SCI Energy Systems & Exercise Physiology 1 — Questions and Answers
Question 1: Which of the following correctly identifies the three primary energy systems used during exercise?
- Phosphagen, Glycolytic, and Oxidative (Correct answer)
- Anaerobic, Lactic, and Mitochondrial
- Aerobic, Alactic, and Phosphate
- Creatine, Glucose, and Oxygen systems
Correct answer: Phosphagen, Glycolytic, and Oxidative
The three primary energy systems are the phosphagen (ATP-PCr), glycolytic (lactic acid), and oxidative (aerobic) systems, each dominating at different exercise intensities and durations.
Question 2: Which energy system provides ATP most rapidly but is limited to only 8–10 seconds of maximal effort?
- Oxidative system
- Glycolytic system
- Phosphagen (ATP-PCr) system (Correct answer)
- Gluconeogenesis pathway
Correct answer: Phosphagen (ATP-PCr) system
The phosphagen system uses stored ATP and phosphocreatine to generate energy almost instantaneously but is depleted within 8–10 seconds of all-out effort.
Question 3: At low-to-moderate exercise intensities, the aerobic energy system primarily relies on which substrate?
- Protein
- Fat (free fatty acids) (Correct answer)
- Phosphocreatine
- Lactate only
Correct answer: Fat (free fatty acids)
At low-to-moderate intensities, fat (free fatty acids) is the predominant fuel for the aerobic energy system due to its high energy yield per gram.
Question 4: VO2 max is best defined as the:
- Maximum heart rate achievable during intense exercise
- Maximum rate of oxygen consumption during intense exercise (Correct answer)
- Volume of air exhaled per minute at peak effort
- Maximum blood lactate level tolerated during exercise
Correct answer: Maximum rate of oxygen consumption during intense exercise
VO2 max is the maximal rate at which the body can consume and utilize oxygen during intense exercise, and is the gold standard measure of aerobic capacity.
Question 5: The lactate threshold is best described as the exercise intensity at which:
- Muscles begin to use oxygen for the first time
- Blood lactate concentration rises faster than it can be cleared (Correct answer)
- The heart reaches its maximum rate
- Fat oxidation stops completely
Correct answer: Blood lactate concentration rises faster than it can be cleared
The lactate threshold is the point where lactate production exceeds the body's clearance capacity, causing blood lactate to accumulate and signaling a shift toward anaerobic metabolism.
Question 6: During a 10-second all-out sprint on an indoor cycling bike, which energy system contributes the most ATP?
- Oxidative phosphorylation
- Glycolysis
- Phosphagen (ATP-PCr) system (Correct answer)
- Beta-oxidation
Correct answer: Phosphagen (ATP-PCr) system
A 10-second maximal sprint is powered almost entirely by the phosphagen system, which uses stored ATP and phosphocreatine in the muscle.
Question 7: Cardiac output during exercise is calculated as:
- Heart rate × stroke volume (Correct answer)
- Heart rate × blood pressure
- Stroke volume ÷ heart rate
- VO2 max × body weight
Correct answer: Heart rate × stroke volume
Cardiac output equals heart rate multiplied by stroke volume, representing the total volume of blood the heart pumps per minute.
SCI Energy Systems & Exercise Physiology 1
Which of the following correctly identifies the three primary energy systems used during exercise?