Exercise Physiology & Energy Metabolism Flashcards

What is the approximate ATP yield from the complete oxidation of one mole of palmitate (16-carbon saturated fatty acid)?

Answer: 129 ATP

Palmitate oxidation yields approximately 129 ATP through combined beta-oxidation (producing NADH and FADH2) and subsequent oxidative phosphorylation of resulting acetyl-CoA in the TCA cycle.

An athlete complains of 'hitting the wall' at mile 20 of a marathon. This phenomenon is primarily attributed to:

Answer: Near-depletion of liver and muscle glycogen stores

The 'wall' corresponds to glycogen depletion forcing greater reliance on fat oxidation, which cannot sustain race pace, resulting in a dramatic reduction in running speed.

Which statement BEST describes muscle fiber recruitment during progressive increases in exercise intensity?

Answer: Type I fibers are recruited first, with Type IIa and IIx added as intensity increases (size principle)

Henneman's size principle dictates that smaller, fatigue-resistant Type I motor units are recruited first, with larger Type II units added as force demands increase.

During prolonged exercise in the heat, which combination of stressors MOST compromises muscle glycogen sparing?

Answer: Hyperthermia and dehydration

Hyperthermia accelerates glycogenolysis and dehydration increases circulating catecholamines and reduces hepatic glucose output, together accelerating glycogen depletion.

What is the primary nutritional strategy to maximize muscle glycogen supercompensation before an endurance event?

Answer: 3–4 days of high carbohydrate intake (8–12 g/kg/day) combined with exercise taper

Current evidence supports 3–4 days of high carbohydrate intake (8–12 g/kg/day) paired with exercise tapering to maximize glycogen stores prior to competition.

The lactate threshold (LT1) is physiologically defined as the exercise intensity at which:

Answer: Lactate production first exceeds lactate clearance, causing a sustained rise above resting levels

LT1 marks the intensity where lactate production begins to outpace clearance, resulting in the first sustained elevation above baseline (~1–2 mmol/L).

A sports dietitian notes that a cyclist's fat max (FATmax) occurs at 55% VO2max. How should this information guide fueling recommendations?

Answer: Use this intensity as the upper anchor for low-carbohydrate recovery rides and fat-adaptation training blocks

FATmax identifies the optimal intensity for maximal fat oxidation, informing periodized fueling strategies where lower-carbohydrate availability during recovery or base rides can enhance fat-burning adaptations.