CSN Hydration & Fluid Balance

Question 1

Which electrolyte is lost in the greatest concentration through sweat and must be prioritized in a sports hydration plan?

Accepted Answer

Sodium

Answer

Sodium is the predominant electrolyte in sweat, with losses ranging from 460–1840 mg per liter, making it the primary electrolyte to replace during and after exercise.

Question 2

A urine specific gravity of 1.020–1.030 in an athlete prior to competition most likely indicates:

Accepted Answer

Mild dehydration

Answer

A urine specific gravity above 1.020 indicates the kidneys are concentrating urine due to inadequate fluid intake, reflecting mild to moderate dehydration.

Question 3

At what level of body weight loss from sweat does aerobic exercise performance begin to measurably decline?

Accepted Answer

2%

Answer

Research consistently shows that a body weight loss of approximately 2% from sweat leads to measurable decreases in aerobic performance, thermoregulation, and cognitive function.

Question 4

Which of the following best describes the condition of hyponatremia in athletes?

Accepted Answer

Low blood sodium typically caused by excessive plain water intake during prolonged exercise

Answer

Exercise-associated hyponatremia occurs when serum sodium drops below 135 mEq/L, most commonly from drinking excessive amounts of plain water that dilute blood sodium levels.

Question 5

According to ACSM guidelines, how much fluid should an athlete consume in the 2–4 hours before exercise to ensure pre-hydration?

Accepted Answer

5–7 mL per kg of body weight

Answer

ACSM recommends consuming 5–7 mL of fluid per kg of body weight in the 2–4 hours before exercise to achieve adequate pre-exercise hydration.

CSN - Certified Sports Nutritionist Practice Test

CSN - Certified Sports Nutritionist Practice Test

CSN Hydration & Fluid Balance