study set

a pH < ___ will stop glycolysis

6.5

this kind of diet increases muscle glycogen stores and aerobic time to exhaustion

High-carbohydrate diet

true/false: only aerobic athletes can benefit from improving their cardiorespiratory endurance

false

during endurance exercise, fatigue correlates best with

low glycogen stores

during maximal, all out exercise lasting 20-30s fatigue correlates best with

low pH

which of the following is not true regarding lactic acid

it is a byproduct of oxidative metabolism

____ is most often caused by an accumulation of fluid or H+

acute muscle soreness

which of these is not a cause of strength loss with DOMS?

long term accumulation of lactic acid in muscle tissue

the neuromuscular system is _____

one of the most responsive systems to train

when motor units contract more synchronously

muscles increase the rate of force development

____ training is critical in developing fiber hypertrophy

eccentric

the most common fiber type alteration with heavy resistance training is

more type IIa, less type IIx

strength losses after immobilization are greatest during the ____

first week

the recommended amount of protein to consume following RT is _____g

20-25g

transient hypertrophy is primarily stimulated by

edema

which sarcomere structure reveals the most information about the intensity of eccentric exercise?

Z-disc

immobilization primarily affects

type I fibers

in untrained individuals, motor units are recruited asynchronously

true

the primary source of heat loss during exercise in heat is

evaporation

when an athlete is exercising in hot and humid weather

core temperature increases faster

heat acclimation is best achieved through

9-14 days of low to moderate intensity exercise in the heat for >1hr a day

heat cramps must be treated with

rapid sodium replenishment

during exercise in the cold, muscle

contractile forces decrease

frostbite should be rewarmed

preferably, in a hospital

the main cause of exercise induced asthma is

cold air+dry air

___is the long term, gradual adaption of the body to environmental stressors over a period of months/years

acclimatization (permanent)

____ refers to the transfer of heat by the movement of gas or liquid across a surface

convection

the transfer of heat between two solid surfaces is known as ____

conduction

when the body gains or loses heat through infrared rays, this is called____

radiation

the term used to describe heat loss that occurs as a liquid turns into a gas is called

evaporation

____ is the progressive decline in core temperature during cold exposure

Hypothermia

for thermoregulatory purposes, the body can be divided into 2 major components: the superficial shell and the deep core

true

sweating and skin vasodilation are the body’s only physiological heat loss mechanism

true

during the early phases of altitude exposure, muscle O2 exchange is diminished due to….

lower arterial PO2

during acute altitude exposure, maximal intensity aerobic exercise is characterized by…

diminished maximal cardiac output

VO2max starts to decline at approximately

1,500 meters elevation

if you’re competing at altitude, how early should you arrive at your performance destination in order to acclimate?

2-3 weeks

which of these conditions has the highest chance of happening at altitude?

sunburn

the partial pressure of O2 is proportional to

barometric pressure

dehydration can happen quickly at altitude as a result of all of the following except

high radiation

during acute altitude exposure, cardiac output increases due to

increased heart rate

the major factor that drives the acute altitude associated decrease in VO2max is

inadequate alveolar PO2

increased pulmonary ventilation during acute exposure to altitude is stimulated by

chemoreceptors

Pb x .2093 = PO2

true. This equation calculates the partial pressure of oxygen (PO2) in the atmosphere, where Pb is the barometric pressure and 0.2093 represents the fractional concentration of oxygen in dry air.

during exercise, protein synthesis

decreases

after exercise, protein synthesis

increases

when protein breakdown exceeds protein synthesis, which of the following occurs?

atrophy

what prevents a muscle from contracting with excessive force that could damage the tendons and bones?

autogenic inhibition

satellite cells are

myogenic stem cells involved in muscle regeneration

which of the following is a chronic adaption to altitude exposure?

increased EPO production

name and explain at least 3 neural changes that improve strength before hypertrophy occurs labeled

1. Increased motor unit recruitment: More motor units are activated during a muscle contraction, enhancing overall strength.

2. Improved synaptic efficiency: Enhanced communication between neurons leads to quicker activation of muscles.

3. Greater firing frequency: Increased rate at which motor neurons fire improves the force and speed of muscle contractions.

know how to calculate sweat rate and total daily fluid needs (remember 3.7L for men and 2.5L for women)

Sweat rate can be calculated by measuring body weight loss during exercise, adjusting for fluid intake, and time spent exercising. Total daily fluid needs are estimated at 3.7 liters for men and 2.5 liters for women, considering activity level and environmental conditions.

be able to explain why holding your breath while ascending from a dive is dangerous

Holding your breath during ascent can cause air bubbles to expand rapidly, leading to lung over-expansion injuries or decompression sickness. As pressure decreases, trapped air in the lungs can rupture tissue or cause severe pain, requiring immediate medical attention.

be able to explain why a left shift in the O2-Hb dissociation curve is beneficial at altitude and what is contributing to this shift labeled

A left shift in the O2-Hb dissociation curve indicates increased affinity of hemoglobin for oxygen, which is beneficial at altitude as it enhances oxygen uptake in the lungs. This shift is primarily contributed by decreased temperature, increased pH (Bohr effect), and lower levels of carbon dioxide, allowing the body to more efficiently utilize available oxygen in low-pressure environments.

What is muscle hypertrophy, and how does it relate to protein synthesis and breakdown?

Muscle hypertrophy is an increase in muscle size and cross-sectional area, occurring when muscle protein synthesis exceeds muscle protein breakdown.

What is a reasonable expectation for percentage strength gains after a 6-month resistance training program in untrained individuals, and what are these increases attributed to?

Strength gains typically range from 25-100% or more. These increases are initially (first 8-10 weeks) primarily attributed to neural adaptations, and subsequently to muscle hypertrophy.

How does motor unit recruitment change with resistance exercise training?

Resistance exercise training leads to increased motor unit recruitment, including activating more high-threshold motor units, improving rate coding (faster firing frequency), and enhancing motor unit synchronization.

How does autogenic inhibition change with resistance exercise training?

Resistance exercise training reduces autogenic inhibition, allowing muscles to generate greater force by overriding the inhibitory signals from Golgi tendon organs.

What is chronic hypertrophy and what is its underlying reason?

Chronic hypertrophy is the long-term increase in muscle size due to structural changes within the muscle fibers, primarily resulting from increased synthesis of myofibrillar proteins (actin and myosin), sarcoplasmic reticulum, and connective tissue.

What specific changes occur within a muscle fiber during muscle hypertrophy?

During muscle hypertrophy, there is an increase in the number and size of myofibrils, an increase in actin and myosin protein content, and an increase in the volume of sarcoplasm and associated connective tissue, leading to a larger muscle fiber cross-sectional area.

What is the critical factor for short-term increases in muscle strength, and what is it for long-term increases?

The critical factor for short-term increases in muscle strength (initial 8-10 weeks) is neural adaptations. The critical factor for long-term increases in muscle strength is muscle hypertrophy.

How are different muscle fiber types affected during muscle atrophy, particularly with immobilization?

During muscle atrophy, protein breakdown exceeds protein synthesis, leading to a decrease in muscle mass. Type I (slow-twitch) muscle fibers are often more significantly affected and show greater atrophy, especially during periods of immobilization.

What are the key biochemical and cellular changes that occur with resistance training?

1. Increased muscle protein synthesis. 2. Activation and proliferation of satellite cells. 3. Increased myofibrillar proteins (actin, myosin). 4. Potential shifts in fiber type (e.g., Type IIx to Type IIa). 5. Increased muscle glycogen stores. 6. Enhanced antioxidant enzyme activity.

What are the capillary and cardiovascular effects of resistance training?

Capillary Effects: Capillary density (capillaries per fiber) may remain unchanged or slightly decrease, but overall capillary per unit area typically remains stable as muscle size increases. Cardiovascular Effects: Modest increases in left ventricular wall thickness and mass, slight decreases in resting heart rate, and no significant change or slight increase in stroke volume and cardiac output. Acute exercise causes substantial increases in blood pressure.

How does protein and amino acid supplementation affect protein synthesis, and does timing matter?

Protein and amino acid supplementation, particularly when combined with resistance exercise, enhances muscle protein synthesis by providing necessary amino acid building blocks. While total daily protein intake is most critical, consuming protein within a few hours before or after exercise, and potentially before sleep, can optimize muscle adaptations.

What are the four primary modes of heat transfer, and which is most prominent at rest versus during exercise?

The four modes are conduction, convection, radiation, and evaporation. At rest, radiation and convection are the primary modes of heat loss (at normal room temperature). During exercise, evaporation becomes the primary mechanism for heat loss.

Explain the sweating mechanism for heat loss and how high ambient humidity affects its efficiency.

Sweating involves the secretion of water from sweat glands onto the skin surface. As this water evaporates, it carries heat away from the body, thus cooling it. High ambient humidity reduces the vapor pressure gradient between the skin and the air, impairing the rate of sweat evaporation and thereby reducing the effectiveness of cooling.

Describe the process of thermoregulation at rest, including the body's responses to hyperthermia and hypothermia.

Thermoregulation is the body's ability to maintain a stable internal core temperature. At rest, if core temperature rises (hyperthermia), the body responds by increasing blood flow to the skin (vasodilation) and initiating sweating to enhance heat loss. If core temperature falls (hypothermia), the body responds by shivering (which generates heat) and reducing blood flow to the skin (vasoconstriction) to conserve heat.

How do environmental load and clothing choices impact thermoregulation during physical activity?

Environmental load (e.g., high temperature, humidity, solar radiation) increases the challenge on the body's thermoregulatory system, demanding greater heat loss. Appropriate clothing (light-colored, loose-fitting, moisture-wicking in heat; layered, insulating, wind/waterproof in cold) helps manage heat exchange, either facilitating evaporation and heat dissipation or preventing heat loss.

Outline the key physiological responses when exercising in hot environments compared to cold environments.

In hot environments, responses include increased heart rate, increased skin blood flow, increased sweating, and faster core temperature rise. In cold environments, responses include peripheral vasoconstriction, shivering, reduced muscle contractile force, and increased metabolic heat production.

What are the general health risks associated with exercising in hot and cold environments?

In hot environments, risks include heat cramps, heat exhaustion, and heat stroke. In cold environments, risks include hypothermia, frostbite, and exercise-induced asthma.

What are the physiological benefits and mechanisms of heat acclimation?

Heat acclimation improves the body's ability to tolerate exercise in the heat. It involves physiological adaptations such as increased plasma volume, earlier onset and higher rate of sweating, reduced sodium loss in sweat, reduced heart rate for a given workload, and a lower core temperature.

What are the main environmental differences between sea level and altitude?

At altitude, barometric pressure is lower, leading to a decreased partial pressure of oxygen (PO_2), cooler temperatures, and lower humidity. UV radiation is also typically higher.

How does barometric pressure impact the PO_2 in the atmosphere and in the tissues?

As barometric pressure decreases with increasing altitude, the partial pressure of oxygen (PO2) in the atmosphere decreases proportionally. This lower atmospheric PO2 directly leads to a reduced PO_2 in the alveoli and arterial blood, subsequently impairing oxygen diffusion into the tissues.

Describe the acute responses to ventilation, diffusion, plasma volume, SV, Q, a-vO2 difference, and RBC count at altitude vs sea level, and how these change after a few days at altitude.

1. Acute (vs. sea level):
   • Ventilation: Increases
   • Diffusion: Diminished due to lower PO_2 gradient
   • Plasma Volume: Decreases
   • Stroke Volume (SV): Decreases
   • Cardiac Output (Q): Increases via increased HR (initially to compensate)
   • a-vO2 difference: Decreases (less O2 extraction)
   • RBC count: Unchanged
2. After a few days:
   • Ventilation: Remains elevated but might slightly decrease from initial acute peak
   • Plasma Volume: Stabilizes at a lower level
   • Cardiac Output (Q): Decreases towards sea level values as RBC count begins to rise
   • a-vO2 difference: May start to increase slightly as acclimatization begins
   • RBC count: Erythropoietin (EPO) production increases leading to gradual increase in RBC count

Describe the acute change to the O2-Hb Dissociation Curve at altitude and its effect on O_2 at alveoli and muscle.

Acutely, the O2-Hb dissociation curve shifts to the right at altitude due to increased 2,3-DPG, which helps facilitate oxygen unloading at the tissues despite lower PO_2. However, this right shift also slightly impairs oxygen loading in the alveoli.

After a few days at altitude, how does a-vO2 difference change, and how does this affect cardiac output (Q)?

After a few days at altitude, the a-vO2 difference may slowly increase as the body adapts to extract more oxygen from the blood. This allows cardiac output (Q) to decrease from its initial acute increase, moving closer to sea-level values but at a higher red blood cell concentration.

What is Erythropoietin (EPO), how is it stimulated, and what is its effect on performance potential?

EPO is a hormone produced primarily by the kidneys that stimulates red blood cell production in the bone marrow. It is stimulated by low arterial oxygen pressure (PO_2) at altitude. Increased RBC count enhances oxygen-carrying capacity, improving aerobic performance potential.

How does plasma volume change after chronic exposure to altitude, and what are the implications for cardiac output (Q) and VO_{2max}?

After chronic exposure to altitude, plasma volume decreases and stabilizes at a lower level, which concentrates red blood cells. This contributes to a reduced maximal cardiac output (Q) at altitude, but the increased oxygen-carrying capacity from higher RBC count helps maintain or improve VO_{2max} efficiency by increasing the a-vO2 difference.

How is VO_{2max} affected at altitudes?

VO_{2max} progressively declines with increasing altitude above approximately 1,500 meters due to the reduced partial pressure of oxygen in the atmosphere, which limits oxygen loading in the lungs and delivery to the working muscles.

How is anaerobic performance affected at altitude, and why?

Anaerobic performance is generally maintained or can even be slightly improved at altitude because it relies less on oxygen delivery. The lower air density at altitude can also reduce air resistance for sprinters and jumpers, potentially offering a small advantage.

Explain why the "live high, train low" strategy is considered optimal for aerobic training at altitude.

The "live high, train low" strategy maximizes the benefits of altitude acclimation (increased EPO, RBC count, and oxygen-carrying capacity) by living at altitude, while allowing athletes to maintain high training intensities and workloads at lower altitudes, where sufficient oxygen is available to train maximally and avoid detraining.

How does barometric pressure change when going underwater?

When going underwater, the inspired air pressure (and thus barometric pressure experienced by the body) increases significantly, by approximately 1 atmosphere (atm) for every 10 meters (33 feet) of descent.

How does diving alter overall cardiovascular and lung function?

Diving triggers the mammalian dive reflex, which includes bradycardia (decreased heart rate), peripheral vasoconstriction (reduced blood flow to limbs), and blood shift (fluid shifting from limbs to thoracic cavity) to conserve oxygen. Lung function is altered by increased external pressure, compressing lung volumes and increasing gas density.

How does voluntary hyperventilation affect breath-hold ability, and why is it potentially dangerous?

Voluntary hyperventilation before breath-holding reduces the body's carbon dioxide (CO2) levels. Since CO2 is the primary stimulus for breathing, this allows for a longer breath-hold. However, it is dangerous because it can lead to unconsciousness (shallow water blackout) before the urge to breathe becomes strong enough, due to critically low oxygen levels in the blood.