Exercise Physiology Chapter 4 Exercise Metabolism

At rest, almost 100% of the energy required to sustain bodily functions is provided by _____.

At rest, almost 100% of the energy required to sustain bodily functions is provided by _____.

aerobic metabolism

Rank the bioenergetic pathways in the order in which they are utilized at the onset of exercise.

1. ATP-PC system
2. Glycolysis
3. Aerobic energy production

During a three-minute bout of exercise, it is seen that _____ was already contributing ATP during the first minute of exercise, and it increased during the second minute.

glycolysis

T/F Rest-to-work transitions involve only one bioenergetic pathway at a time.

false.

The major point concerning the bioenergetics of rest-to-work transitions is that several metabolic systems are involved. The energy needed for exercise is provided by several metabolic systems operating with overlaps.

Which of the terms applies to the lag in oxygen uptake at the beginning of exercise?

Oxygen deficit

During resting conditions, a healthy human body's energy requirement is _____.

constant

The _____ does not fall instantaneously from the steady-state value measured during the exercise to the resting-state value that can be associated with standing by a treadmill.

Metabolic rate

When O2 consumption does not increase instantaneously to a steady-state value, _____ energy sources contribute to the overall ATP production at the beginning of an exercise.

anaerobic

Which of the following factors are influenced by the intensity of an exercise? (Check all that apply.)

- The duration of an elevated post-exercise metabolic rate
- The magnitude of an elevated post-exercise metabolic rate

The effectiveness of the ATP-PC system and glycolysis in the first minutes of exercise of a three-minute exercise bout is such that ATP levels in the muscle are virtually _____.

unchanged

Historically, the term ______ _______ has been applied to the elevated oxygen uptake (above resting levels) following exercise.

oxygen debt

As the steady-state oxygen consumption is reached, the body's ATP requirement is met by _____.

aerobic metabolism

Oxygen deficit can be specifically defined as the difference between _____ in the first few minutes of exercise and an equal time period after steady state has been obtained.

oxygen uptake

The _____ phase of oxygen debt, which lasts approximately two-three minutes, immediately follows an exercise.

rapid

T/F The metabolic rate of an individual remains elevated for several minutes immediately following an exercise.

true.

The metabolic rate of an individual remains elevated for several minutes immediately following an exercise. For several minutes after exercise, the oxygen uptake is above the level needed to meet the demands of standing still after the exercise.

It was believed that the slow portion of the oxygen debt was due to the oxidative conversion of _____ to glucose in the liver.

lactate

The magnitude and duration of the elevated post-exercise metabolic rate (VO2) is influenced by the _____.

intensity of exercise

According to A. V. Hill, the excess oxygen consumed following exercise was repayment for the _____ incurred at the onset of exercise.

oxygen deficit

The process of glucose synthesis from non-carbohydrate sources is known as _____.

gluconeogenesis

The factor responsible for excess post-exercise oxygen consumption (EPOC) is consistent with the classic view of the _____ portion of oxygen debt where O2 consumed immediately following exercise is used to restore PC and O2 stores.

rapid

The slow phase of oxygen debt can persist greater than _____ after exercise.

30 minutes

T/F Higher blood lactate levels during high-intensity exercise indicate that less O2 is required for lactate conversion to glucose in gluconeogenesis.

false.

Higher blood lactate levels indicate that more O2 is required for lactate conversion to glucose in gluconeogenesis

According to earlier beliefs, the rapid portion of the O2 debt represented the oxygen that was required to resynthesize stored _____ and replace tissue stores of oxygen.

ATP-PC

The energy to perform a short-term exercise of high intensity is produced primarily from _____.

Anaerobic metabolic pathways

An intense exercise that lasts longer than 5 seconds begins to utilize the ATP-producing capability of _____.

glycolysis

Oxygen debt is also known as _____.

excess post-exercise oxygen consumption

The energy to perform a long-term exercise for more than ten minutes is produced primarily from _____.

Aerobic metabolism

A contributing factor to excess post-exercise oxygen consumption (EPOC) is that _____ remain elevated above resting levels for several minutes following exercise, which requires additional O2.

Breathing and heart rate

Prolonged exercise in a _____ environment leads to a "drift" upward of oxygen uptake. Therefore, a steady-state oxygen uptake is not maintained.

hot/humid

Identify the reasons why excess post-exercise oxygen consumption (EPOC) is greater during high-intensity exercise when compared to moderate-intensity exercise

- Phosphocreatine (PC) is depleted to a greater extent.
- Higher blood lactate levels

Incremental exercise tests are also known as ___ ______ ___ and are often employed by physicians to examine patients for possible heart disease.

graded exercise tests

ATP production is dominated either by the ATP-PC system or glycolysis depending primarily on the _____ the activity.

length of

During a high-intensity, short-term exercise, which lasts 1 to 5 seconds, the muscle's ATP production is dominated by the _____.

ATP-PC system

Incremental exercise tests are usually conducted using _____.

treadmill or cycle ergometer

In the context of prolonged exercise, a steady-state oxygen uptake can generally be maintained during submaximal, _____ exercise.

moderate-intensity

The maximal capacity to transport and utilize oxygen during exercise is known as (VO2 max)

maximal oxygen uptake

Continuous exercise at a high relative work rate greater than _____ results in a slow rise in oxygen uptake across time. Therefore, a steady state cannot be maintained during such an exercise.

75% VO2 max

During an incremental exercise test on a cycle ergometer, oxygen uptake increases as a(n) _____ function of the work rate until VO2 max is reached.

linear

Exercise scientists use incremental exercise tests to determine a subject's _____.

Cardiovascular fitness

The maximum ability of the cardiorespiratory system to deliver oxygen to the _____ is known to influence VO2 max.

contracting muscle
(contracting tissue)

Before the term lactate threshold was widely adopted, a common term used to describe the point of a systematic rise in blood lactate during incremental exercise was the _____ ______

anaerobic threshold

T/F incremental exercise tests involve increasing the work rate by decreasing the incline on a treadmill.

false.
Incremental exercise tests involve an increase in work rate by increasing either the speed or the incline on a treadmill.

_____ is specifically defined as the exercise intensity or oxygen consumption at which a specific blood lactate concentration is reached.

onset of blood lactate accumulation

Measuring the _____ is considered by many exercise scientists to be the most valid measurement of cardiovascular fitness of a subject.

VO2 max

Slow muscle fibers contain an LDH isozyme that promotes the formation of _____.

Pyruvate

When VO2 max is reached during a graded exercise test, an increase in power output _____.

does not lead to an increase in oxygen uptake

A noninvasive technique to estimate the percent contribution of carbohydrate or fat to energy metabolism during an exercise is the _____ ______ _____which is defined as the ratio of carbon dioxide output (VCO2) to the volume of oxygen consumed (VO2).

Respiratory exchange ratio

A factor that influences VO2 max depends on the muscle's ability to _____.

take up oxygen and produce ATP aerobically

Match the types of oxidation to their respective respiratory exchange ratio (R) values

Fat oxidation - 0.7
Carbohydrate oxidation - 1.0

As the exercise intensity increases, blood levels of _____ begin to rise in an exponential fashion.

Lactate

The higher the respiratory exchange ratio (R) value, the greater is the role of _____ as an energy source.

carbohydrate

The more widely adopted term for the sudden rise in lactate levels in the blood is the ____ _____, which was known as anaerobic threshold previously

lactate threshold

Match the types of muscle fiber to their specific roles during exercise

Fast fibers - recruited during intense, rapid exercise
Slow fibers - recruited primarily during low-intensity exercise

_____ contribute to less than 2% of the substrate used during exercise of less than one hour's duration.

proteins

During steady-state conditions, the VCO2/VO2 ratio is called the respiratory quotient, as it is thought to reflect the CO2 production and O2 consumption by the _____ of the active muscles.

mitochondria

As the exercise intensity increases above the crossover point, a progressive shift occurs from _____ metabolism.

fat to carbohydrate

The subject should reach a steady state for _____ to be used as an estimate of substrate utilization as only during the steady-state are VCO2 and VO2 reflective of O2 uptake and CO2 production in the tissues.

Respiratory exchange ratio (R)

Recruitment of fast twitch fibers causes a shift from fat to _____ metabolism.

Carbohydrate

The lower the respiratory exchange ratio (R) value, the greater is the contribution of _____ toward generating energy.

Fat

High levels of epinephrine increase _____ activity, which causes an increase in muscle glycogen breakdown. This leads to an increased rate of glycolysis and lactate production.

Phosphorylase

Low-intensity exercise relies primarily on _____ as fuel for energy production.

fats

The rate of fat metabolism during prolonged exercise can be controlled by enzymes called _____.

Lipases

As the exercise intensity increases, there is an intensity at which the energy derived from carbohydrate exceeds that of fat. This work rate has been labeled as the _____.

Crossover point

Epinephrine is known to increase _____ activity thereby causing an increase in blood and muscle levels of FFA.

lipase

Fast twitch fibers have an abundance of _____ that make them better equipped to perform their function.

glycolytic enzymes

Depletion of muscle and blood carbohydrate stores results in _____.

muscular fatigue

A nonprotein respiratory exchange ratio (R) value of _____ represents a condition wherein fat and carbohydrate contribute equally as energy substrates.

0.85

Depletion of available muscle carbohydrate reduces the rate of glycolysis, and therefore the concentration of _____ in the muscle is also reduced. This lowers ATP production, and in turn, increases muscular fatigue

Pyruvate

The increased production of lactate inhibits _____ metabolism by reducing its availability as a substrate, thereby resulting in the use of carbohydrate as the primary fuel for the working muscles.

fat

When _____ stores are depleted in the body, the rate at which fat is metabolized is also reduced.

carbohydrate

Which of the following hormones stimulate lipase activity?

Norepinephrine
Epinephrine
Glucagon

T/F Muscle glycogen stores in the body provide a direct source of carbohydrate for muscle energy metabolism.

true.
Muscle glycogen stores in the body provide a direct source of carbohydrate for muscle energy metabolism.

During low-intensity, prolonged exercise, blood levels of _____ rise.

epinephrine

During the first hour of submaximal prolonged exercise, much of the carbohydrate metabolized by the muscle comes from _____.

glycogen

During prolonged exercise of more than two hours, the muscle and liver stores of _____ can reach very low levels.

glycogen

When an individual consumes more food than he or she can expend, this additional energy is stored in the form of _____.

fat

A decrease in glycolysis lowers the rate of aerobic production of ATP by reducing the number of _____ intermediates. This limits muscular performance and may cause fatigue.

Kreb's cycle

At higher exercise rates, metabolism of muscle _____ increases for energy generation.

triglycerides

A reduction in glycogen stores also causes a diminished rate of ATP production from _____ metabolism which specifically requires oxidation via the Kreb's cycle.

fat

In the liver, the amino acid _____ can be converted to glucose and returned via the blood to skeletal muscle to be utilized as a substrate for producing energy.

alanine

_____ glycogen stores mainly serve as a means of replacing blood glucose levels.

Liver

Which of the following energy sources play a greater role during low-intensity exercise?

Blood glucose

During prolonged exercise of more than two hours, enzymes capable of degrading muscle proteins called _____ are activated.

proteases

Most fat in the body is stored in the form of _____ in adipocytes.

triglycerides

The concept that lactate can be produced in one tissue and then transported to another to be used as an energy source has been termed the _____.

lactate shuttle

The primary source of fat as an energy source during low-intensity exercise is plasma _____.

free fatty acids

During exercise, the skeletal muscle can directly metabolize _____ amino acids such as valine, leucine, and isoleucine to produce ATP.

Branched-chain

T/F Muscle glycogen stores in the body provide a direct source of carbohydrate for muscle energy metabolism.
True false question.

true.
Muscle glycogen stores in the body provide a direct source of carbohydrate for muscle energy metabolism.

The activation of enzymes capable of degrading muscle proteins during prolonged exercise, appears to be due to exercise-induced increases in cellular levels of _____ within the muscle fibers.

calcium

In slow skeletal muscle fibers and the heart, lactate removed from the blood can be converted to pyruvate and, in turn, _____ which can then enter the Kreb's cycle and contribute to oxidative metabolism.

Acetyl-CoA