Hydration & Fluid Balance Flashcards

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

Answer: Sodium

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.

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

Answer: Mild dehydration

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

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

Answer: 2%

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

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

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

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.

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

Answer: 5–7 mL per kg of body weight

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.

An athlete's sweat rate is best estimated using which method?

Answer: Measuring body weight before and after exercise accounting for fluid intake and urine output

Sweat rate is calculated by comparing pre- and post-exercise body weight, adding fluid consumed, and subtracting any urine output, then dividing by exercise duration.

Which urine color on the urine color chart (1–8 scale) is generally considered to indicate adequate hydration for athletes?

Answer: Colors 1–3 (pale yellow to light yellow)

A urine color of 1–3 (pale to light yellow) is the target range for adequate hydration; colors above 3 typically suggest increasing dehydration.