilderness Medical Society practice guidelines for the prevention and treatment of heat-related illness: 2014 update. Wilderness Environ Med 2015; 25:S55-65. [PMID: 25498263 DOI: 10.1016/j.wem.2014.07.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 06/26/2014] [Accepted: 07/01/2014] [Indexed: 11/29/2022]
Abstract
The Wilderness Medical Society (WMS) convened an expert panel to develop a set of evidence-based guidelines for the recognition, prevention, and treatment of heat illness. We present a review of the classifications, pathophysiology, and evidence-based guidelines for planning and preventive measures as well as best practice recommendations for both field and hospital-based therapeutic management of heat illness. These recommendations are graded on the basis of the quality of supporting evidence, and balance between the benefits and risks or burdens for each modality. This is an updated version of the original WMS Practice Guidelines for the Prevention and Treatment of Heat-Related Illness published in Wilderness & Environmental Medicine 2013;24(4):351-361.
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Affiliation(s)
- Grant S Lipman
- Division of Emergency Medicine, Stanford University School of Medicine, Stanford, CA (Dr Lipman).
| | - Kurt P Eifling
- Division of Emergency Medicine, Barnes-Jewish Hospital/Washington University School of Medicine, Saint Louis, MO (Dr Eifling)
| | - Mark A Ellis
- Department of Emergency Medicine, Spartanburg Regional Healthcare System, Spartanburg, SC (Dr Eifling)
| | - Flavio G Gaudio
- Division of Emergency Medicine, New York-Presbyterian Hospital/Weill Cornell Medical College, New York, NY (Dr Gaudio)
| | - Edward M Otten
- Department of Emergency Medicine, University of Cincinnati, Cincinnati, OH (Dr Otten)
| | - Colin K Grissom
- Pulmonary and Critical Care Division, Intermountain Medical Center and the University of Utah, Salt Lake City, UT (Dr Grissom)
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Oakes J. Alliances in Human Biology: The Harvard Committee on Industrial Physiology, 1929-1939. JOURNAL OF THE HISTORY OF BIOLOGY 2015; 48:365-390. [PMID: 26024783 DOI: 10.1007/s10739-014-9396-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In 1929 the newly-reorganized Rockefeller Foundation funded the work of a cross-disciplinary group at Harvard University called the Committee on Industrial Physiology (CIP). The committee's research and pedagogical work was oriented towards different things for different members of the alliance. The CIP program included a research component in the Harvard Fatigue Laboratory and Elton May's interpretation of the Hawthorne Studies; a pedagogical aspect as part of Wallace Donham's curriculum for Harvard Business School; and Lawrence Henderson's work with the Harvard Pareto Circle, his course Sociology 23, and the Harvard Society of Fellows. The key actors within the CIP alliance shared a concern with training men for elite careers in government service, business leadership, and academic prominence. But the first communications between the CIP and the Rockefeller Foundation did not emphasize training in human biology. Instead, the CIP presented itself as a coordinating body that would be able to organize all the varied work going on at Harvard that did not fit easily into one department, and it was on this basis that the CIP became legible to the President of Harvard, A. Lawrence Lowell, and to Rockefeller's Division of Social Sciences. The members of the CIP alliance used the term human biology for this project of research, training and institutional coordination.
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Affiliation(s)
- Jason Oakes
- University of California, Davis, Davis, CA, USA,
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10
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Abstract
The objective of this article is to provide a review of the fundamental aspects of body fluid balance and the physiological consequences of water imbalances, as well as discuss considerations for the optimal composition of a fluid replacement beverage across a broad range of applications. Early pioneering research involving fluid replacement in persons suffering from diarrheal disease and in military, occupational, and athlete populations incurring exercise- and/or heat-induced sweat losses has provided much of the insight regarding basic principles on beverage palatability, voluntary fluid intake, fluid absorption, and fluid retention. We review this work and also discuss more recent advances in the understanding of fluid replacement as it applies to various populations (military, athletes, occupational, men, women, children, and older adults) and situations (pathophysiological factors, spaceflight, bed rest, long plane flights, heat stress, altitude/cold exposure, and recreational exercise). We discuss how beverage carbohydrate and electrolytes impact fluid replacement. We also discuss nutrients and compounds that are often included in fluid-replacement beverages to augment physiological functions unrelated to hydration, such as the provision of energy. The optimal composition of a fluid-replacement beverage depends upon the source of the fluid loss, whether from sweat, urine, respiration, or diarrhea/vomiting. It is also apparent that the optimal fluid-replacement beverage is one that is customized according to specific physiological needs, environmental conditions, desired benefits, and individual characteristics and taste preferences.
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Baker LB, Ungaro CT, Barnes KA, Nuccio RP, Reimel AJ, Stofan JR. Validity and reliability of a field technique for sweat Na+ and K+ analysis during exercise in a hot-humid environment. Physiol Rep 2014; 2:e12007. [PMID: 24793982 PMCID: PMC4098735 DOI: 10.14814/phy2.12007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
This study compared a field versus reference laboratory technique for extracting (syringe vs. centrifuge) and analyzing sweat [Na+] and [K+] (compact Horiba B‐722 and B‐731, HORIBA vs. ion chromatography, HPLC) collected with regional absorbent patches during exercise in a hot‐humid environment. Sweat samples were collected from seven anatomical sites on 30 athletes during 1‐h cycling in a heat chamber (33°C, 67% rh). Ten minutes into exercise, skin was cleaned/dried and two sweat patches were applied per anatomical site. After removal, one patch per site was centrifuged and sweat was analyzed with HORIBA in the heat chamber (CENTRIFUGE HORIBA) versus HPLC (CENTRIFUGE HPLC). Sweat from the second patch per site was extracted using a 5‐mL syringe and analyzed with HORIBA in the heat chamber (SYRINGE HORIBA) versus HPLC (SYRINGE HPLC). CENTRIFUGE HORIBA, SYRINGE HPLC, and SYRINGE HORIBA were highly related to CENTRIFUGE HPLC ([Na+]: ICC = 0.96, 0.94, and 0.93, respectively; [K+]: ICC = 0.87, 0.92, and 0.84, respectively), while mean differences from CENTRIFUGE HPLC were small but usually significant ([Na+]: 4.7 ± 7.9 mEql/L, −2.5 ± 9.3 mEq/L, 4.0 ± 10.9 mEq/L (all P < 0.001), respectively; [K+]: 0.44 ± 0.52 mEq/L (P < 0.001), 0.01 ± 0.49 mEq/L (P = 0.77), 0.50 ± 0.48 mEq/L (P < 0.001), respectively). On the basis of typical error of the measurement results, sweat [Na+] and [K+] obtained with SYRINGE HORIBA falls within ±15.4 mEq/L and ±0.68 mEq/L, respectively, of CENTRIFUGE HPLC 95% of the time. The field (SYRINGE HORIBA) method of extracting and analyzing sweat from regional absorbent patches may be useful in obtaining sweat [Na+] when rapid estimates in a hot‐humid field setting are needed. This study compared a field versus reference laboratory technique for extracting (SYRINGE vs. CENTRIFUGE) and analyzing sweat [Na+] and [K+] (compact HORIBA B‐722 and B‐731 versus ion chromatography, HPLC) collected with regional absorbent patches during exercise in a hot‐humid environment. The HORIBA analyzers provided highly reliable test‐retest and day‐to‐day measurements of sweat [Na+] and [K+]. The 95% limit of agreement between the SYRINGE HORIBA field technique and the reference laboratory‐based CENTRIFUGE HPLC technique was ±15.4 mEq/L and ±0.68 mEq/L for [Na+] and [K+], respectively; which may be acceptable in a field‐testing context, when simply aiming to estimate electrolyte losses for the purpose of identifying athletes/workers at greater risk for large electrolyte losses.
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Affiliation(s)
- Lindsay B Baker
- Gatorade Sports Science Institute, Barrington, Illinois, USA
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Abstract
Dehydration, if sufficiently severe, impairs both physical and mental performance, and performance decrements are greater in hot environments and in long-lasting exercise. Athletes should begin exercise well hydrated and should drink during exercise to limit water and salt deficits. Many athletes are dehydrated to some degree when they begin exercise. During exercise, most drink less than their sweat losses, some drink too much and a few develop hyponatraemia. Athletes should learn to assess their hydration needs and develop a personalized hydration strategy that takes account of exercise, environment and individual needs. Pre-exercise hydration status can be assessed from urine frequency and volume, with additional information from urine color, specific gravity or osmolality. Changes in hydration status during exercise can be estimated from the change in body mass: sweat rate can be estimated if fluid intake and urinary losses are also measured. Sweat salt losses can be determined by collection and analysis of sweat samples. An appropriate, individualized drinking strategy will take account of pre-exercise hydration status and of fluid, electrolyte and substrate needs before, during and after a period of exercise.
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Affiliation(s)
- R J Maughan
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
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Stone MB, Edwards JE, Huxel KC, Cordova ML, Ingersoll CD, Babington JP. Threshold frequency of an electrically induced cramp increases following a repeated, localized fatiguing exercise. J Sports Sci 2010; 28:399-405. [PMID: 20131142 DOI: 10.1080/02640410903508854] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Though clinical observations and laboratory data provide some support for the neuromuscular imbalance theory of the genesis of exercise-associated muscle cramps, no direct evidence has been published. The purpose of this study was to determine the effect of local muscle fatigue on the threshold frequency of an electrically induced muscle cramp. To determine baseline threshold frequency, a cramp was electrically induced in the flexor hallucis brevis of 16 apparently healthy participants (7 males, 9 females; age 25.1 +/- 4.8 years). The testing order of control and fatigue conditions was counterbalanced. In the control condition, participants rested in a supine position for 30 min followed by another cramp induction to determine post-threshold frequency. In the fatigue condition, participants performed five bouts of great toe curls at 60% one-repetition maximum to failure with 1 min rest between bouts followed immediately by a post-threshold frequency measurement. Repeated-measures analysis of variance and simple main effects testing showed post-fatigue threshold frequency (32.9 +/- 11.7 Hz) was greater (P < 0.001) than pre-fatigue threshold frequency (20.0 +/- 7.7 Hz). An increase in threshold frequency seems to demonstrate a decrease in one's propensity to cramp following the fatigue exercise regimen used. These results contradict the proposed theory that suggests cramp propensity should increase following fatigue. However, differences in laboratory versus clinical fatiguing exercise and contributions from other sources, as well as the notion of a graded response to fatiguing exercise, on exercise-associated muscle cramp and electrically induced muscle cramp should be considered.
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Schwellnus MP, Drew N, Collins M. Muscle cramping in athletes--risk factors, clinical assessment, and management. Clin Sports Med 2008; 27:183-94, ix-x. [PMID: 18206574 DOI: 10.1016/j.csm.2007.09.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Exercise associated muscle cramping (EAMC) is defined as a painful, spasmodic, and involuntary contraction of skeletal muscle that occurs during or immediately after exercise. There is a high lifetime prevalence of EAMC in athletes, specifically in endurance athletes. The most important risk factors for EAMC in athletes are a previous history of EAMC, and performing exercise at a higher relative exercise intensity or duration, when compared with normal training and participating in hot and humid environmental conditions. The diagnosis of EAMC is made clinically, and the most effective immediate management of EAMC is rest and passive stretching. The key to the prevention of EAMC is to reduce the risk of developing premature muscle fatigue.
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Affiliation(s)
- Martin P Schwellnus
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, 3rd Floor, Sports Science Institute of South Africa, Boundary Road, Newlands, Cape Town 7700, South Africa.
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Abstract
Much has transpired in the world of sports medicine since Herodicus, a Thracian physician of the fifth century BC, rendered his foundational theories on the use of therapeutic exercise for the maintenance of health and the treatment of disease. Unfortunately, as basic knowledge advances, history abounds in inconsistencies in regard to the proper and most effective delivery of sports medicine. This article traces the development of sports medicine and its relation to high school, college, and Olympic sports over the last centuries, and provides glimpses into what the future of the field may hold.
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Gregory RA, Lee DH. The effect of water intake upon human reactions to reduced cooling powers. J Physiol 2007; 86:204-18. [PMID: 16994747 PMCID: PMC1394599 DOI: 10.1113/jphysiol.1936.sp003355] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Abstract
'Heat cramping' is defined here as severe, spreading, sustained, sharply painful muscle contractions that can sideline athletes. Not all cramps are alike, but three lines of evidence suggest heat cramping is caused by 'salty sweating', specifically by the triad of salt loss, fluid loss and muscle fatigue. The first line of evidence is historical. Dating back 100 years, heat cramping in industrial workers was alleviated by saline, and in a self-experiment, salt depletion provoked muscle cramping. The second line of evidence is from field studies of athletes. In tennis and football alike, heat-crampers tend to be salty sweaters. Some evidence also suggests that triathletes who cramp may lose more salt during the race than peers who do not cramp. The third line of evidence is practical experience with therapy and prevention. Intravenous saline can reverse heat cramping, and more salt in the diet and in sports drinks can help prevent heat cramping. For heat cramping, the solution is saline.
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Affiliation(s)
- E Randy Eichner
- Health Sciences Center, University of Oklahoma, Oklahoma City, Oklahoma 73111-6657, USA.
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18
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Abstract
Skeletal muscle cramps are commonly encountered in marathon runners by medical staff. However, the aetiology, and therefore management, of this condition is not well understood. Exercise-associated muscle cramping (EAMC) is defined as an involuntary, painful contraction of skeletal muscle during or immediately after exercise. In early anecdotal reports, cramps were associated with profuse sweating, together with changes in serum electrolyte concentrations. No mechanism explains how such imbalances in serum electrolytes result in localised muscle cramping. The 'muscle fatigue' hypothesis suggests that EAMC is the result of an abnormality of neuromuscular control at the spinal level in response to fatiguing exercise and is based on evidence from epidemiological studies, animal experimental data on spinal reflex activity during fatigue and electromyogram data recorded during bouts of acute cramping after fatiguing exercise. The development of premature muscle fatigue appears to explain the onset of EAMC.
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Affiliation(s)
- Martin P Schwellnus
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
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Ferris EB, Blankenhorn MA, Robinson HW, Cullen GE. HEAT STROKE: CLINICAL AND CHEMICAL OBSERVATIONS ON 44 CASES. J Clin Invest 2006; 17:249-62. [PMID: 16694569 PMCID: PMC424982 DOI: 10.1172/jci100949] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- E B Ferris
- Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati
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Ropes MW, Bennett GA, Bauer W. THE ORIGIN AND NATURE OF NORMAL SYNOVIAL FLUID. J Clin Invest 2006; 18:351-72. [PMID: 16694669 PMCID: PMC434882 DOI: 10.1172/jci101050] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- M W Ropes
- Medical Clinic of the Massachusetts General Hospital, Boston
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Landis EM, Elsom KA, Bott PA, Shiels E. OBSERVATIONS ON SODIUM CHLORIDE RESTRICTION AND UREA CLEARANCE IN RENAL INSUFFICIENCY. J Clin Invest 2006; 14:525-41. [PMID: 16694326 PMCID: PMC424707 DOI: 10.1172/jci100703] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- E M Landis
- Department of Medicine, University of Pennsylvania, Philadelphia
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Talbott JH, Jacobson BM, Oberg SA. THE ELECTROLYTE BALANCE IN ACUTE GOUT. J Clin Invest 2006; 14:411-21. [PMID: 16694315 PMCID: PMC424696 DOI: 10.1172/jci100692] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- J H Talbott
- Medical Clinic of the Massachusetts General Hospital, Boston
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Schwellnus MP, Derman EW, Noakes TD. Aetiology of skeletal muscle 'cramps' during exercise: a novel hypothesis. J Sports Sci 1997; 15:277-85. [PMID: 9232553 DOI: 10.1080/026404197367281] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The aetiology of exercise-associated muscle cramps (EAMC), defined as 'painful, spasmodic, involuntary contractions of skeletal muscle during or immediately after physical exercise', has not been well investigated and is therefore not well understood. This review focuses on the physiological basis for skeletal muscle relaxation, a historical perspective and analysis of the commonly postulated causes of EAMC, and known facts about EAMC from recent clinical studies. Historically, the causes of EAMC have been proposed as (1) inherited abnormalities of substrate metabolism ('metabolic theory') (2) abnormalities of fluid balance ('dehydration theory'), (3) abnormalities of serum electrolyte concentrations ('electrolyte theory') and (4) extreme environmental conditions of heat or cold ('environmental theory'). Detailed analyses of the available scientific literature including data from recent studies do not support these hypothesis for the causes of EAMC. In a recent study, electromyographic (EMG) data obtained from runners during EAMC revealed that baseline activity is increased (between spasms of cramping) and that a reduction in the baseline EMG activity correlates well with clinical recovery. Furthermore, during acute EAMC the EMG activity is high, and passive stretching is effective in reducing EMG activity. This relieves the cramp probably by invoking the inverse stretch reflex. In two animal studies, abnormal reflex activity of the muscle spindle (increased activity) and the Golgi tendon organ (decreased activity) has been observed in fatigued muscle. We hypothesize that EAMC is caused by sustained abnormal spinal reflex activity which appears to be secondary to muscle fatigue. Local muscle fatigue is therefore responsible for increased muscle spindle afferent and decreased Golgi tendon organ afferent activity. Muscles which cross two joints can more easily be placed in shortened positions during exercise and would therefore decrease the Golgi tendon organ afferent activity. In addition, sustained abnormal reflex activity would explain increased baseline EMG activity between acute bouts of cramping. Finally, passive stretching invokes afferent activity from the Golgi tendon organ, thereby relieving the cramp and decreasing EMG activity.
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Affiliation(s)
- M P Schwellnus
- MRC/UCT Bioenergetics of Exercise Research Unit, University of Cape Town Medical School, Newlands, South Africa
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Abstract
The hyponatremia of exercise may exist in symptomatic and asymptomatic forms. Symptomatic hyponatremia is usually characterized by severe alterations in cerebral function including coma and grand mal seizures; it develops especially in less competitive athletes who have maintained high rates of fluid intake during endurance events lasting at least 5 hours. The hyponatremia becomes symptomatic when the volume of excess fluid retained exceeds 2 to 3 liters. The etiology of the condition is unknown. Possibly as many as three or more pathologies (abnormal fluid retention possibly due to inappropriate ADH secretion, abnormal regulation of the extracellular fluid volume, translocation of sodium into a "third space") must be present for symptomatic hyponatremia to develop. The avoidance of overhydration would appear to be the only certain way that susceptible individuals can prevent symptomatic hyponatremia. Sodium chloride containing solutions ingested in physiologically significant concentrations would likely prevent a possible "third space" effect.
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Affiliation(s)
- T D Noakes
- Dept. of Physiology, University of Cape Town Medical School, Observatory, South Africa
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Arbeitsphysiologie. Rev Physiol Biochem Pharmacol 1939. [DOI: 10.1007/bf02322412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Glatzel H. Über das Kochsalzbedürfnis des Menschen. Clin Exp Med 1939. [DOI: 10.1007/bf02607582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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McLain PL, Montgomery ES. OBSERVATIONS ON THE BLOOD OF WORKMEN EXPOSED TO HIGH TEMPERATURES. J Clin Invest 1938; 17:417-22. [PMID: 16694588 PMCID: PMC434797 DOI: 10.1172/jci100968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- P L McLain
- Department of Physiology and Pharmacology, University of Pittsburgh, Pittsburgh
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Die Bedeutung des Flüssigkeits- und Chlorersatzes für die Leistungsfähigkeit des Hitzearbeiters. Eur J Appl Physiol 1937. [DOI: 10.1007/bf02009878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ein neues Syndrom zur Diagnostik von Balkentumoren. J Neurol 1935. [DOI: 10.1007/bf01761187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Derrick EH. HEAT CRAMPS AND URÆMIC CRAMPS, WITH SPECIAL REFERENCE TO THEIR TREATMENT WITH SODIUM CHLORIDE. Med J Aust 1934. [DOI: 10.5694/j.1326-5377.1934.tb91456.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Tierexperimentelle Untersuchungen zur Chlorverarmung des Organismus. Naunyn Schmiedebergs Arch Pharmacol 1933. [DOI: 10.1007/bf01860945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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