Some good information regarding safe running.
I. Tips for a Safe Running Program
Plan for Your Environment
Although running injuries are quite common, you can reduce your risk for injury. Be sure to follow the proper conditioning and training programs, wear the appropriate apparel and footwear, and be aware of your running environment.
Plan for Your Environment
- Run in the shade, if possible, to avoid direct sun. If exposed to the sun, apply at least SPF 15 sunscreen. Wear sunglasses to filter out UVA and UVB rays, and wear a hat with a visor to shade your eyes and face.
- During hot weather, run in the early morning or evening to avoid heat exhaustion. Do not run when pollution levels are high.
- In high altitudes, gradually acclimate yourself to lower oxygen levels by slowly increasing your speed and distance.
- In cool weather, you are less likely to get chilled if you run into the wind when you start running and run with the wind at the finish.
- Do not run at night. If you run at dusk or dawn, wear reflective material. Do not wear a headset or jewelry while running.
- Whenever possible, run on a clear, smooth, resilient, even, and reasonably soft surface. Avoid running on hills, which increases stress on the ankle and foot. When running on a curve, such as a running track, reverse directions halfway through your run so that you have even pressure on both feet during the run.
- Plan a progressive running program to prevent injuries. A five-minute warm-up (which should raise your temperature by one degree) followed by stretching exercises, is essential before starting a run. Following the run, stretching again is important.
- Start your run with your body feeling “a little cool.” Your body temperature will increase when you start running.
- Run with a partner. If alone, carry identification, or write your name, phone number, blood type, and medical information on the inside sole of your running shoe.
- Let others know where you will be running, and stay in familiar areas, away from traffic. If possible, carry a small bag for a cell phone and a whistle or other noisemaker to use in an emergency.
- When selecting a running shoe, look for good shock absorption and construction that will provide stability and cushioning to the foot. Make sure that there is a thumbnail’s width between the end of the longest toe and the end of the shoe. Buy shoes at the end of the day when your foot is the largest.
- Sixty percent of a shoe’s shock absorption is lost after 250 to 500 miles of use, so people who run up to 10 miles per week should consider replacing their shoes every 9 to 12 months.
- Excessive clothing can produce sweating, which causes the body to lose heat rapidly and can increase the risk of hypothermia. Instead, dress in layers. The inner layer should be material that takes perspiration away from the skin (polypropylene, thermal); the middle layer (not necessary for legs) should be for insulation and absorbing moisture (cotton); the outer layer should protect against wind and moisture (nylon).
- To avoid frostbite in cold weather, do not have gaps of bare skin between gloves and jackets, wear a hat, and cover your neck. Petroleum jelly can be used on exposed areas, such as the nose.
- You can lose between six and 12 ounces of fluid for every 20 minutes of running. Drink 10 to 15 ounces of fluid 10 to 15 minutes prior to running and every 20 to 30 minutes along your route. Weigh yourself before and after a run. For every pound lost, drink one pint of fluid.
II. How to Run Safely in the Heat and Humidity
Running in heat and humidity can put you at risk for dehydration, heat stroke and other heat-related illnesses. Common sense is the key to avoiding problems, so be sure to follow these precautions:
The easiest way to avoid heat disorders is to keep your body hydrated. This means drinking fluids before, during and after exercise. The body’s fluid needs vary with exertion, climate, humidity, terrain, and other factors. The new fluid recommendations for runners say that they should “obey your thirst” and drink when their mouth is dry and they feel the need to drink. In training, drink before workouts and make sure you have access to fluids if exercising longer than 30 minutes.
Choose Clothing Carefully
Light-colored, loose-fitting clothing will help your body breathe and cool itself down naturally. Tight clothing restricts that process and dark colors absorb the sun’s light and heat. Wear synthetic fabrics (not cotton) because they will wick moisture away from your skin so cooling evaporation can occur.
Run Early or Late
Try to avoid running between 10 a.m. and 4 p.m., when the sun’s intensity is at its greatest. If you must train during those hours, try to stick to shady roads or trails. Morning (before sunrise or right after) is the coolest time of the day to run since the roads have not heated up during the day.
Protect your skin with a waterproof sunscreen that has an SPF of at least 15 and offers broad-spectrum protection, which means it protects against both UVA and UVB rays. Stick formulations are good for runners’ faces because the sunscreen won’t run into your eyes.
Don’t Push It
On a race day (or during any intense workout), take weather conditions into account. Brutal heat and humidity mean you should scale back your performance goals. Don’t try to beat the heat. Hot and humid conditions are not the time to try to push your pace. Slow down, take walking breaks, and save your hard efforts for cooler weather.
Make a Splash
Use water to cool yourself during runs. If you are overheating, splashing water on your head and body will cool you down quickly and have a lasting effect as the water evaporates from your skin.
You should be very familiar with the signs of heat problems so you recognize them in yourself or in a running partner. If you feel faint, dizzy, disoriented, have stopped sweating, or your skin is cool and clammy, slow down or stop running. If symptoms continue, sit or lie down in the shade and seek help.
III. Heat Cramps Symptoms, Causes, Prevention, and Treatment
What It Is and Symptoms:
Heat cramps are painful, involuntary muscle spasms that usually occur during intense exercise in a hot climate. Symptoms include muscle cramps and/or spasms, heavy sweating, normal body temperature. Heat cramps may happen in any muscle group involved in exercise, but the most commonly affected muscles are calves, arms, abs, and back.
Severe cramping may occur when you have been sweating excessively and losing electrolytes.
The easiest way to avoid heat disorders is to keep your body hydrated by drinking fluids before, during, and after exercise. The body’s fluid needs vary with exertion, weather, terrain, and other factors. Fluid recommendations for runners say that they should “obey your thirst” and drink when their mouth is dry and they feel the need to drink. Drink before workouts and make sure you have access to fluids if exercising more than 30 minutes. During longer workouts, some of your fluids should include a sports drink to replace lost salt and electrolytes.
If you’re suffering from heat cramps, stop running immediately and drink fluids (especially a sports drink to replace electrolytes). Get in the shade and try cooling your body with cold water and wet towels. Gently massage the affected area. Contact your doctor if your cramps don’t go away within an hour.
IV. Heat Exhaustion Symptoms, Causes, Prevention, and Treatment
Symptoms of heat exhaustion include fatigue; goose bumps; weakness; headaches dizziness; nausea; vomiting; decreased coordination; possible fainting; and skin that is cool, moist, pale, or flushed.
Heat exhaustion occurs when you cannot sweat enough to cool your body. It most commonly happens when exercising intensely in a hot, humid condition.
The easiest way to avoid heat disorders is to drink fluids before, during and after exercise. The body’s fluid needs vary with exertion, climate, humidity, terrain, and other factors. The new fluid recommendations say that runners should “obey your thirst” and drink when their mouth is dry and they feel the need to drink. Drink before workouts and make sure you have access to fluids if exercising longer than 30 minutes. During longer workouts, some of your fluid intake should include a sports drink to replace lost salt and other minerals (electrolytes).
It’s also important that runners take weather conditions into account when determining how fast or far they’re running. Brutal heat and humidity mean you should scale back your performance goals. Don’t try to beat the heat. Hot and humid conditions are not the time to try to push your pace. Slow down, take walking breaks, and save your hard efforts for cooler weather. Stick to the treadmill if you want to run usual pace and distance.
If you experience symptoms of heat exhaustion, stop running immediately. Drink fluids and get in the shade or an air-conditioned room as soon as possible. Loosen or remove excess clothing.
“Exercise and Fluid Replacement”, ACSM Position Stand, American College Of Sports Medicine, Medicine and Science In Sports & Exercise, 2007.
Tamara Hew-Butler, DPM, Joseph G. Verbalis, MD, and Timothy D. Noakes, MBChB, MD, DSc, “Updated Fluid Recommendation: Position Statement From the International Marathon Medical Directors Association (IMMDA),” Clinical Journal of Sports Medicine, 2006;16:283–292)
V. Heat stroke
Heatstroke is defined typically as hyperthermia exceeding 41°C and anhidrosis associated with an altered sensorium. However, when a patient is allowed to cool down prior to measurement of the temperature (as may occur during transportation in a cool ambulance or evaluation in an emergency department), the measured temperature may be much lower than 41°C, making the temperature criterion relative. Similarly, some patients may retain the ability to sweat, removing anhidrosis as a criterion for the diagnosis of heatstroke. Therefore, strict adherence to the definition is not advised because it may result in dangerous delays in diagnosis and therapy.
Clinically, 2 forms of heatstroke are differentiated. Classic heatstroke, which occurs during environmental heat waves, is more common in very young persons and in the elderly population and should be suspected in children, elderly persons, and individuals who are chronically ill who present with an altered sensorium. Classic heatstroke occurs because of failure of the body’s heat dissipating mechanisms.
On the other hand, EHS affects young, healthy individuals who engage in strenuous physical activity, and EHS should be suspected in all individuals with bizarre irrational behavior or a history of syncope during strenuous exercise. EHS results from increased heat production, which overwhelms the body’s ability to dissipate heat.
EHS is characterized by hyperthermia, diaphoresis, and an altered sensorium, which may manifest suddenly during extreme physical exertion in a hot environment.
A number of symptoms (eg, abdominal and muscular cramping, nausea, vomiting, diarrhea, headache, dizziness, dyspnea, weakness) commonly precede the heatstroke and may remain unrecognized. Syncope and loss of consciousness also are observed commonly before the development of EHS.
EHS commonly is observed in young, healthy individuals (eg, athletes, firefighters, military personnel) who, while engaging in strenuous physical activity, overwhelm their thermoregulatory system and become hyperthermic. Because their ability to sweat remains intact, patients with EHS are able to cool down after cessation of physical activity and may present for medical attention with temperatures well below 41°C. Despite education and preventative measures, EHS is still the third most common cause of death among high school students.
Risk factors that increase the likelihood of heat-related illnesses include a preceding viral infection, dehydration, fatigue, obesity, lack of sleep, poor physical fitness, and lack of acclimatization. Although lack of acclimatization is a risk factor for heatstroke, EHS also can occur in acclimatized individuals who are subjected to moderately intense exercise.
Patients commonly exhibit evidence of hepatic injury, including jaundice and elevated liver enzymes.
Rarely, fulminant hepatic failure occurs, accompanied by encephalopathy, hypoglycemia, and disseminated intravascular coagulation (DIC) and bleeding.
Muscle tenderness and cramping are common; rhabdomyolysis is a common complication of EHS.
The patient’s muscles may be rigid or limp.
Acute renal failure (ARF) is a common complication of heatstroke and may be due to hypovolemia, low cardiac output, and myoglobinuria (due to rhabdomyolysis).
Patients may exhibit oliguria and a change in the color of urine.
Central nervous system
Symptoms of CNS dysfunction are present universally in persons with heatstroke. Symptoms may range from irritability to coma.
Patients may present with delirium, confusion, delusions, convulsions, hallucinations, ataxia, tremors, dysarthria, and other cerebellar findings, as well as cranial nerve abnormalities and tonic and dystonic contractions of the muscles.
Patients also may exhibit decerebrate posturing, decorticate posturing, or they may be limp.
Coma also may be caused by electrolyte abnormalities, hypoglycemia, hepatic encephalopathy, uremic encephalopathy, and acute structural abnormalities, such as intracerebral hemorrhage due to trauma or coagulation disorders.
Cerebral edema and herniation also may occur during the course of heatstroke.
Arterial blood gas analysis: ABG analysis may reveal respiratory alkalosis due to direct CNS stimulation and metabolic acidosis due to lactic acidosis. Hypoxia may be due to pulmonary atelectasis, aspiration pneumonitis, or pulmonary edema.
Lactic acidosis: Lactic acidosis commonly occurs following EHS but may signal a poor prognosis in patients with classic heatstroke.
Glucose: Hypoglycemia may occur in patients with EHS and in patients with fulminant hepatic failure.
Nutritional status and electrolytes
• Sodium: Hypernatremia due to reduced fluid intake and dehydration commonly is observed early in the course of disease but may be due to diabetes insipidus. Hyponatremia is observed in patients using hypotonic solutions, such as free water, and in patients using diuretics. It also may be due to excessive sweat sodium losses.
• Other: Hypophosphatemia secondary to phosphaturia and hyperphosphatemia secondary to rhabdomyolysis, hypocalcemia secondary to increased calcium binding in damaged muscle, and hypomagnesemia also are observed commonly.
Hepatic function tests
• Hepatic injury is a consistent finding in patients with heatstroke.
• Aminotransferases (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) commonly rise to the tens of thousands during the early phases of heatstroke and peak at 48 hours, but they may take as long as 2 weeks to peak.
• Jaundice may be striking and may be noted 36-72 hours after the onset of liver failure.
Muscle function tests
• Creatinine kinase (CK), lactate dehydrogenase (LDH), aldolase, and myoglobin commonly are released from muscles when muscle necrosis occurs.
• CK levels exceeding 100,000 IU/mL are common in patients with EHS.
• Elevations in myoglobin may not be noted despite muscle necrosis because myoglobin is metabolized rapidly by the liver and excreted rapidly by the kidneys.
Complete blood cell count: Elevated white blood cell counts commonly are observed in patients with heatstroke, and levels as high as 40,000 have been reported. Platelet levels may be low.
Renal function tests: Elevations in serum uric acid levels, blood urea nitrogen, and serum creatinine are common in patients whose course is complicated by renal failure.
Urinalysis: Remember that urinary benzidine dipsticks do not differentiate between blood, hemoglobin, and myoglobin. Urine dipstick analyses that are positive for blood must be followed by a microscopic urinalysis to determine the presence or absence of red blood cells. Proteinuria also is common.
Cerebrospinal fluid analysis: Cerebrospinal fluid (CSF) cell counts may show a nonspecific pleocytosis, and CSF protein levels may be elevated as high as 150 mg/dL.
Myoglobin causes a reddish brown discoloration of the urine but does not affect the color of plasma. This is in contrast to hemoglobin, which causes discoloration of both plasma and urine.
Heatstroke is a medical emergency. Rapid reduction of the core body temperature is the cornerstone of treatment because the duration of hyperthermia is the primary determinant of outcome. Except for the mildest cases, patients diagnosed with EHS or NEHS should be admitted to the hospital for at least 48 hours to monitor for complications.
Once heatstroke is suspected, cooling must begin immediately and must be continued during the patient’s resuscitation. According to the American College of Sports Medicine, the current recommendation is to initiate cooling immediately before transferring these patients to an emergency department for further evaluation and treatment. Controversy still exists over what therapeutic modality is most effective in the treatment of heatstroke; however, the basic premise of rapidly lowering the core temperature to about 39°C (avoid overshooting and rebound hyperthermia) remains the primary goal.
Some recent studies have shown that promptly reducing the exposure time to excessive heat can dramatically improve long-term outcomes and decrease irreversible injury. If treatment is initiated within this so-called golden hour and is aggressive enough to rapidly reduce the core body temperature, complications (including multisystem organ failure) may be averted and have a positive effect on the overall outcome of the patient.
Recently, a review of 19 past clinical trials and observational studies (involving 556 patients) was performed, and the conduction method of cooling was found to be more efficacious in young, active adults with EHS. Unfortunately from this review, there was no preferred treatment found for classical or NEHS and no temperature endpoint to prevent overcooling. However, to date, no controlled studies have compared the efficacy of the various cooling methods on time or outcome.
Removal of restrictive clothing and spraying water on the body, covering the patient with ice water–soaked sheets, or placing ice packs in the axillae and groin may reduce the patient’s temperature significantly. Patients who are unable to protect their airway should be intubated. Patients who are awake and responsive should receive supplemental oxygen. Intravenous lines may be placed in anticipation of fluid resuscitation and for the infusion of dextrose and thiamine if indicated. Hypoglycemia is a common occurrence in patients with EHS and may be a manifestation of liver failure; therefore, infusion of dextrose 50% in water solution (D50W) should be considered in all patients with heatstroke.
Intensive care personnel must pay meticulous attention to the airway, reduce the temperature, limit the production of heat, optimize circulation, and monitor for and treat complications.
• Insert a thermistor probe to monitor temperature continuously.
• Insert a nasogastric tube to monitor for gastrointestinal bleeding and fluid losses.
• Place a Foley catheter to monitor urine output.
The goal of treatment is to reduce the temperature by at least 0.2°C/min to approximately 39°C. Active external cooling generally is halted at 39°C to prevent overshooting, which can result in iatrogenic hypothermia.
• Place a flexible indwelling thermistor rectally or an esophageal probe to monitor core body temperature during treatment.
• Because thermal instability may persist for a few days after the onset of heatstroke, the temperature must be monitored continuously until it is stable.
The optimal method of rapidly cooling patients is a matter of debate; each method has its own theoretical advantages and disadvantages.
• Ice-water immersion or an equivalent method is an extremely effective method of rapidly reducing core body temperature and traditionally was the most frequently recommended method. The increased thermal conductivity of ice water can reduce core body temperature to less than 39°C in approximately 20-40 minutes. The practice has been criticized recently. Theoretically, the ice water, which may be extremely uncomfortable to patients who are awake, can cause subcutaneous vasoconstriction, preventing the transfer of heat via conduction. Ice water also increases shivering, which in turn increases internal heat production. Other reasons for the recent criticisms include difficulty monitoring and resuscitating patients.
• Recently, evaporative techniques have been touted to be as effective as immersion techniques without the practical difficulties. However, data on the efficacy of this method are limited. Evaporative body heat loss may be accomplished by removing all of the patient’s clothes and intermittently spraying the patient’s body with warm water while a powerful fan blows across the body, allowing the heat to evaporate.
• A number of other cooling techniques have been suggested, but none has proven superior to or equal to cold-water immersion or evaporative techniques. These include peritoneal, thoracic, rectal, and gastric lavage with ice water; cold intravenous fluids; cold humidified oxygen; cooling blankets; and wet towels.
• In the most severe cases, cardiopulmonary bypass has been suggested, but this requires highly trained personnel and sophisticated equipment.
• Antipyretics (eg, acetaminophen, aspirin, other nonsteroidal anti-inflammatory agents) have no role in the treatment of heatstroke because antipyretics interrupt the change in the hypothalamic set point caused by pyrogens. They are not expected to work on a healthy hypothalamus that has been overloaded, as in the case of heatstroke. In this situation, antipyretics actually may be harmful in patients who develop hepatic, hematologic, and renal complications because they may aggravate bleeding tendencies.
• Dantrolene has been studied as a possible pharmacological option in the treatment of hyperthermia and heatstroke, but at present, it has not been proven to be efficacious in clinical trials.
Along with immediate active cooling, steps to stop excessive production of heat must be taken.
Agitation and shivering should be treated immediately with benzodiazepines.
Benzodiazepines are the sedatives of choice in patients with sympathomimetic-induced delirium as well as alcohol and sedative drug withdrawals.
Neuroleptics, such as chlorpromazine, which were the mainstays of therapy in the past, are best avoided because of their deleterious adverse effects, including lowering of the seizure threshold, interference with thermoregulation, anticholinergic properties, hypotension, hepatotoxicity, and other adverse effects.
Similarly, convulsions must be controlled.
Benzodiazepines and, if necessary, barbiturates are the recommended agents in this setting. Barbiturates may be used despite their theoretical impedance of sweat production.
Phenytoin is not effective in controlling convulsions in this situation.
Patients whose convulsions are refractory to benzodiazepines and barbiturates should be paralyzed and provided mechanical ventilation. Electroencephalographic monitoring is recommended in all such patients, and anticonvulsant medications should be adjusted accordingly.
Recommendations on the administration of intravenous fluids for circulatory support differ among patient populations and depend on the presence of hypovolemia, preexisting medical conditions, and preexisting cardiovascular disease.
• While patients with heatstroke invariably are volume depleted, cooling alone may improve hypotension and cardiac function by allowing blood to redistribute centrally.
• Aggressive fluid resuscitation generally is not recommended because it may lead to pulmonary edema.
• Cor pulmonale also is a common finding in patients with heatstroke.
When pulse rate, blood pressure, and urine output do not provide adequate hemodynamic information, fluid administration should be guided by more invasive hemodynamic parameters, such as central venous pressure (CVP), pulmonary capillary wedge pressure, systemic vascular resistance index (SVRI), and cardiac index (CI) measurements.
• Patients who exhibit a hyperdynamic state (ie, high CI, low SVRI) generally respond to cooling and do not require large amounts of intravenous crystalloid infusions.
• Hypotensive patients who exhibit a hypodynamic response (ie, high CVP, low CI) traditionally have been treated with low-dose isoproterenol; however, its arrhythmogenicity has raised questions about its continued use. Dobutamine, which is less arrhythmogenic than isoproterenol and more cardioselective, may be the inotrope of choice in these patients.
• Alpha-adrenergic drugs generally are contraindicated because they cause vasoconstriction and may interfere with heat loss.
The occurrence of rhabdomyolysis may be heralded by the development of dark, tea-colored urine and tender edematous muscles.
• Rhabdomyolysis releases large amounts of myoglobin, which can precipitate in the kidneys and result in ARF. Renal failure especially is common in patients who develop hypotension or shock during the course of their disease and may occur in as many as 25-30% of patients with EHS.
• Treatment of rhabdomyolysis involves infusion of large amounts of intravenous fluids (fluid requirements may be as high as 10 L), alkalinization of the urine, and infusion of mannitol.
• Fluid administration is guided best by invasive hemodynamic parameters, and urine output should be maintained at 3 cc/kg/h to minimize the risk of renal failure.
• Alkalinization of the urine (urine pH 7.5-8.0) prevents the precipitation of myoglobin in the renal tubules and may control acidosis and hyperkalemia in acute massive muscle necrosis.
• Mannitol may improve renal blood flow and glomerular filtration rate, increase urine output, and prevent fluid accumulation in the interstitial compartment (through its osmotic action). Mannitol also is a free radical scavenger and, therefore, may reduce damage caused by free radicals.
• Once renal failure occurs, dialysis is the only effective therapeutic modality for rhabdomyolysis.
• Muscle necrosis may be so rapid that hyperkalemia, hypocalcemia, and hyperphosphatemia become significant enough to cause cardiac arrhythmias and require immediate therapy.
• In the presence of renal failure, hemodialysis may be necessary.
• Hypertonic dextrose and sodium bicarbonate may be used to shift potassium into the intracellular environment while more definitive measures (eg, intestinal potassium binding, dialysis) are prepared.
• Various other electrolyte abnormalities have been reported in patients with heatstroke and must be monitored closely and treated carefully. These abnormalities may be related to solute-altering conditions such as vomiting, diarrhea, and use of diuretics. For example, hypokalemia, which is common in the early phases of heatstroke, may develop in response to respiratory alkalosis, diarrhea, and sweating. Similarly, hyponatremia may be due to sodium losses and/or rehydration with salt-poor solutions (eg, water), and hypernatremia may be due to dehydration.
Heatstroke commonly leads to severe but reversible hepatic damage.
• Hepatic injury is represented by elevations in transaminase levels and bilirubin. During this phase, hypoglycemia, abnormal coagulation, cerebral edema, and death can occur, although rarely.
• Prolonged coagulation times also may signal the development of DIC, which, when present, carries a poor patient prognosis. Clinical manifestations can range from abnormal laboratory values to generalized bleeding occurring approximately 48 hours after the initial insult. DIC also may predispose patients to development of acute respiratory distress syndrome (ARDS), which also increases mortality.
• Treatment of hepatic failure includes the infusion of dextrose solutions to correct hypoglycemia; the early recognition and treatment of DIC, with replacement of clotting factors, fresh frozen plasma, platelets, and blood; and meticulous respiratory support.
Pulmonary edema is a common complication of heatstroke and may be due to a number of factors, including fluid overload from aggressive rehydration, fluid overload from renal failure, congestive heart failure, and ARDS. The latter may develop because of multiple insults, including heat-induced pulmonary damage, aspiration pneumonia, and as a complication of liver failure. ARDS should be treated aggressively, with early mechanical ventilation and positive end-expiratory pressure (PEEP).
ARF may occur because of direct thermal injury of the kidney, myoglobinuria, hypotension, and/or shock (acute tubular necrosis). Early manifestations of renal failure include oliguria, low-grade proteinuria, and granular casts.
• ARF initially is treated with intravenous fluids, diuretics, and correction of associated acid-base and electrolyte abnormalities.
• In the setting of rhabdomyolysis, mannitol may be the diuretic of choice because it does not interfere with the acid-base status of the urine, and it may have antioxidant activity.