424 Heat 2024 with Cases PDF

EXERCISE in HEAT AND COLD Michael Koehle MD PhD Professor Sports Medicine and Kinesiology University of British Columbia Objectives explain different modes of heat loss during exercise describe the key elements of diagnosing thermal illness and injury Heat Stroke/Heat Exhaustion Hyponatremia Hypothe...

EXERCISE in HEAT AND COLD Michael Koehle MD PhD Professor Sports Medicine and Kinesiology University of British Columbia Objectives explain different modes of heat loss during exercise describe the key elements of diagnosing thermal illness and injury Heat Stroke/Heat Exhaustion Hyponatremia Hypothermia Frostbite on field management of each of these conditions Understand Acclimatization to both How does this work? Is it worth $US350? HEAT LOSS DURING EXERCISE Evaporation Sweat evaporation Radiation Transmission of heat energy from a surface Conduction Transfer of heat from one substance to an adjacent substance Convection Transmission of heat to fluid which move away from the heat source Evaporation evaporation of water from the liquid phase to the gas phase requires heat cooling effect humidity plays a role HUMIDEX high humidity interferes with evaporation garments can play a role “3D mesh creates better sweat evaporation and promotes cooling.” Radiation Transmission of heat energy from a surface Think space blankets “Proprietory reflective fabric reflects sunlight and radiant heat up to 50% more than dark-coloured garments. It also shields UV rays with SPF50. ” Conduction transfer of thermal energy from one region to another along a temperature gradient “3D mesh created better sweat evaporation and promotes cooling.” “COTTON KILLS?” Convection If the fluid is going to move anyway: Forced convection Blood flow If the heat causes the motion of the fluid Free convection Flow of air around body “Hidden Hydro/aerodynamic pocket for increased performance. ” BEX Reviews I have been running with the Bex all summer and it has truly made a major difference in how I am able to beat the heat. The days I use the Bex, I run just a little longer and harder. A great inexpensive aid; as long as the device is cooler than the outside air, it helps transfer heat from the body. This is a training device that has to be used repeatedly in order to really gauge its benefits. Stick with it and you will see improvements in your stamina too! The description states that it "stays cool for 40 minutes" -it does not. You can still feel a sliver of ice in the center (if you push and squeeze on it) after 40 minutes - but it's not enough to reach the exterior of the product to cool your palm after about 25 minutes. It's great in the beginning - but quickly wears off. After it wears off, it becomes a nuisance on your hand rather than a help. I was ready to pitch it once the cool factor quit. I would not spend this much money on this product again, to only have the results last 20-25 minutes. It also claims to delay fatigue - I did not feel any different compared to running without this product. In fact, I normally run 3 miles - but stopped at 2.5 today instead of finishing. I Important... Sort of… “First company to design a race suit with vortex technology. Vortex generators reduce drag in water by 6%. ” Claims in detail How does this suit affect evaporation, radiation, convection, conduction? First thermoregulatory race suit to reduce heartrate up to 20% Proprietory reflective fabric reflects sunlight and radiant heat up to 50% more than dark-coloured garments. It also shields UV rays with SPF50. 3D mesh created better sweat evaporation and promotes cooling. First company to design a race suit with vortex technology. Vortex generators reduce drag in water by 6%. RSS Chamois Closed Cell Technology at only 2mm of thickness dampens road vibration up to 80% better than traditional chamois pad, it also stretched with your body - promoting comfort and eliminating chafing. Dimpled SCS coated leg panels for improved aero/hydrodynamics. Sophisticated RSS 360 Compression Technology utilizing ultralight 140 gram fabric, with equivalent compression of 220 gram with the same amount of stretch in all directions for reduced muscle fatigue. Hidden Hydro/aerodynamic pocket for increased performance. YKK Autolock designed zippers stay in place when locked. How does this work? Is it worth $US350? COLD Risk factors for Cold Injury Weather: wind chill, precipitation etc. Exhaustion, dehydration Clothing considerations Spinal Cord Injury impaired vasoconstriction, sensation Trauma Prolonged exposure Direct effect on hypothalamus affecting thermoregulation Hypothermia Decrease in body (core) temperature as a result of a cold environment. Hypothermia is a medical emergency. Mild (33-35°C) Moderate (31-32°C) Severe (65 Medications that: Alcohol, dehydration reduce sweating Overweight alter skin blood flow poor fitness/sedentary increase heat production Poor acclimatization reduce cardiac contractility Recent fever Sunburn or other skin conditions Exertional Heat Stroke Mental status changes and Tc > 40°C Complications include seizure, hypotension, rhabdomyolysis, liver damage, arrhythmias, disseminated intravascular coagulation Exertional Heat Stroke can occur in a variety of weather conditions metabolic heat production contributes to hyperthermia As opposed to classic heat stroke Prevention of Fatalities Recognition, recognition, recognition ABCs, core temperature (rectal) Ice to axilla, groin, neck if possible immerse in 1.67°-14.5°C water constant stirring Early Emergency Medical Services activation if onsite ice bath immersion not available intravenous access Heat Stroke Causes of Death Inaccurate Temperature measurement/misdiagnosis need a true core temperature Delayed Treatment patients left at the side of the field Inefficient Cooling must reduce temperature to < 40 degrees within 30 min if bath unavailable use 12 iced towels in 6:6 rotation Rapid return to play determine and mitigate cause full recovery necessary deacclimatisation/deconditioning during recovery Exertional Heat Stroke Return to Play Guidelines ACSM Refrain from exercise for at least 7 d after release from medical care; Follow up about 1 wk after incident for a physical examination and laboratory testing or diagnostic imaging of the affected organs, based on the clinical course of the heat stroke (HS) incident; When cleared for return to activity, begin exercise in a cool environment and gradually increase the duration, intensity, and heat exposure during 2 wk to demonstrate heat tolerance and to initiate acclimatization; If return to vigorous activity is not accomplished during 4 wk, a laboratory exercise-heat tolerance test should be considered; If heat tolerant, the athlete is cleared for full competition between 2 and 4 wk after the return to full training. Definition of Exercise Associated Hyponatremia (EAH) EAH is the occurrence of hyponatremia -during or up to 24 hours after prolonged physical activity and is defined by a serum or plasma sodium concentration ([Na+]) below the normal reference range of the laboratory performing the test. For most laboratories, this is a [Na+] less than 135 mmol/L. Exercise Associated Hyponatremia (EAH) Early signs and symptoms: bloating, “puffiness”, nausea, vomiting, and headache serious signs and symptoms: alteration of mental status (eg, confusion, disorientation, agitation, delirium), obtundation, coma seizures respiratory distress (pulmonary edema) serum [Na+]