CSSD Exercise Physiology & Energy Metabolism 2

Question 1

During high-intensity interval training (HIIT), which metabolic byproduct accumulates and contributes to peripheral fatigue?

Accepted Answer

Lactate and hydrogen ions

Answer

Lactate accumulation alongside hydrogen ions (not lactate itself) lowers intracellular pH, impairing muscle contractile function during high-intensity exercise.

Question 2

The crossover concept in exercise physiology describes the point at which:

Accepted Answer

Fat oxidation decreases and carbohydrate oxidation becomes the dominant fuel source

Answer

The crossover concept (Brooks & Mercier) describes the exercise intensity at which carbohydrate oxidation exceeds fat oxidation as the predominant fuel source.

Question 3

Which enzyme is rate-limiting for beta-oxidation of fatty acids in skeletal muscle?

Accepted Answer

Carnitine palmitoyltransferase I (CPT-I)

Answer

CPT-I controls fatty acid transport into the mitochondrial matrix and is the rate-limiting step for beta-oxidation; it is inhibited by malonyl-CoA at high carbohydrate flux.

Question 4

An athlete exercising at 65% VO2max for 90 minutes is MOST likely experiencing:

Accepted Answer

Progressive reliance on plasma free fatty acids as muscle glycogen declines

Answer

As muscle glycogen declines during prolonged moderate-intensity exercise, plasma free fatty acid uptake and oxidation progressively increase to spare remaining glycogen.

Question 5

What is the primary role of AMP-activated protein kinase (AMPK) during exercise?

Accepted Answer

Sense energy depletion and stimulate glucose uptake and fat oxidation

Answer

AMPK is activated when the AMP:ATP ratio rises, signaling low energy status and triggering pathways that increase glucose uptake (GLUT-4 translocation) and fatty acid oxidation.

(CSSD) Board Certified Specialist in Sports Dietetics Practice Test

(CSSD) Board Certified Specialist in Sports Dietetics Practice Test

CSSD Exercise Physiology & Energy Metabolism 2