Medical Complaints After a Marathon Run in Cool Weather

A new causative heat supply for exertional heat stroke on runners in cold air

The dysregulation in heat balance, the main cause of exertional heat stroke, occurs not only in midsummer but also in the cold season. Possible causes of this are a reduction in convection and evaporation due to tailwinds and an acceleration of radiant heat inflow. Although the amount of radiant heat that reaches the surface can be estimated, the actual amount of heat that flows into the body cannot be specified yet. This paper made an experimental attempt at this. A device is made up of a temperature controllable heat sink and heat flow detector, which keeps the surface temperature constant and has a heat exchange coefficient comparable to that of the human body surface. The output of this device (total heat exchange) was divided into radiant heat exchange and other heat exchange using a standard radiant heat calibrator, Leslie cube. A phenomenon, in which a wet surface while the surface temperature was low absorbed larger heat than that of the dry surface, was found. And authors named this "hidden heat inflow". As a result of multiple regression analyses, both radiant heat exchange and other heat exchanges are closely related to the surface temperature, and the maximum difference in total heat exchange during the experiment reached 200 kcal/m²/h. It has been suggested that this phenomenon may also occur on the surface of human skin. One of the causes of this "hidden heat inflow" is considered to be the decrease in evaporative cooling due to the decrease in surface temperature. However, this alone cannot explain all of the phenomena, so water vapor aggregation may also be involved. A "hidden heat inflow" as a sufficient heat source for exertional heat stroke or collapse during a marathon race on a cold day was evidenced experimentally.

Exercise-Associated Muscle Cramps in the Tennis Player

PURPOSE OF REVIEW

Better define the proposed etiologies, risk factors, and treatment plans for exercise-associated muscle cramps in the tennis player.

RECENT FINDINGS

While no one theory has been able to fully explain the etiology behind exercise-associated muscle cramping, further classification of acute localized cramping and systemic or recurrent cramping may help guide future treatment and prevention strategies. Neuromuscular fatigue more than electrolyte deficit or dehydration is believed to play a large role in development of exercise-associated muscle cramps. Despite inconclusive evidence at this time, electrolyte deficit may play more of a role in the development of recurrent or systemic muscle cramping in the tennis athlete. More research is needed to better define its conclusive etiology.

Muscular cramp: causes and management

Muscular cramp is a common symptom in healthy people, especially among the elderly and in young people after vigorous or peak exercise. It is prominent in a number of benign neurological syndromes. It is a particular feature of chronic neurogenic disorders, especially amyotrophic lateral sclerosis. A literature review was undertaken to understand the diverse clinical associations of cramp and its neurophysiological basis, taking into account recent developments in membrane physiology and modulation of motor neuronal excitability. Many aspects of cramping remain incompletely understood and require further study. Current treatment options are correspondingly limited.

Exercise-associated muscle cramps: causes, treatment, and prevention

CONTEXT

Exercise-associated muscle cramps (EAMC) are a common condition experienced by recreational and competitive athletes. Despite their commonality and prevalence, their cause remains unknown. Theories for the cause of EAMC are primarily based on anecdotal and observational studies rather than sound experimental evidence. Without a clear cause, treatments and prevention strategies for EAMC are often unsuccessful.

EVIDENCE ACQUISITION

A search of Medline (EBSCO), SPORTDiscus, and Silverplatter (CINHAL) was undertaken for journal articles written in English between the years 1955 and 2008. Additional references were collected by a careful analysis of the citations of others' research and textbooks.

RESULTS

Dehydration/electrolyte and neuromuscular causes are the most widely discussed theories for the cause of EAMC; however, strong experimental evidence for either theory is lacking.

CONCLUSIONS

EAMC are likely due to several factors coalescing to cause EAMC. The variety of treatments and prevention strategies for EAMC are evidence of the uncertainty in their cause. Acute EAMC treatment should focus on moderate static stretching of the affected muscle followed by a proper medical history to determine any predisposing conditions that may have triggered the onset of EAMC. Based on physical findings, prevention programs should be implemented to include fluid and electrolyte balance strategies and/or neuromuscular training.

National Athletic Trainers' Association position statement: environmental cold injuries

OBJECTIVE

To present recommendations for the prevention, recognition, and treatment of environmental cold injuries.

BACKGROUND

Individuals engaged in sport-related or work-related physical activity in cold, wet, or windy conditions are at risk for environmental cold injuries. An understanding of the physiology and pathophysiology, risk management, recognition, and immediate care of environmental cold injuries is an essential skill for certified athletic trainers and other health care providers working with individuals at risk.

RECOMMENDATIONS

These recommendations are intended to provide certified athletic trainers and others participating in athletic health care with the specific knowledge and problem-solving skills needed to address environmental cold injuries. Each recommendation has been graded (A, B, or C) according to the Strength of Recommendation Taxonomy criterion scale.

American College of Sports Medicine position stand: prevention of cold injuries during exercise

It is the position of the American College of Sports Medicine that exercise can be performed safely in most cold-weather environments without incurring cold-weather injuries. The key to prevention is use of a comprehensive risk management strategy that: a) identifies/assesses the cold hazard; b) identifies/assesses contributing factors for cold-weather injuries; c) develops controls to mitigate cold stress/strain; d) implements controls into formal plans; and e) utilizes administrative oversight to ensure controls are enforced or modified. The American College of Sports Medicine recommends that: 1) coaches/athletes/medical personnel know the signs/symptoms and risk factors for hypothermia, frostbite, and non-freezing cold injuries, identify individuals susceptible to cold injuries, and have the latest up-to-date information about current and future weather conditions before conducting training sessions or competitions; 2) cold-weather clothing be chosen based on each individual's requirements and that standardized clothing ensembles not be mandated for entire groups; 3) the wind-chill temperature index be used to estimate the relative risk of frostbite and that heightened surveillance of exercisers be used at wind-chill temperatures below -27 degrees C (-18 degrees F); and 4) individuals with asthma and cardiovascular disease can exercise in cold environments, but should be monitored closely.

Thermoregulation and marathon running: biological and environmental influences

The extreme physical endurance demands and varied environmental settings of marathon footraces have provided a unique opportunity to study the limits of human thermoregulation for more than a century. High post-race rectal temperatures (Tre) are commonly and consistently documented in marathon runners, yet a clear divergence of thought surrounds the cause for this observation. A close examination of the literature reveals that this phenomenon is commonly attributed to either biological (dehydration, metabolic rate, gender) or environmental factors. Marathon climatic conditions vary as much as their course topography and can change considerably from year to year and even from start to finish in the same race. The fact that climate can significantly limit temperature regulation and performance is evident from the direct relationship between heat casualties and Wet Bulb Globe Temperature (WBGT), as well as the inverse relationship between record setting race performances and ambient temperatures. However, the usual range of compensable racing environments actually appears to play more of an indirect role in predicting Tre by acting to modulate heat loss and fluid balance. The importance of fluid balance in thermoregulation is well established. Dehydration-mediated perturbations in blood volume and blood flow can compromise exercise heat loss and increase thermal strain. Although progressive dehydration reduces heat dissipation and increases Tre during exercise, the loss of plasma volume contributing to this effect is not always observed for prolonged running and may therefore complicate the predictive influence of dehydration on Tre for marathon running. Metabolic heat production consequent to muscle contraction creates an internal heat load proportional to exercise intensity. The correlation between running speed and Tre, especially over the final stages of a marathon event, is often significant but fails to reliably explain more than a fraction of the variability in post-marathon Tre. Additionally, the submaximal exercise intensities observed throughout 42 km races suggest the need for other synergistic factors or circumstances in explaining this occurrence. There is a paucity of research on women marathon runners. Some biological determinants of exercise thermoregulation, including body mass, surface area-to-mass ratio, sweat rate, and menstrual cycle phase are gender-discrete variables with the potential to alter the exercise-thermoregulatory response to different environments, fluid intake, and exercise metabolism. However, these gender differences appear to be more quantitative than qualitative for most marathon road racing environments.

Skeletal muscle cramps during exercise

Cramps are painful, involuntary contractions of skeletal muscle that occur during or immediately after exercise and are common in endurance athletes. Although cramps can occur in many rare medical conditions, most athletes who have exercise-associated muscle cramping do not have congenital or acquired medical disorders. The cause of cramping is not well understood but may have to do with abnormal spinal control of motor neuron activity, particularly when a muscle contracts in a shortened position. Important risk factors include muscle fatigue and poor stretching habits. Treatment consists mainly of passive stretching, with supportive measures as needed. Special diagnostic studies and conditioning programs may be necessary for recurrent episodes.

Aetiology of skeletal muscle 'cramps' during exercise: a novel hypothesis

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.

[Is suture of the ruptured anterior cruciate ligament without augmentation sensible?]

The five- and ten-years review of 40 patients with primary suture of the anterior cruciate ligament without augmentation showed all patients to have a positive Lachman-Test. Five years postoperatively 14 patients had no complaints, after ten years, only two patients remained free of symptoms. Five years after suture nine patients were limited at work, while after ten years this number had risen to twelve. Ten years after the suture only eleven patients had the same sporting abilities as before the accident; only six patients retained their level of performance. Six patients needed a meniscus-operation between the first and second review (five and ten years postoperatively). Radiologically we found signs of gonarthrosis in 15% at five years and 30% at ten years. 75% of the patients with gonarthrosis had had partial meniscectomy. Our results confirm that instability caused by an insufficient anterior cruciate ligament leads to higher incidence of meniscal tears and osteoarthritis. A primary suture of the anterior cruciate ligament without augmentation almost always leads to functional instability. This surgical procedure therefore is not recommended.

High school football injuries: a prospective study and pitfalls of data collection

A 4 year prospective study (1982 to 1985) of high school varsity football injuries from the four Peoria high school football teams was undertaken. Two hundred fifty-one injuries were recorded among a player population of 598, resulting in an injury rate of 42.1% per 100 players. All of the players followed a prescribed preseason summer conditioning program that was endorsed by the Illinois High School Athletic Association. The injuries were recorded on an athletic injury profile and entered into a computer for data analysis and retrieval. The injury distribution by player position showed that halfbacks, tackles, linebackers, and guards had a higher risk of injury than other positions. The knee was the body part injured most frequently (20.3%). A matrix of injuries to halfbacks was set up to examine the relationship of body part injured to type of play, time of injury, and activity during injury. An anthropometric study using the Quetelet index did not reveal any correlation between injury and body size when the injured players were compared with the non-injured players. Experience since 1969 has taught us many of the errors and pitfalls involved in injury surveillance. Strict adherence to recording of data will ensure an accurate and useful injury surveillance program.

Factors Associated With Collapse During and After Ultramarathon Footraces: A Preliminary Study

In brief: In a preliminary study to evaluate possible causes of exhaustion, 48 runners who collapsed during or after an ultramarathon race were questioned about their training methods. The training profiles were compared with those of matched controls who had finished the same race without collapsing. Possible contributing factors found among the collapsed runners included inadequate training, failing to carbohydrate load, not eating a prerace breakfast, prerace illness, and hypothermia (during one race, which was run in cold, wet, windy conditions). The authors suggest that regardless of athletic ability or previous racing experience, runners may be prone to collapse during or after ultramarathon races if their prerace training and preparation are inadequate.

Prophylactic knee bracing in college football

We report on the number of knee injuries sustained by a major college football team during 2 full years when all players were required to wear laterally placed prophylactic knee braces during all practice sessions and all games. We found that the incidence rates of knee injuries were higher when the braces were worn compared to a similar period when the braces were not worn. There was also an increased number of ACL injuries during the brace period. Several indices characterizing the nature of the injuries were analyzed and were found not to be altered significantly when the prophylactic braces were used. These facts lead us to question the efficacy of prophylactic knee braces in preventing knee injuries in college football. The use of the braces was associated with increased episodes of muscle cramping in the triceps surae muscle group, required the constant attention of coaches and trainers to remind the players to wear the braces and to apply them correctly, and was costly. These findings indicate the need for other carefully controlled clinical and biomechanical studies of these devices before their routine use can be advocated.

Prophylactic knee bracing in college football

American football can be harmful to knees. In an attempt to reduce the number and severity of knee injuries, the intercollegiate football team at the University of Arizona (Pacific Ten Conference) has been using protective braces since 1981. Objective evaluation of the effectiveness of this program is the purpose of this study. All linemen, offensive and defensive, as well as linebackers and tight ends were considered to be the players at greatest risk and were required to use the braces. The brace used was the Anderson Knee Stabler. Each player at each practice session or game was counted as one exposure. During the 4 years of brace use, there were 28,191 exposures, while the control group numbered 29,293 exposures. The data were analyzed from the perspectives of days lost from practice or games, player's position, the type and severity of injury, and the rate of injury per 100 players per season. Players at risk showed no trend to change in injury rate. Of the players at risk, the type and severity of injury in nonbraced and in braced groups were similar. A significant finding in players at risk was a two-fold increase in knee ligament injury rate per 100 players when compared to rates for an entire team. The number of season-ending injuries remained unchanged. Practice time missed for third-degree medial ligament, and for medial meniscus injuries, was significantly lower in the braced group, but this was due to improved treatment techniques initiated in 1981. Seven NCAA rule changes, directed at reducing knee injuries, have been introduced since 1981.(ABSTRACT TRUNCATED AT 250 WORDS)