CSSD Hydration Strategies 3 — Questions and Answers
Question 1: Which fluid is most effective for rapid rehydration after a 90-minute soccer match where ~2% body weight was lost?
- Plain water at 150% of losses
- Oral rehydration solution (ORS) with sodium and glucose at 150% of losses (Correct answer)
- Caffeinated sports drink at 100% of losses
- Milk at 50% of losses
Correct answer: Oral rehydration solution (ORS) with sodium and glucose at 150% of losses
An ORS providing sodium and glucose at 150% of fluid losses accelerates rehydration by retaining more fluid and replacing electrolytes.
Question 2: During a 4-hour ultramarathon, an athlete's serum sodium drops to 128 mEq/L with no symptoms. According to current guidelines, what is the appropriate intervention?
- IV saline bolus immediately
- Fluid restriction and sodium-rich foods until symptoms resolve or sodium normalizes (Correct answer)
- Aggressive oral sodium supplementation regardless of fluid intake
- Continue racing with no modification
Correct answer: Fluid restriction and sodium-rich foods until symptoms resolve or sodium normalizes
Asymptomatic EAH is managed conservatively with fluid restriction and sodium replacement; IV fluids are reserved for symptomatic cases with altered mental status.
Question 3: Which hormone plays the primary role in regulating water reabsorption in the kidneys during exercise-induced dehydration?
- Aldosterone
- Antidiuretic hormone (ADH/vasopressin) (Correct answer)
- Renin
- Atrial natriuretic peptide (ANP)
Correct answer: Antidiuretic hormone (ADH/vasopressin)
ADH is released from the posterior pituitary in response to increased plasma osmolality, promoting water reabsorption in the collecting ducts.
Question 4: A CSSD recommends glycerol hyperhydration to a cyclist before a 3-hour road race in the heat. What is the primary physiological rationale?
- Glycerol increases fat oxidation, sparing glycogen
- Glycerol acts as an osmotic agent, expanding plasma and total body water (Correct answer)
- Glycerol reduces perceived exertion by acting as a CNS stimulant
- Glycerol improves sodium absorption in the gut
Correct answer: Glycerol acts as an osmotic agent, expanding plasma and total body water
Glycerol is an osmotically active substance that, when co-ingested with fluid, promotes water retention and expands plasma volume before exercise.
Question 5: How should a CSSD calculate an athlete's individualized fluid intake target during exercise?
- A fixed 500 mL/hour for all athletes
- Based on sweat rate testing: fluid intake ≈ sweat rate − acceptable deficit (no more than 2% BW) (Correct answer)
- Drink until urine is clear regardless of intake volume
- Match fluid intake exactly to sweat rate to maintain body weight
Correct answer: Based on sweat rate testing: fluid intake ≈ sweat rate − acceptable deficit (no more than 2% BW)
Individualized fluid targets are based on measured sweat rate, with intake adjusted to prevent losses exceeding 2% body weight while avoiding overdrinking.
Question 6: Which scenario represents the greatest risk for exercise-associated hyponatremia (EAH)?
- A 75 kg male completing a 10 km race in 45 minutes in cool weather
- A 55 kg female completing a 6-hour triathlon, drinking 1 L/hour of plain water (Correct answer)
- A 90 kg male consuming a sodium-electrolyte drink at 600 mL/hour for 2 hours
- A recreational cyclist riding 1 hour with 400 mL sports drink
Correct answer: A 55 kg female completing a 6-hour triathlon, drinking 1 L/hour of plain water
Smaller body mass, prolonged duration, and high intake of hypotonic fluid dramatically increase EAH risk in this scenario.
Question 7: Compared to water, what advantage does low-fat chocolate milk offer for post-exercise rehydration?
- Lower caloric density, reducing weight gain
- Combined protein, carbohydrate, sodium, and fluid promote rehydration and muscle repair simultaneously (Correct answer)
- Faster gastric emptying due to its liquid composition
- Lower osmolality than most sports drinks
Correct answer: Combined protein, carbohydrate, sodium, and fluid promote rehydration and muscle repair simultaneously
Chocolate milk provides carbohydrate for glycogen resynthesis, protein for muscle repair, and sodium/fluid for rehydration, making it a multi-purpose recovery beverage.
CSSD Hydration Strategies 3
Which fluid is most effective for rapid rehydration after a 90-minute soccer match where ~2% body weight was lost?