IPHY 4650 Lab Exam 2

What are they ways you can predict VO2 max? (what regression equations?)

1. Non-exercise equations: Age, Sex, BMI, PA-R (physical activity rating), PFA (perceived functional ability)

2. Sub-max heart rate equation: extrapolation using age predicted HR-max. Queens College Step Test

What is the importance of estimating VO2 max?

Helpful for making exercise prescriptions. It can be difficult to get direct measure of VO2 (expensive equipment, trained staff, time constraints, motivation, etc.)

What assumptions are made from estimating VO2 max from submax HR ?

1. Linearity of HR-VO2 (from 120bpm-HRmax)

2. Max Heart rate can be estimated based on age

3. Assumed exercise economy (influenced by: cadence, test modality, and between subject differences in economy)

What is the % error when estimating VO2 max? (standard error of estimate)

Standard error of estimate for VO2 max when estimating from HR in submaximal test is 5mlkg^-1min^-1. If the predicted VO2 max is 40 mlkg^-1min^-1 there is a 68% likelihood that that actual VO2 max is between 35-45mlkg^-1min^-1.

What are the two equations we use to estimate exercise intensity?

1. VO2R= VO2 max- VO2 rest

2. HRR= HR max- HR rest

Why can measurements of VO2 max be contradicted or impractical?

1. motivation varies

2. trained staff necessary

3. expensive equipment

4. time constraints

5. medical considerations

How would relative intensity of submaximal exercise be affected if max heart rate was overestimated?

Your relative intensity would be higher if max heart rate was overestimated. This is due to the fact that heart rate and power output have a positive linear relationship. Your relative intensity would be at a higher % of individuals true maximum HR.

How do you know when an individual has reached their steady state?

An individual has reached their steady state when their heart rate does not change more than 6 beats per minute for 2 consecutive minutes.

What is the ideal linear range between heart rate and exercise intensity when graphing the extrapolation of HR during submax exercise?

heart rate must be greater than 120 bpm but less than 85% HRmax

Will a trained individual have a lower or higher heart rate at given VO2?

A trained individual will have a lower heart rate at a given VO2. They will achieve a higher oxygen consumption before reaching their maximal heart rate.

True or false: Subject with a greater aerobic capacity will have a lower heart rate following short exercise bouts.

True (for those of the same gender)

Based on ACSM Position Stand, which of the following would be expected to result in health benefits?

- meeting ACSM's exercise guidelines for physical activity

- Reducing time spent in sedentary pursuits

- Breaking up prolonged periods of sedentary behavior

What influences the linearity of the HR-VO2 relationship?

Emotion, hydration, oxygen drift, temperature, diet, etc.

What can help make improvements in cardiorespiratory fitness?

Intensity of exercise and duration can help improve cardiorespiratory fitness.

What does the American College of Sports Medicine prescribe for developing and maintaining cardiorespiratory fitness?

Exercise 3-5 days per week for 20-60 minutes at 50% VO2 reserve

What is VO2R? How do you calculate VO2R?

VO2 reserve is a term that describes the actual physiological range of oxygen consumption for an individual. VO2R (L/min)= exercise intenisty (%) x (VO2 max- VO2 rest) +VO2 max

How do you calculate HRR?

HRR (beats/min) = exercise intensity (%) x (HRmax-HRrest) + HR rest

Calculate age predicted HR max

HR max= 208 - (0.7*age)

What are METs equal to?

3.5 mlkg^-1min^-1

Is BMI an adequate measurement of disease risk ?

No, because BMI can not break down the actual composition of our body. Thus it is not adequate measurement of disease risk for some individuals

How can waist measurement be a valuable measurement?

Waist circumference is valuable to asses central obesity. Fat located in abdominal region also known as visceral fat is associated with greater health risk that peripheral fat and is independent risk factor when BMI is not markedly increased.

Why is beneficial to know you body composition?

determine how much body fat % you have, determine the amount of fat free mass, as well as determining your bone density.

How do you calculate BMI?

weight (kg) / height (m^2)

What is the difference between android and gynoid?

Android: upper body obesity, fat primarily in abdominal region and poses as a greater health risks

Gynoid: lower body obesity, fat is primarily in hips and thighs and poses as less of a health risk

How can waist circumference be utilized? Is it widely adopted?

Should be utilized for assessments of obesity and for monitoring the efficacy of weight-loss programs. Not widely adopted due to questions on standardization but the World Health Organization published recommendations for waist circumference in conjunction with BMI to asses health risk.

Is there a direct way to measure different components in the body?

There is NO DIRECT in vivo method to measuring components in body therefore any technique performed on individuals is either indirect or doubly indirect. Indirect methods are derived from direct methods involving cadavers while doubly indirect methods are derived from indirect methods.

What is the Siri equation?

Body Fat (%)= (495/body density) -450

We use the Siri equation to predict percent body fat, a generalizable equation (equation that is developed from diverse, heterogenous samples that account for age, sex, gender, race or ethnicity, and other characteristics.

What do skinfold measurements asses? What method is this indirect or doubly indirect?

They can asses percent body fat with standard error of estimate (SEE) of ~ 3.5%. Skinfold measurements are doubly indirect and it is based on hydrostatic weighing which is an indirect method that utilizes water displacement to estimate fat mass.

What assumptions are based on skinfold measurements?

1. subcutaneous fat is directly proportional to total fat

2. the skinfold sites selected are representative of total body subcutaneous fat

-However it is known that proportion of subcutaneous to total body fat varies with age, sex, race or ethnicity, and several other factors.

What accounts for the SEE to be ~3.5% for skinfold measurements?

Technician training, applicability of equations to the individual being tested, skinfold site measurement accuracy, and measurement technique.

How does BIA (bioelectrical impedance analysis) work and what does it measure?

BIA is a quick, inexpensive, and non invasive technique for measuring body composition.

It is based of the principle that electrical current flows at different rates through the body depending on composition. Body fat causes greater resistance (impedance) than fat free mass and slows the rate at which the current travels.

What is a DEXA scan and what does it measure?

DEXA (Dual Energy x-ray absorptiometry) utilizes X-rays to scan and quantify parameters of body composition.

DEXA puts body weight into three categories: lean soft tissue, fat soft tissue, and bone.

DEXA is an indirect measurement.

What is a T-score?

T-score compares your bone density to the average bone density of young healthy adults of the same sex.

What is a Z-score?

Z-score compares your bone density to the average bone density of someone your age, sex, and race/ethnicity.

List the types of bone density levels depending on the SD given.

Normal Level (BMD): BD is within 1 SD of mean

Low Bone Mass Level (BMD): BD is within 1-2.5 SD below mean

Osteoporosis Level (BMD): BD is 2.5 SD or more below mean

Severe Osteoporosis Level (BMD): BD is more than 2.5 SD below mean and there have been one or more osteoporotic fractures

Is there an accepted standard for body fat percentages? What is the recommended health standard for body fat percentage from the NHANES?

There are no accepted standards for percent body fat, and all methods of measurement are indirect and involve error.

NHANES recommends that body fat percentage ranges from 20-35% for women under 35 years old, and 8-22% for men under 35 years old.

Not all researches agree with this range!

Define accuracy, precision, and bias.

Accuracy represents how close a measured value is to the true value.

Precision: represents how close measured values are to each other

Bias: represents whether there are systemic differences between measured and true values.

What is the athlete triad?

The athlete triad is recognized as a syndrome of three interrelated conditions that include low energy availability (w/wo disordered eating), functional hypothalamic amenorrhea (females) or hypogonadotropic hypogonadism, and osteoporosis.

Understanding athlete triad more in terms of male athletes.

Syndrome of three interrelated conditions that include low energy availability (w/wo disordered eating), hypogonadotropic hypogonadism, and osteoporosis.

Male athletes participating in sports emphasizing leanness who present with bone stress injuries may also exhibit concurrent nutritional, endocrine, and/or bone health concerns like those of women with triad.

What is energy availability defined as?

EA (kcal/kg) = (dietary intake (kcal/day) - exercise energy expenditure (kcal/day)) /fat free mass (kg)

Harmful effects have shown to occur with EA less than 30 kcal/kg FFM/day.

How do you calculate fat mass ?

Fat mass (kg) = body fat (%) * body mass (kg)

How do you calculate fat free mass?

Fat free mass (kg) = body mass (kg) - fat mass (kg)

What are risk factors for Osteoporosis (ACCESS)?

Alcohol Use

Corticosteroid Use

Calcium Low

Estrogen Low

Smoking

Sedentary Lifestyle

What is the exercise recommendation for bone health?

Mode: Weight bearing endurance activity such as tennis, stair climber, basketball, volleyball, and resistance exercise

Intensity: moderate to high

Frequency: weight bearing endurance activities 3-5x per week, resistance exercise 2-3x per week

Duration: 30-60 min/day

What are common measurements for all GXTs?

cardiac electrical conduction through 12-lead ECGs, ratings of perceived exertion (RPE), oxygen consumption, and blood pressure.

Why do we perform graded exercise tests?

To evaluate cardiorespiratory fitness, extension of the history and physical, evaluate exertional discomfort, evaluate the presence of hidden coronary artery disease, risk stratification in patients with CVD, and provide an exercise prescription

What is defined as a healthy blood pressure?

120/80 mmHG

A sBP of 130 and dBP of 90 an greater is categorized as high blood pressure

Why is MAP important and how do we calculate it at rest vs. exercise?

MAP is important because it determines the rate of blood flow through vasculature.

This measurement loses accuracy during exercise because the heart is now in systole for a greater amount of time compared to rest.

@ rest: MAP = dBP + 1/3 PP (sBP-dBP)

during exercise: MAP = Q * TPR (sum of resistance to blood flow in vasculature)

What influences blood pressure during exercise?

Cardiac output (Q) and total peripheral resistance (TPR). If these are increase so is blood pressure.

BP will increase during exercise due to a large increase in Q which is due to elevated HR and left ventricular contractility as a result of sympathetic activity. Increase venous return (preload) increase Q by 5x resting value.

Overall we can contribute the increase to an increase systolic pressure while diastolic remains steady.

What effects does aerobic exercise training have on blood pressure, heart rate, and TPR?

Aerobic training deceases resting and submaximal exercise blood pressure. Decreases resting and submaximal heart rate and vascular tone (TPR) is diminished.

When can a GXT be stopped? Is this absolute or relative?

Either at a predetermined point (given percentage of HRmax) or to the point of volitional exhaustion. They are also stopped when specific signs occur, such as chest pain or breathlessness.

Criteria for test termination can either be absolute (always stopped) or relative (subject to discretion). All depends on goals of test and individual being tested.

What are some general indications for stopping a GXT in low risk adults?

- onset of angina or angina like symptoms

- drop in sBP of > 10 mmHg from baseline blood pressure despite increase in workload

- shortness of breath, wheezing, leg cramps

- Failure of heart rate to increase with increased exercise intensity

-Signs of poor perfusion (light headedness, confusion, nausea, etc)

What happens to stroke volume during a graded exercise?

Stroke volume increase and then plateaus at approximately 50% in untrained individuals.

In trained individuals, stroke volume plateaus at much greater intensities and sometimes may not plateau at all in highly trained individuals.

What is an ECG used for?

An ECG is used as an indicator of the hearts ability to function normally during increased myocardial oxygen demand.

Most common myocardial ischemia during a GXT is ST segment depression.

GXT interpretation

Interpreting GXT results can only be done within the context of the test, including characteristics of subject and goals of test.

GXT is more important in defining risk and predicting future problems than in making a specific diagnosis.

GXT interpretation: Normal/Good Prognosis

-achieve > 80% predicted HRR

-SBP increase 5-10 mmHg per MET

-HR recovery = decrease 12 bpm in 1 minute

- 3 min post-exercise SBP = <90% max SBP

- Normal cardiac rhythms

GXT interpretation: Abnormal/Poor Prognosis

- achieve < 80% predicted HRR

- slow increase or sudden decrease in SBP

- SBP > 250 mmHg or increase > 140 mmHg from rest

- DBP increase > 10 mmHg

- Dysrhythmias, ST segment depression/elevation

True or false: A subject must reach VO2max for a GXT test to produce beneficial information about cardiovascular health

False

What pressure should you inflate the cuff to for a healthy individual?

You should inflate it to 200 mmHg. After you have checked their blood pressure once, you only have to go 20 mmHg above there last SBP recording.

At what rate should you release air from the cuff to obtain an accurate blood pressure measurement?

2 - 3 mmHg

What activities effect blood pressure readings?

- cuff to small (increase 10-40 mmHg)

- cuff over clothing (increase or decrease 10-40 mmHg)

- not resting for 3-5 min (increase 10-20 mmHg)

- legs crossed (increase 5-8 mmHg)

- back/feet unsupported (increase 5-15 mmHg)

- patient talking (increase 10-15 mmHg)

- arm above heart level (decrease 4.6 cm or 1.8 in)

- arm below heart level ( increase 4.6 cm or 1.8 in)

When is it safe to stop supervision of subject during GXT?

It is safe to stop supervision when heart rate (<100 bpm) and blood pressure return to resting/ normal conditions. Also, when there are no other abnormal symptoms present such as chest pain or breathlessness etc.

True or false: High blood pressure always results in acute symptoms.

False

What is the difference between endotherms and exotherms?

Endotherms are warm blooded and warm tissues by metabolic heat production while exotherms are cold blooded and thermal conditions outside the body determine body temp.

What is the normal core temp for humans?

Normal core temperature is around 37 degrees Celsius or 98.6 degrees Fahrenheit with some small variations between individuals and due to factors including circadian variation in both males and females and mensural phase in females.

When can hypothermia occur and what are the signs?

Hypothermia (stage 1) can occur at or below a core temp of 35 degrees Celsius.

Signs include: severe shivering, loss of limb movement, blueness in the skin, and confusion.

Core temp below 32 degrees Celsius is deemed a medical emergency. Symptoms include: hallucinations, delirium, and excessive sleepiness

Core temp as low as 24-26 degrees Celsius can cause respiratory/ cardiac to possible occur.

What happens when your core temp increases?

Your sweat rate will increase along with breathing rate and heart rate.

Symptoms: nausea, dizziness, weakness, and fainting may occur

Heat exhaustion and stroke may be observed as temps exceed 40 degrees Celsius and higher.

Death is nearly certain at 45 degrees Celsius.

During exercise, mechanisms of heat loss are dependent on what? How do these factors alter our mechanisms?

Mechanisms of heat transfer are dependent on the external environment.

If the environment is cooler than our body, heat will be lost via radiation, conduction, and convection.

If the environment is warmer we will see heat loss via conduction, convection, and radiation decrease but will increase for heat gain and evaporative heat loss increases (sweat).

What factors effect evaporative heat loss (sweating)?

Humidity and ambient temperature effect evaporative heat loss. As these two factors increase the maximal capacity for evaporative heat loss decreases!

When humidity is 100% and ambient temp is 30 degrees Celsius and above, evaporative heat loss is minimal.

What is the Wet Bulb Globe Temperature (WBGT)? How do we calculate it?

The WBGT is an index that was developed to address whether or not a certain environment was safe or dangerous to exercise in.

WBGT = 0.7 (Tw) + 0.2(Tg) + 0.1(Td)

Tw= temp of wet bulb, influenced by level of humidity

Tg= temp of black globe, measures radiant heat

Td= temp of ambient air, indicated by dry bulb

What happens to heat in our body during metabolism?

During metabolism, we produce heat as a result of breaking down molecules. The heat production that is not lost is stored in body tissues and this will raise body temp.

For example, a cyclist has efficiency of 20%, this indicates that 80% of the energy transformation is lost as heat.

How do you calculate body heat gain during exercise?

Body heat gain during exercise = heat production - heat loss

What is the specific heat in humans and how do you calculate the heat required to raise body temp 1 degree Celsius?

specific heat in humans= 0.83 kcal/kg

Heat required to raise body temp 1 degree celsius (kcal) = 0.83 (kcal/kg) * body mass (kg)

What happens to your body during exercise and heat stress?

Exercise increase sweat rate and heat stress increases sweat loss which can result in dehydration and reductions in plasma volume.

Changes in plasma volume are not synonymous to changes in loss of body water.

Alterations in total body water and the distribution of water between the intravascular, interstitial, and intercellular compartments can cause a decrease in plasma volume.

What are the four primary mechanisms in which body water loss occurs through during exercise?

1. sweat loss

2. metabolic mass loss (MML)

3. respiratory water loss (RWL)

4. urinary water loss (UWL)

Is the assumption that sweat loss is the ONLY mechanism of water loss during exercise correct?

No this is incorrect. MML, RWL, and UWL also play a factor.

Sweat loss is responsible for most water loss and is why it is sometimes used to estimate body mass alone.

Sweat loss= body mass change following exercise

How do you calculate sweat loss?

Sweat loss = total body mass loss - MML - RWL - UWL

What can heat stress due to an individual?

It can elevate heart rate, reduce stroke volume, leads to reductions in plasma and blood volume, and required a dramatic increase in skin blood flow.

What is the difference between acclimatization and acclimation?

Acclimatization refers to adaptations that are a result of changes in natural environment.

Acclimation refers to adaptations resulting from exposure produced in controlled lab setting.

What does acclimatization/ acclimation due to the body?

Increase in plasma volume, earlier onset of sweating, higher sweat rate, reduced salt loss in sweat, reduced skin blood flow, and an increased synthesis of heat shock proteins.

This will all lead to a reduced heart rate and lower core temp during exercise.

How do you calculate total heat produced to increase body temp by given amount?

Total heat (kcal) = heat required to raise body temp 1 degree Celsius (kcal/degree Celsius) * body temp increase (Celsius)

Calculate the time it takes to increase core temp to given amount

Time to increase to given degree Celsius (min) = total heat (kcal) / (LT velocity (kcal/min) * % heat loss)

Calculating sweat rate (only sweat)

Sweat rate (only sweat) (ml/min) = (pre exercise mass (kg) - post exercise mass (kg) )/ duration (min) 1000g/1kg 1ml/1g

Given gross mechanical efficiency, calculate energy transformation lost as heat

Energy lost as heat (decimal) = 1- gross mechanical efficacy (decimal)

Given energy lost as heat, calculate evaporative heat loss

Evaporative heat loss= energy lost as heat * energy lost through evaporation

Given VO2 and evaporative heat loss, calculate sweat rate

Sweat rate (ml/min)= VO2 (kcal/min) evaporative heat loss (decimal) 1ml sweat/ 0.580 kcal

Given gross mechanical efficiency, calculate energy transformation lost as heat

Energy lost as heat (%) = 100% - gross mechanical efficiency (%)

Given energy lost as heat, calculate kcal as heat

Kcal as heat (kcal/min) = VO2 (kcal/min) * energy lost as heat (decimal)

Given kcal as heat, calculate kcal lost to radiation, convection, and conduction (RCC)

Kcal lost to RCC (kcal/min) = kcal as heat (kcal/min) * RCC loss (decimal)

Calculate kcal lost as sweat, given sweat rate

Kcal lost as sweat (kcal/min) = sweat rate (ml/min) * 0.580 kcal/1ml sweat

Calculate total heat produced during duration of exercise bout

Total heat produced (kcal) = (kcal as heat - kcal as RCC - kcal as sweat) * duration (min)

Given total heat and heat required to raise body temp, calculate body temp increase during exercise bout

body temp increase (Celsius) = kcal increase / heat required to raise body temp 1 degree Celsius (kcal/Celsius)

What happens to your body during heat related exercise fatigue?

- High brain temps reduces neuromuscular drive (reduction in motor unit recruitment)

- Accelerated muscle glycogen metabolism and hypoglycemia

- Increased free radical production (damage to muscle contractile protein)

- Cardiovascular instability

What reduces the partial pressure of oxygen at higher altitudes?

The lower barometric pressure reduces the partial pressure of inspired oxygen (PIO2)

What parameters do we need to consider in order to calculate PiO2?

1. barometric pressure (Pb) -> dependent on altitude

2. water vapor pressure (PH2O) in inspired air (47 mmHg) ->independent of altitude

3. percentage of oxygen in the environment (20.93%) -> independent of altitude

How does an acute reduction in PiO2 affect oxygen level in the blood?

Reduced PiO2 leads to a decrease in alveolar partial pressure of oxygen (PAO2), which leads to a reduction in partial pressure of oxygen in arterial blood (PaO2).

What are three parameters in which arterial oxygen (CaO2) content is determined?

1. hemoglobin concentration

2. arterial hemoglobin O2 saturation (SaO2)

3. the amount of oxygen dissolved in plasma (very little compared to O2 bound to hemoglobin)

What happens to VO2 max when exposed to acute altitude?

VO2 max is reduced.

Percent reductions in VO2 max are greater in endurance trained athletes compared to untrained subject!!!

True or false: the decrease in VO2 max increases the relative intensity of any given absolute (submaximal) power output at altitude

True

What happens to heart rate during acute altitude exposure?

Results in an increase in resting heart rate and an elevation in heart rate at any given absolute submaximal power output.

Maximal heart rate is unaltered with acute altitude exposure