Sports Nutrition & Exercise Performance Flashcards

During high-intensity exercise lasting less than 10 seconds, which energy system is primarily used?

Answer: Phosphocreatine (ATP-PCr) system

The ATP-PCr system provides immediate, anaerobic energy for maximal efforts lasting up to approximately 10 seconds by resynthesizing ATP from stored phosphocreatine.

What is the recommended carbohydrate intake per hour for endurance athletes during exercise lasting longer than 90 minutes?

Answer: 30–60 g/hr

Research supports consuming 30–60 g of carbohydrates per hour during prolonged endurance exercise to maintain blood glucose and spare muscle glycogen.

Which type of muscle fiber is most reliant on aerobic metabolism and is highly resistant to fatigue?

Answer: Type I

Type I (slow-twitch) fibers have high mitochondrial density and capillary supply, making them primarily aerobic and highly fatigue-resistant.

Carbohydrate loading (glycogen loading) is most beneficial for which type of athletic event?

Answer: Endurance events lasting more than 90 minutes

Carbohydrate loading maximizes muscle glycogen stores and benefits events where glycogen depletion limits performance—typically those lasting beyond 90 minutes.

What is the primary role of branched-chain amino acids (BCAAs) during prolonged endurance exercise?

Answer: Serving as an energy substrate and potentially reducing central fatigue

BCAAs can be oxidized for energy during prolonged exercise and may reduce central fatigue by competing with tryptophan for transport across the blood-brain barrier, limiting serotonin production.

Which macronutrient becomes the predominant fuel source during low-to-moderate intensity, prolonged aerobic exercise?

Answer: Fat

During low-to-moderate intensity aerobic exercise, fat via beta-oxidation is the predominant fuel source, providing sustained energy over long durations at a slower rate.

What concept describes the exercise intensity at which the body shifts from predominantly fat to predominantly carbohydrate metabolism?

Answer: Crossover concept

The crossover concept describes the exercise intensity at which carbohydrate-derived fuels become the predominant energy source, crossing over fat as the primary fuel.