Exercise Physiology and Metabolism Flashcards

A client performs a set of heavy barbell squats for 5 repetitions, lasting approximately 15-20 seconds. Which energy system is predominantly being used to supply ATP for this activity?

Answer: ATP-PC (Phosphagen) system

The ATP-PC (Phosphagen) system provides immediate energy for high-intensity, short-duration activities. It utilizes stored ATP and phosphocreatine to rapidly regenerate ATP without the need for oxygen. This system is dominant for activities lasting up to about 10-20 seconds, such as heavy lifting for low repetitions or short sprints.

During a 45-minute steady-state run at a moderate intensity (65% VO2 max), what is the primary fuel source the body will utilize for energy?

Answer: Fatty acids

During prolonged, moderate-intensity aerobic exercise, the body primarily relies on the oxidation of fatty acids to produce ATP. While carbohydrates (muscle glycogen and blood glucose) are also used, fat becomes the predominant fuel source as the duration increases. Amino acids contribute minimally to energy production during exercise of this nature.

A client new to resistance training completes a challenging workout. For the next 24-38 hours, they experience a slight elevation in their resting metabolic rate. This phenomenon is best described as:

Answer: Excess Post-exercise Oxygen Consumption (EPOC)

Excess Post-exercise Oxygen Consumption (EPOC), often called the 'afterburn effect,' is the increased rate of oxygen uptake following strenuous activity. This elevated metabolism helps the body restore itself to its pre-exercise state by replenishing fuel stores, repairing muscle tissue, and rebalancing hormones, resulting in additional calorie expenditure after the workout is finished.

Which of the following metabolic adaptations is most associated with consistent, high-intensity interval training (HIIT)?

Answer: Increased tolerance to lactate accumulation

High-intensity interval training repeatedly pushes the body to work anaerobically, leading to the production of lactate and hydrogen ions. A key adaptation to this type of training is an improved ability to buffer and clear lactate from the muscles. This increased lactate tolerance allows an individual to sustain higher intensities for longer before fatigue sets in.

A client performs a 400-meter sprint which takes them approximately 60 seconds to complete. The primary byproduct of the dominant energy system used during this event, which is associated with muscle fatigue, is:

Answer: Lactic acid

An all-out 400-meter sprint relies heavily on the glycolytic system for ATP production. This system breaks down glucose and glycogen anaerobically. A byproduct of this rapid process is the formation of pyruvate, which, in the absence of sufficient oxygen, is converted to lactic acid. The accumulation of hydrogen ions associated with lactic acid contributes to muscle fatigue.

Which acute hormonal response is typically observed immediately following a high-intensity resistance training session?

Answer: An increase in circulating testosterone and growth hormone

High-intensity exercise, including resistance training and HIIT, acts as a significant physiological stressor that stimulates the endocrine system. Acutely, this leads to an increase in anabolic hormones such as testosterone and growth hormone, which are involved in muscle repair and growth. Cortisol, a stress hormone, also typically increases during and immediately after the session, not decreases.