Exercise Physiology Exam #2

How does dehydration affect exercise performance, especially on heart rate, blood flow distribution, and body temperature?

Dehydration increases heart rate and body temperature and decreases blood flow.

What are the physical results of excessive weight loss?

Dehydration, chronic fatigue, eating disorders, menstrual dysfunction, and bone mineral disorders are all results of unhealthy, excessive weight loss.

Which fuel substrate do children rely on more during aerobic exercise?

Fat

What is hypoxia and hypoxemia?

Hypoxia — a decreased availability of oxygen to the tissues Hypoxemia — a decreased oxygen content or concentration within the blood

Why is oxygen supplementation not used very often during exercise?

It can be inconvenient because the athlete would have to exercise with a mask on their mouth and have an O2 tank near them at all times.

Why does aerobic training in children lead to improved running performances?

It improves the running economy effort.

What is ketoacidosis and what special population may be affected by it with exercise?

Ketoacidosis is a serious complication of DIABETES that occurs when the body produces high levels of ketones — the use of fat as fuel results in the ketone byproduct.

Stroke volume in women is _______ than in men due to ______________________.

Less The fact that women have smaller-sized hearts compared to men.

What is sweat primarily composed of once acclimatized?

Less amounts of NaCl.

The best way to lose weight in preparation for an upcoming competition season is to do what?

Lose 0.5-1 kg per week by kilocalorie restriction and exercise

____________ glycemic index foods are best before exercise, while ____________ glycemic index foods are best immediately after exercise.

Low High

Although exceptions can and do exist, generally women have ___________ VO2max compared to men.

Lower

During maximal exercise, cardiac output in women is _________ than in men.

Lower

What is VO2max - define it and what determines its limits?

Maximal capacity for aerobic re-synthesis of ATP. VO2 max = HR max x SV max s (a-v)O2max (Fick equation). Cardiovascular system, respiration, metabolism could determine its limits.

What is the ideal CHO concentration in sports drinks?

Most sport drinks have 6-8g of CHO per 100 mL of fluid.

What is the primary metabolic fuel source during exercise in the cold?

Muscle glycogen

Why does stroke volume increase from childhood through adolescence to adulthood?

Stroke volume increases because the heart size and blood volume increases as the body size increases.

The initial decrease (first 12 days) in VO2 max in highly trained individuals who stop training is due to a decrease in what physiological component and why?

Stroke volume would decrease. This is due to the patient having an increased heart rate and breathing rate with a rapid loss of plasma volume.

What happens to oxygen at altitude?

The air is less dense and there are fewer O2 molecules per liter of air.

Endurance training causes large changes in the biomechanical/structural characteristics of the working muscles. Name some changes that occur.

increase mitochondrial number; increase capillary density; Type 2x to 2A to 1; More oxidative capacity; Increased cross sectional area of muscle fibers type 1; Fats are mobilized (spars glucose in muscle)

Four to six months of aerobic training in older populations can restore VO2max to values seen ________ years earlier.

20

VO2max decreases in normally active older individuals by ______% per decade after age 20-25.

5-6

Which of the bioenergetic systems is relatively unchanged from childhood to adulthood?

ATP-PCr

What athletic events are affected the most by altitude: anaerobic v aerobic and why?

Activities of long duration that place demands on oxygen transport and uptake by the tissues are those that are most severely affected by hypoxic conditions at altitude. The thinner air at altitude provides aerodynamic resistance to athlete's movements.

Altitude and performance - what changes occur both aerobically and anaerobically when transitioning from sea level to altitude and altitude to sea level during exercise?

Activities of long duration that place demands on oxygen transport and uptake by tissues are those that are most severely affected by hypoxic conditions at altitude. Aerobic exercise performance is most affected by hypoxic conditions at altitude (>2min). Anaerobic performance is unaffected (<2min) — ATP-PCr and anaerobic glycolytic metabolism, minimal O2 requirements. Thinner air = less resistance — improves running and swimming times (up to 800m) as well as improved jump distances.

What are acute mountain (altitude) sickness, HACE, HAPE?

Acute mountain sickness — illness characterized by H/A, nausea, vomiting, dyspnea, and insomnia. Begins 6-96 hours after reaching high altitude, can last several days. HACE (high-altitude cerebral edema) — condition of unknown cause in which fluid accumulates in the cranial cavity at altitude, characterized by mental confusion that can progress to coma and death HAPE (high-altitude pulmonary edema) — a condition of unknown cause in which fluid accumulates in the lungs at altitude, interfering with ventilation, resulting in shortness of breath and fatigue, impaired blood oxygenation, mental confusion, and LOC

The combination of alcohol plus energy drinks yields what type of a response?

Alcohol is a depressant and energy drinks are stimulants, so when the two combine together it can cause an ergolytic response.

Creatine supplementation would be most helpful for which athlete?

Athletes involved in a team sport, or other activities that involve repeated, high-intensity movement.

Which family of vitamins is critical for cellular metabolic processes?

B-complex vitamins are critical for cellular metabolic functions. Thiamin (B1) is needed for conversion of pyruvic acid to acetyl coenzyme. Riboflavin (B2) acts as a hydrogen acceptor during oxidation. Niacin (B3) is a coenzyme in glycolysis. B12 has role in amino acid metabolism and is needed for the production of RBCs.

What is an advantage for women for thermoregulation in the cold?

Because women have more fat, this makes their bodies better insulated, leading to a lower chance of getting a cold illness compared to men.

Why is bicarbonate loading considered an ergogenic aid?

Bicarbonate ingestion of 300 mg/kg of body mass can enhance performance of an all-out maximal anaerobic activities of 1-7 minute duration.

Which form of body composition assessment relies on tissue conductivity?

Bioelectric impedance

What cardiovascular variables are higher during a single bout of submaximal exercise in children (compared to adults)?

Blood flow to active muscles and heart rate.

The most abundant mineral in the body is what?

Calcium

How is cardiac output affected by altitude?

Cardiac output increases — short term adaptation (6-10 days); delivers more O2 to tissue per minute. After a few days the muscles extract more O2, therefore reducing the demand for cardiac output.

What is cardiovascular drift and why might this be a problem with prolonged exercise?

Cardiovascular drift is an increase in HR during exercise to compensate for a decrease in SV — compensation helps maintain a constant cardiac output.

Exercise in the heat - how body systems are affected

Cardiovascular — skin arterioles VD to increase heat loss, requires increase blood flow; POAH triggers SNS, cardiac output increases further via HR/contractility, increase VC to nonessential tissues; blood volume decreases (sweat), SV can't (blood pooling) so HR further to compensate (cardiovascular drift)

VO2max improves with aerobic training due to __________ adaptations in young exercisers and _______________ adaptations in older exercisers.

Central Peripheral

What effects does exercise training have on thermoregulation in the heat in older individuals?

Core temperature is higher in older athletes compared to younger athletes — leads to higher risks of death due to hyperthermia.

Which commonly used method of body composition measurement is the most accurate?

Densitometry has been the long used method of choice for measuring body composition. This method involves measuring the density of the athlete by placing them in water on a scale and then using the formula Dbody = Mbody/Vbody.

Due to caffeine's effects on fluid balance in the body, it could also be called what?

Diuretic

How does endurance training alter fat metabolism?

Endurance training mobilizes free fatty acids more easily.

Which heat loss method is most affected by age?

Evaporation

What is the fuel source used at rest at altitude and why?

Glucose — needed to break down fat.

An amenorrheic athlete would most likely be found on which teams?

Gymnastics and cross-country — any sport that requires a smaller-framed body.

Effect on VO2max and cardiac output

Heart rate decreases and cardiac output increases.

What happens with heat and cold acclimatization? What are the physiologic purposes of acclimatizing to each?

Heat — skin arteriole vasodilation to increase heat loss; requires an increase in blood flow compared to exercise in the cold; POAH triggers the SNS which then increases cardiac output and vasoconstriction in nonessential tissues; blood volume decreases and the SV cannot increase, so HR increases to compensate. Cold — muscle function decreases; fiber recruitment is altered, shortening velocity and power decreases; as fatigue increases the metabolic heat production decreases; energy reserve depletion with endurance exercise is a potential for hypothermia.

How is body temperature regulated during exercise? what happens in both cool and hot/humid environments?

If the body's heat production exceeds its heat loss, as it often does during moderate-to-heavy aerobic activity, the body stores excess heat, and internal temperature increases. Hot environment — water vapor pressure of the air plays a major role in evaporative heat loss. High humidity limits sweat evaporation and heat loss, low humidity is an ideal opportunity for sweat evaporation and heat loss. Cold environment — body loses heat 4x faster in water than it does in air of the same temperature. Exercise in water increases the metabolic rate and offsets some of the heat loss.

What are the proposed benefits of taking amphetamines?

Improve alertness, concentration, reaction time, and perceived energy levels.

Why is the (a-v)O2 difference during a single bout of exercise higher in children than in adults?

In children (a-v)O2 is higher due to the decreased stroke volume.

What best describes the effects of amphetamines on the body?

Increase alertness, increase concentration, elevate mood, decrease fatigue, decrease reaction time (faster response), enhance catecholamine release, increased free fatty acid mobilization, increased use of muscle triglycerides.

What are some of the most important adaptations that the body makes in response to endurance training which allows for an increase in both VO2max and performance?

Increase capillary density

Women have greater fat deposition on their hips and thighs due to local increased activity of what enzyme?

Increase in lipoprotein lipase activity.

How is VO2max important to endurance performance and why does a person with the highest VO2max not always win a race?

Increased VO2max = increased aerobic (endurance) capabilities. VO2 has nothing to do with speed, just distance.

What precaution should older athletes take when exercising in the cold?

Older athletes should wear the appropriate clothing for the temperature outside in order to stay warm during exercise — prevent cold-related illnesses.

The presence of irregular or inconsistent menstrual cycles is called what?

Oligomenorrhea

What changes occur in the plasma volume and red blood cells with increasing levels of exercise and prolonged exercise in the heat?

Plasma levels increase (temporary, back to normal in 10 days) due to increase in oncotic pressure. Increased skin blood flow. Decreased heart rate and increased cardiac output. Blood volume decreases (sweat), SV cant increase (blood pooling), heart rate increases further to compensate (cardiovascular drift). Skin arterioles VD to increase heat loss, requires increase blood flow compared to exercise in the cold.

Explain how a 12-week aerobic training program will affect the following factors — preload, afterload, heart rate, and anteriovenous oxygen difference.

Preload increases, allowing for a well-trained heart for an increased preload within the left ventricle. Afterload decreases, allowing less resistance to push out against due to a well-trained heart. Heart rate decreases due to increased SV, allows for less HR for the same cardiac output. AvO2 increases — increasing the capillary beds will allow for more efficient extraction of O2 and the removal of CO2.

What are the 2 primary factors, not including myocardial contractility, that increase stroke volume?

Preload — increased venous return to the heart Afterload — the arterial reistance to blood that the heart must pump against to eject blood

The most widely applied field technique for assessing body composition is what?

Skin-fold fat thickness is the most commonly used field technique.

When an athlete is training very hard, what should their protein intake be?

Protein and specific amino acid requirements are higher in those who train compared to normally active people. Strength-training people need 2.1x the RDA — 1.6-1.7g of protein per kg of body weight per day. Athletes who are in endurance training need 1.2-1.4g of protein per kg of body weight per day.

How does the body adapt to altitude?

Pulmonary — increase in pulmonary ventilation at rest and during exercise. Resting ventilation rates increase about 40% higher than sea level; plateaus at about 50% higher, but over a longer time frame. Muscle — capillary density in the muscles increases, allowing more blood and oxygen to be transported to muscle fibers. Blood — RBCs increase causing hematocrit levels to go up. Plasma volume will increase over several weeks, maximal cardiac output increases as RBC levels increase. Cardiovascular — decrease in VO2max with initial exposure; does not improve much over time and will most likely not go back to how it was at sea level.

What happens to RBCs at altitude?

RBC count increases at altitude due to the demands of the body to transport oxygen to surrounding tissues.

β-blockers can lead to what effects?

Reduction in maximum heart rate; increase in hand stability.

How does HR, SV, and CO respond to increasing rates of work? To endurance training? To detraining?

SV increases after training. Resting and submaximal HR decreases with training. Cardiac output — training creates little to no change at rest, submaximal exercise. Maximal cardiac output increases considerably due to increase stroke volume.

What are the two primary means of heat production and 4 means of heat loss?

Shivering — increases heat production by 5x Non-shivering thermogenesis — action of hormones (thyroxine and catecholamines) Conduction — transfer of heat from one solid material to another through direct molecular contact Convection — transferring of heat by the motion of a gas, or a liquid across the heated surface Radiation — heat is given off in the form of infrared rays, a type of electromagnetic wave. Evaporation —fluid evaporates and turns into a gaseous form, therefore losing heat.

β-blockers would be used to enhance performance for which sports?

Shooting sports, archery, billiards, or golf.

Which cardiovascular change is the primary cause of age-related decrements in VO2max?

There will be a decrease in the maximal HR.

Diuretics are usually taken by athletes for what purpose?

To help with weight control and dilute banned substances in urine samples.

If fat-free mass increases, what will happen to athletic performance?

When FFM increases, the athlete's performance can be impaired (depending on the sport). Increasing FFM is desirable for athletes who are involved in sports that require strength, power, and muscular endurance. Sports that require cardiovascular endurance (like a runner) will not see an increase in FFM as being desirable.

Why is there a potential for "detraining" when go from sea level to altitude?

When someone "lives and trains high", this leads to dehydration, low blood volume, and low muscle mass. So someone who is physically fit at sea level will have issues as they increase in altitude.

What happens to sweating mechanism with acclimatization?

Widespread sweating occurs earlier and is more dilute which prevents the loss of too much NA+.

What is true regarding thermoregulation in women?

Women carry more fat on them (due to childbearing) so exercising in the heat makes them more prone to heat illness.