Exercise Physiology Exam 3

effect of endurance training or detraining on mitochondria volume in human skeletal muscle

- Seven days of detraining can reduce mitochondrial volume by 50% below the trained level - Five weeks of endurance training can increase skeletal muscle mitochondrial volume by two times about normal. - After a period of detraining, approximately 4 weeks of retraining is required to regain the lost mitochondrial volume.

At high environmental temperatures, which of the following variables impact the amount of heat loss by evaporation

- amount of exposed skin - ambient temperature and relative humidity - convective currents

Regulation of body core temperature is important because

- cellular structures and metabolic pathways are affected by temperature -high temperature can alter the structure and function of enzymes -low temperatures can promote abnormal cardiac function (e.g., arrhythmias)

Cold acclimation results in which physiological adaptations

- improved ability to prevent large decreases in skin temperature during cold exposure -increased nonshivering thermogenesis -improved ability to sleep in cold environments

A high H+ concentration can contribute to fatigue by

- inhibiting Ca++ release from the sarcoplasmic reticulum - interfering with Ca++ binding to troponin - reducing the force generated per cross-bridge

To ensure adequate hydration, athletes should

- monitor fluid loses during exercise -consume fluids every 15-20 minutes during exercise -consume fluids (after exercise) equal to approximately 150% of weight loss

a healthy individual at sea level and at rest - arterial blood

- oxygen content of 20 mlO2/100 ml blood -PO2 of approximately 100 mmHg -oxyhemoglobin saturation of 97-98%

important function of the pulmonary system

- regulation of acid base balance during exercise - to provide an interface for gas exchange between the external environment and the body

contributors to neural drive

- total number of motor units activated - the firing rate of the motor neuron -motor unit synchronization

hemoglobin's buffering capacity

-Hemoglobin has six times the buffering capacity of plasma proteins because of it's concentration -Deoxyhemoglobin is a better buffer than oxyhemoglobin

changes in ventilatory patterns during exercise

-Increasing tidal volume during exercise ensures that dead space ventilation remains small -Changes in breathing patterns during exercise are designed to reduce the risk of respiratory muscle fatigue -Changes in breathing patterns during exercise are important to ensure that optimal mechanics of breathing are realized during exercise

skeletal muscle buffer systems

-Two monocarboxylate transporters exist in human skeletal muscle fibers -High intensity exercise training has been reported to improve muscle buffer capacity by increasing both carnosine and hydrogen ion transporters in skeletal muscle

Prolonged inactivity of skeletal muscle leads to rapid muscle atrophy; this occurs due to:

-a decrease in muscle protein synthesis -increased protein breakdown in muscle fibers

Myoglobin

-exists in relatively large quantities in slow twitch muscle fibers -binds oxygen shuttles oxygen from the cell membrane to the mitochondria

has the ability to impact the risk of developing heat injury during exercise

-hydration status -acclimatization -wind

gas exchange in the lungs occurs

-in the respiratory zone -across approximately 300 million alveoli

contribute to the endurance exercise training-induced improvement in stroke volume during exercise

-increase EDV -increased cardiac contractility -decrease in total peripheral resistance

Individuals who are successful climbing to high altitudes have a great capacity to hyperventilate. Hyperventilation results in

-left shift in the oxyhemoglobin dissociation curve -decrease in arterial pH -higher PO2 in the blood

In aerobic performances lasting 3 to 20 minutes, which factors contribute to performance?

-maximal cardiac output -fiber type -VO2 max

Increased production of radicals in skeletal muscles during periods of prolonged inactivity (prolonged bedrest) and promotes muscle atrophy because

-oxidative stress activates proteases in muscle fibers -oxidative stress decreases protein synthesis in muscle fibers -oxidative stress prevents mTOR activation

heat shock proteins

-stabilize and refold damaged cellular proteins -Repeated bouts of exercise in warm or hot environments increase their synthesis in cells -assist cells in tolerating heat stress

sex differences in breathing

-when matched for age and body weight, women have smaller airways compared tot men -the energy requirements for breathing during exercise is higher for women compared to men

range of values represents "good" air quality as indicated by the Air Quality Index (AQI)

0-50

Calculate the total evaporation of sweat necessary to prevent heat gain in the body given the following information:Total body energy expenditure = 250 KcalExercise efficacy = 20%Evaporation of 1000 ml of sweat results in 580 Kcal of heat lossTherefore, the total evaporation of sweat necessary to prevent body heat gain in these conditions is:

0.344 L

muscle pH is generally

0.4-0.6 pH units lower than arterial pH

Human fat tissue is predicted to have a density of ____ whereas fat-free tissue (i.e., skeletal muscle) is predicted to have a density of __

0.9 g/ml; 1.1g/ml

Endurance exercise training programs (e.g., 3 days/week @ 60% VO2 max for 12 weeks) typically results in a ______.

15-25% improvement in VO2 max

thermal conductivity of water is about __ times greater than air

25

Having a high VO2 max would be a primary factor for success in performances lasting

3-20 minutes

high vapor pressure in the air

30 C and 75% relative humidity

Blood buffers would most likely improve performances lasting

30-180 seconds

Following a single bout of resistance exercise training, muscle protein synthesis can remain elevated above sedentary levels for as much as ______ in both trained and untrained individuals

35-50 hours

Heritability (i.e., genetics) determines approximately _____% of VO2 max variability in sedentary adults

50

High responders to endurance exercise training (i.e., individuals that achieve large increases in VO2 max) can achieve up to ______% improvement in VO2 max following a prolonged and intense training program

50

Depending upon body composition, water typically comprises ____ percent of body mass

50-60

Evaporation of one liter of sweat would result in the loss of ________ kcal of heat.

580

At three minutes of all-out high-intensity exercise, __________ of the ATP is derived from aerobic sources

60%

heat acclimatization occurs generally within

7-14 days

Compared to fat, lean body tissues contain significantly more water. The estimated percent of water in lean tissue is

75%

acidosis can occur due to

?

primary drive to increase ventilation during exercise is due to

?

Which of the following factors do not contribute to the endurance exercise training-induced improvement in VO2 max?

?increased maximal heart rate

Which of the following factors DO NOT contribute to the decline in VO2 observed during 84 days of detraining?

A decrease in maximal heart rate

What is the currently most used technique to screen for overweight and obesity?

BMI

technique of measuring body composition has the lowest error and provides an estimate of body composition that is within 0-1.8% of the "true value"

Dual Energy X-ray absorptiometry (DEXA)

In short-term performances (10-180 seconds) which is the primary cause of muscle fatigue?

H+ accumulation

homeotherms

Humans and other animals that maintain a rather constant body core temperature

exercise-induced hypoxemia that occurs in elite endurance athletes during heavy exercise is likely due to

a diffusion limitation secondary to a rapid RBC transit time

best protection against heat stroke and heat exhaustion

acclimatization

contraction of the rectus abdominis muscles would result in

active expiration

The method of body composition assessment that measures body volume similar to underwater weighing, but in the air (as opposed to underwater) is

air displacement plethysmography

interferes with cross-bridge "cycling" during exercise

an accumulation of H+

fatigue

an inability to maintain power output during repeated contractions.

a decline in arterial PO2 to 70 mm Hg or below would likely result in

an increase in alveolar ventilation

Resistance training results in an increase in the rate of contractile protein synthesis which is matched by ____

an increase in the synthesis of collagen in tendons and ligaments

carbon dioxide is transported in arterial blood principally as

bicarbonate

extracellular buffers contribute the most to the cell's buffering capacity

bicarbonate

breathing carbon monoxide can decrease VO2 max by

binding to hemoglobin to displace oxygen

The most rapid and effective method of reducing body temperature in those with high body temperature is

cold water immersion

One would expect that individual exposure to air pollution is increased during outdoor exercise because the dose of exposure is proportional to

concentration of particulate in the air and the ventilatory rate

transfer of heat from the body into molecules of cooler objects in contact with its surface is called

conduction

optimum body fatness for male athletes is

dependent on the sport and the individual

Which of the following durations of exercise would environmental factors play the largest role in determining performance?

events lasting 1-4 hours

small increases in arterial PCO2 have a ___ effect on ventilation compared to small decreases in PO2

greater

essential factors in the successful completion of an ultra-endurance event

having trained the body to markedly shift to fat oxidation to fuel the work performed during the ultra-endurance competition

physiological factor that would be beneficial to a mountain climber during high altitude climbing

higher PO2 in the blood

A single bout of resistance exercise training results in an increase in skeletal muscle protein synthesis. This exercise-induced increase in muscle protein synthesis can occur within _____ following the exercise session

hours

Following an acute bout of endurance exercise training, the increase in mitochondrial biogenesis occurs within _____ following the completion of the exercise session

hours

metabolic acidosis can result from the overproduction of ketoacids which can occur

in uncontrolled diabetes

hyperplasia

increase in the total number of muscle fibers

Exercise in the heat is associated with accelerated fatigue due to

increased free radical production in the active skeletal muscles

Endurance training has been shown to reduce the oxygen deficit in subjects performing a bout of submaximal exercise. This is likely due to

increases in the number of mitochondria and capillaries

Sodium bicarbonate has been ingested by athletes before competition in an effort to improve performance by

increasing blood buffering capacity

most of the O2 contained in the blood

is bound to hemoglobin as oxyhemoglobin

the most common and strongest acid produced in skeletal muscle during heavy exercise

lactic acid

Carbohydrate supplementation during exercise is most important in performances lasting

longer than 60 minutes

partial pressure of inspired O2 (PO2) decreases with increasing altitude because of the

low barometric pressure

Compared to competition at sea level, distance-running performances are generally not as good when conducted at high altitude due to

lower PO2 in the inspired air

major factor causing a decrease in VO2 max at moderate altitudes (~4000 m) is

lower oxygen extraction by muscle

A major regulator of protein synthesis and muscle size is __

mTOR

body density is equal to

mass divided by volume

ventilation

mechanical process of moving air in and out of the lungs

A healthy percent body fat for young adults (i.e., 18-44 years) is

men: 8-22%; women: 20-35%

Following an acute bout of endurance exercise training, the rise in the activity of calcinuneurin, calmodulin kinase, and AMP kinases occurs within _____ following the exercise session

minutes

Endurance exercise training results in an increase in mitochondria volume within skeletal muscle fibers. The process of synthesizing mitochondria in cells is called ______

mitochondrial biogenesis

acids

molecules that release H+

An increase in PCO2 in the blood results in the formation of bicarbonate in the red blood cell. Because bicarbonate carries a negative charge (anion), the removal of negatively charged molecule from the red blood cell is required to prevent an electrochemical imbalance across the cell membrane. This problem is avoided by

movement of chloride molecules into the RBC

The phenomenon that previous strength training accelerates the re-acquisition of both muscular strength and hypertrophy is commonly referred to as

muscle memory

A male with a body mass index of 29 kg/m2 would be classified as

overweight

pollutant generated by the reaction of UV light and emissions from internal combustion engines

ozone

In examining the mechanisms for exercise-induced fatigue, the vast majority of the evidence points to the

periphery

It is established that resistance exercise training promotes an increase in muscle protein synthesis by activating the mechanistic target of rapamycin (mTOR) which results in increased protein synthesis. Recent evidence suggests that two signaling molecules interact to directly activate mTOR. These molecules are:

phosphatidic acid and Ras homologue enriched brain (Rheb)

body's thermostat is located in the

prep-tic-anterior hypothalamus

potential mechanism of heat gain on a hot and sunny day outside

radiation

at rest, voluntary hyperventilation can result in __ due to __

respiratory alkalosis; decreased blood levels of carbon dioxide

compared to exercise in a cool environment, prolonged exercise in the heat

results in a more rapid onset of muscular fatigue

Aging is associated with a decline in strength, with most of the decline occurring after age 50. The loss of strength is due, in part, to a loss of muscle mass; this age-related loss of muscle mass is termed

sarcopenia

Studies suggest that elevating the levels of _____________ in the brain can contribute to "central" fatigue during prolonged endurance events

serotonin (5-hydroxytryptamine)

Endurance training results in increased mitochondrial and capillary density in muscle but has no effect on muscle glycolytic capacity. This is an example of what training principle?

specificity

Several hormones have the potential to increase muscle protein synthesis. These include:

testosterone, insulin-like growth factor-1 (IGF-1), and growth hormone

Growing evidence reveals that, independent of resistance exercise, ____________ can activate mTOR and promote small increases in muscle protein synthesis

the amino acid leucine

Following several weeks of endurance exercise training, the capacity to transport glucose into skeletal muscle fibers is increased. Which of the following training-induced changes contribute to this training effect?

the increase in the number of GLUT4 glucose transporters

Research indicates that following a series of voluntary contractions to produce skeletal muscle fatigue, electrical stimulation of the "fatigued" muscle group results in an increase in the maximal voluntary force production. This experiment suggests that:

the upper limit of voluntary strength is psychologically set and that the central nervous system can limit performance.

The heart rate and ventilatory responses to constant load submaximal exercise are lower (i.e., lower heart rate and lower minute ventilation) following an endurance training program. This training-induced adaptation is primarily due to changes in the

trained skeletal muscles

Resistance training increases the specific force production of __

type I muscle fibers

When the intensity of exercise exceeds 75% of VO2 max, which of the following fibers are likely brought into play

type IIx

evaporation of sweat is dependent upon environmental

vapor pressure

Research reveals that resistance training induced muscle hypertrophy is associated with an increase in myonuclei. The source of these additional myonuclei is ___

via satellite cell activation

To quantify the overall heat stress associated with any environment, the ______ guide was developed

wet bulb temperature