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Heat Stress from the Sidelines

Heat Stress from the Sidelines. Dan Foster, PhD, ATC August 20, 2009. Case #1. 20 yo Div-I FB 6’3” / 274 lbs (BMI 33.5, VO 2 40.1) HIIS = high Day 15, On field WBGT 91 o F T c = 103.6 o F Nausea and dizziness after 1.5 hr. Emerson C, et al. Unpublished FIU. 2006.

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Heat Stress from the Sidelines

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  1. Heat Stress from the Sidelines Dan Foster, PhD, ATC August 20, 2009

  2. Case #1 • 20 yo Div-I FB • 6’3” / 274 lbs (BMI 33.5, VO2 40.1) • HIIS = high • Day 15, On field WBGT 91oF • Tc = 103.6oF • Nausea and dizziness after 1.5 hr Emerson C, et al. Unpublished FIU. 2006.

  3. Rested in shade - 101.7oF • Returned to drills and conditioning • Progressive dizziness, nausea, disorientation, pallor, transient LOC, sensation of heat – 102.7oF • Ice bags at neck and axilla – 102.7oF 10 min later could walk • Cool water bath (72oF) • In 14 min temp at 100.4oF

  4. BMI kg/m2 • Normal • 18.5-25 • Overweight • 25-30 • Obese • >30 > Heat production < Heat dissipation low specific heat Gardner J, et al. MSSE 1996; 28:939-944

  5. VO2 ml/kg/min • Acclimation to heat 10-14 days • Poor CV fitness 3 fold increase in risk Davies H. Cross training; 2009 Gardner J, et al. MSSE 1996; 28:939-944

  6. WBGT WBGT = 0.7Twb + 0.2Tbg + 0.1Tdb Reading Comments Low risk still exists Level inc as progress through day At-risk should not compete Reschedule, delay, or high alert Roberts W. 1998; Medical Manual. NATA • <18oC (<65oF) • 18-23oC (65-73oF) • 23-28oC (73-82oF) • >28oC (>82oF)

  7. Mild Heat Illness Symptom Scale 0-10 scale with anchors • Feeling tired • Cramps • Nausea • Dizziness • Thirst • chills • Vomiting • Confusion • Muscle weakness • Heat sensations • Feeling lightheaded Low-risk positions: QB, P, K Mid-risk positions: DB, RB, LB, R Coris E, et al. SMJ; 2006. High-risk positions: OL, DL

  8. Exertional Heat Illness Exertional Cases Management Elevation of legs/keep dry Sports drinks, IV Shade, rehydrate Cool, shade, rehydrate Immersion, transport Transport, IV • Heat edema/rash • Muscle cramps • Syncope • Exhaustion • Stroke • Hyponatremia Rectal temp* Return is possible for the first 4, and gradual for last 2

  9. PARRIS ISLAND MARINE CORPS RECRUIT TRAINING DEPOT, SC

  10. PARRIS ISLAND MARINE CORPS RECRUIT TRAINING DEPOT, SC

  11. Volleyball Pre-season 2009

  12. Should we develop a formal index for risk? • Risk Factors • High fat • Low fitness • Past Hx • Not acclimatized • Dehydration • Meds/Supplem* • Heavy clothing • Fever or illness • Sunburn/skin • Prepubescent • Over-exertion • Stoic • CV disease • Sickle-cell trait Antihistamines Antipsychotic Antidepressant Diuretics Ergogenic stimulants betablockers Previous day WBGT Dark colored clothing

  13. Risk Assessment Matrix • WBGT • # days Cat 5 • Past work load • Work load today • Acclimatization d • Rest in past day • Category 4-5 • >4 • Hard • Hard • <3 • <2 h Adjusted 7-13=extreme risk Hard Work = speed >7 mph, resistance >70% max US Army 2009

  14. Matrix Actions • Know the players • Individual risk factors • Check hydration status • Do after each practice • Require extra fluids as needed • Check urine color • Check illness and Meds

  15. Should ATs be trained in IV administration? • Heat cramps • Heat syncope • Exercise exhaustion • Exertional hyponatremia Emerson C, et al. Unpublished FIU; 2006.

  16. Is rectal temp necessary? • Oral • Tympanic • Axillary • Skin Casa D. JAT. 2007; 42:333-342

  17. How far should we go to measure sweat rate? • NATA recommends calculating sweat rate on each athlete: • (BWpre – BWpost + fluid in – urine vol)/ex time) • Do this for a variety of environmental conditions, practices, competition • 95% CI reported 0.5-2.5 L/h Casa D, et al. JAT. 2008; 42:333-342

  18. Thanks!

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