AFAA Personal Trainer Certification Practice Exam

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Study for the AFAA Personal Trainer Certification Exam. Engage with quizzes, flashcards, and multiple-choice questions. Prepare efficiently with hints and explanations to achieve certification success.

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Which energy system is activated during high-intensity activities lasting no longer than 15-20 seconds?

Aerobic system
Phosphagen system
Anaerobic glycolytic system
Oxidative system

The correct answer is: Phosphagen system

The phosphagen system is primarily responsible for providing immediate energy during high-intensity activities that last up to 15-20 seconds. This energy system utilizes adenosine triphosphate (ATP) and creatine phosphate (CP) stored in the muscles to rapidly regenerate ATP, which is crucial for short bursts of explosive activity, such as sprinting or heavy lifting. Because these activities require a quick supply of energy and exceed the capacity of aerobic processes, the phosphagen system is the predominant source of energy in such scenarios. In contrast, other energy systems are engaged during different durations and intensities of exercise. The aerobic system operates at a slower pace and involves oxygen to produce energy over a longer duration, while the anaerobic glycolytic system kicks in for activities lasting longer than 20 seconds but shorter than about two minutes. The oxidative system is utilized for extended, lower-intensity activities, relying on oxygen as the primary fuel source. Therefore, when considering activities that are brief yet intense, the phosphagen system is the correct answer.