IPHY 4650 - Lab Exam 1

exercise physiology

the study of why and how the body responds and adapts to exercise

energy

the capacity to do work

units of energy

J (Joules, 1 cal = 4.186 J)

mechanical work

force times distance (Nm, J, kcal, kpm, kgm) (force applied against an object and the distance the object moves in the director of the force while the force is applied)

power

workrate (work/time, Watts (J/s), kcal/min, kgm/min, kpm/min)

1 W in kpm/min

6

cycle ergometer

stationary cycle that allows accurate measurement of work performed

VO2

rate of oxygen consumption

graded exercise test

test where workrate is changing and is often the independent variable (VO2 often the DV, ex: monitoring WR on changing ergometer versus VO2)

constant workrate exercise test (CWR)

test in which workmate is constant; time is often the IV (VO2 is DV, ex: monitoring HR over 30 min at fixed workmate)

relative physiological performance parameter values

adjusting an absolute value to a common scale (usually body mass)

%VO2max

relative aerobic power

types of work

chemical, cellular (transport), mechanical

absolute physiological parameters

actual measured values with units (300 W, 80 kg, etc.)

relative physiological parameters

values expressed in relation to another value (usually weight, such as 20 mL/kg/min O2 consumption)

absolute exercise intensity

actual measured value with units (100 W, 10 mph)

relative exercise intensity

expressed relative to individual's maximal capacity (%Vo2max = relative aerobic power!!)

steady-state condition

when physiological parameters (such as HR, VO2) become stable for an extended period of time (can be prevented by intensity)

non-steady-state condition

anytime a physiological parameter is systematically changing over time (always occurs at initial transition to a new workmate)

T/F: all constant workrate exercise is steady state

F

metabolism

all energy transformations that occur in the human body: cellular, chemical, mechanical

all energy transformations in the body produce

heat

rate of heat production in the body is proportional to

metabolic rate

2 ways to measure energy expenditure

direct calorimetry (directly measures heat loss), indirect calorimetry (measures O2 consumption) (foodstuff + O2 (indirect) --> heat + + CO2 + H2O (direct))

direct calorimetry

directly measures heat loss (expensive, complicated)

indirect calorimetry

measures O2 consumption (valid ONLY when energy comes from oxidative pathways)

indirect calorimetry is a valid measure of EE only when energy comes from ________ pathways

oxidative

VO2, or oxygen consumption, is directly proportional to __________.

EE (energy expenditure, 1 LO2 = 5 kcal)

gross efficiency

mechanical power over metabolic power

human machine is not 100% efficient b/c energy is lost as _____. efficiency on a cycle ergometer is around 5-27%.

heat

dynamic energy balance equation

rate of energy stores = rate of change of energy intake - rate of change of energy expenditure

3 components of total daily energy expenditure

total daily activity thermogenesis (30%), thermic effect of food (10%), basal metabolic rate (60%)

components of total daily activity thermogenesis

exercise activity thermogenesis + exercise activity thermogenesis

gross efficiency varies with

work rate, cadence, fiber type, contraction type

basal metabolic rate (BMR) is affected by

fat-free mass, age, sex, body fatness, genetics, caloric restriction/starvation, exercise

MET

a unit that represents multiples of resting metabolic rate (1 MET = 3.5 mL/kg/min)

VO2 equation

volume of inspired O2 - volume expired O2 per minute

values that must be measured during open circuit spirometry

Ve, FeO2, FeCO2 (FiO2 and FiCO2 are constant)

STPD correction factor (purpose)

gas volumes need to be standardized to account for differences in environmental conditions (STPD = standard temp, pressure, dry)

catabolic reactions

breakdown, yield energy (downhill)

anabolic reactions

build up molecules, require energy (uphill)

2nd law of thermodynamics

two isolated systems in contact with each other, which differ in any way (temperature, density, pressure), will equalize if given the chance

two ways to measure metabolic rate

direct or indirect calorimetry

in indirect calorimetry, measuring __________ indirectly measures metabolic rate

oxygen consumption

caloric expenditure of exercise

5 kcal/LO2

open circuit spirometry

determines VO2 by subtracting O2e from O2i (ViO2-VeO2, determined with Douglas Bag technique)

Douglas Bag technique

subject breathes through mouthpiece attached to a one-way valve (Daniels valve) that permits entry of atmospheric air on one side, removal of air on another

Ve

volume of expired air

FeO2 and FeCO2 are measured using

PARVO

FiO2

0.2093

FiCO2

0.0003

Vi

inspired minute ventilation (often calculated)

gross mechanical efficiency

the ratio of mechanical power (mechanical WR) to metabolic power (rate of EE required to maintain a specific WR)

energy expenditure is measured via

VO2

basal metabolic rate (BMR)

energy utilized to sustain all cellular, chemical, mechanical work at rest (60-70% TDEE)

thermic effect of food (TEF)

energy cost for digestion of food/absorption of nutrients (10% TDEE)

total daily activity thermogenesis (TDAT)

energy cost of exercise and non-exercise activity thermogenesis (EAT/NEAT, 20-30%)

energy balance occurs when energy intake =

EE (static equation, so not very realistic)

two conditions that must be met during exercise for indirect calorimetry to most accurately reflect metabolic rate

using oxidative metabolic pathways, measuring exact O2 and CO2 production

You collected a 1 minute bag during rest. Before you have a chance to analyze the bag, you realize there is a small hole in the bag. Room air leaked into the bag, but none of the original contents leaked out, so the volume of the bag has become artificially inflated. Would FeCO2 be under or overestimated compared to if there were no leak? Why?

It would be underestimated, as atmospheric FCO2 is much lower than that of FeCO2, so the added atmospheric air would decrease the overall FCO2 of the bag.

You collected a 1 minute bag during rest. Before you have a chance to analyze the bag, you realize there is a small hole in the bag. Room air leaked into the bag, but none of the original contents leaked out, so the volume of the bag has become artificially inflated. Would FeO2 be under or overestimated compared to if there were no leak? Why?

It would be overestimated, as the amount of oxygen in atmospheric air is higher than that in expired air (21% O2 in air, 16% in expired breath).

If an individual were trying to lose weight, would it be more advantageous to have a higher gross efficiency or lower gross efficiency? Why? (2 pts)

You would want a lower gross efficiency, if you're less efficient you burn more calories with the same level of movement.

respiratory exchange ratio (RER) purpose

estimate fuel utilization during steady-state, nonprotein exercise

respiratory exchange ratio (RER) equation

VCO2/VO2

factors determining fuel selection with exercise

intensity, duration, training status, diet

how does training improve oxidative capacity?

crossover shifts right with training; increased fat utilization, mitochondrial density, capillary density, FFA transport and oxidation, glycogen sparing

crossover concept

increasing relative intensity increases carbohydrate contribution (increasing %VO2max increases carb % energy contribution)

as exercise _________ increases, there's an increase in FAT utilization and a decrease in CHO utilization

duration

chronically, consuming a high CHO diet ________ CHO utilization during submaximal exercise (same for FAT)

increases

Acutely, consuming CHO before or during acute exercise increases _____ utilization and decrease ____ utilization.

CHO, FAT

RER can be used to estimate ___________ because carbs and fats produce different amounts of O2 and CO2.

substrate utilization

The crossover point is at appx ____%VO2max for untrained subjects and _____%VO2max for trained subjects.

30, 40-50

At low intensity, the relative contribution of fats is _____, and the absolute amount of total calories is _____. absolute amount of fat oxidation is _____.

high, low, low

at moderate intensity, the relative contribution of fats is _____ and the absolute amount of total calories is _____. absolute amount of fat oxidation is ____.

low, high, high

oxygen consumption represents total EE during ________, _________ exercise.

submaximal, steady-state

as exercise intensity increases, _______ and ______ increase linearly.

VO2, EEtot

You are running on the treadmill at the Rec Center and you overhear someone telling their friend that "you burn more absolute fat (kcal/hr) running at 5mph than you do at 7mph". What conditions would make this statement true?

As you increase speed, you are decreasing the relative (%) contribution of fat, but increasing the absolute contribution of fat. So, for the statement to be true, the metabolic increase (absolute contribution) from 5 to 7 mph would need to be small compared to the decrease in relative contribution.

You are running on the treadmill at the Rec Center and you overhear someone telling their friend that "you burn more absolute fat (kcal/hr) running at 5mph than you do at 7mph". What conditions would make this statement false?

As you increase speed, you are decreasing the relative (%) contribution of fat, but increasing the absolute contribution of fat. So, for the statement to be true, the metabolic increase (absolute contribution) from 5 to 7 mph would need to be larger compared to the decrease in relative contribution.

VO2max

maximal capacity to transport and utilize oxygen during dynamic exercise involving a large muscle mass

Fick equation

VO2 = Q*(a-v)O2

cardiac output equation

HR*SV

Studies provide clear evidence that increasing HR max does/does not increase VO2max in healthy young subjects.

does not

Ways to increase VO2max

increase: CO, arteriorvenous O2 difference

ways to increase CO

increase preload, decrease afterload

ways to increase arteriovenous oxygen difference

increase: muscle blood flow, capillary density, mitochondria

muscle blood flow is increased and afterload is decreased by __.

decreases in sympathetic NS activity to working muscle

factors affecting Vo2max

genetics, sex, training, age

lactate and ventilatory thresholds are useful predictors of _______ performance.

endurance

ventilatory threshold is a ______ of lactate threshold

marker

After training, tract and tvent occur at _____ workrates.

greater (form 50-60% to 65-85%) (threshold is where exponential increase begins)

exercise economy

O2 cost of exercise at a given submaximal speed/power output (poor economy = increased VO2 at given speed)

criteria to identify VO2max

valid if TWO of the following are met:

plateau in O2 consumption despite an increase in workload

RER > 1.15

HR > (maxHR - 10)

RPE > 17

Blood lactate > 8 mmol/L

graph for determining ventilatory threshold

IV: O2 uptake, DV: Ve (sudden increase in Ve/VO2 = tvent)

estimated 10k time

10000m / (speed @ tlact + 5 m/min)

VO2 max is measured via ________ during a maximal graded exercise test

indirect calorimetry

The _________ is the most valid and reproducible assessment of cardiovascular fitness

VO2max test

VO2max is dependent on two physiological factors:

maximal ability of the cardiovascular system to deliver oxygenated blood to working tissues, maximal ability of the working muscles to extract oxygen and produce ATP aerobically

SVmax is increased by

increases in preload (end-diastolic volume), increases cardiac contractility, decrease in afterload on ventricles

criteria for Vo2max testing

must involve large muscle groups, ideally involves specific movements used by the athlete in their event

how do genetics impact Vo2max?

inherited factors affect HRmax, COmax, physical working capacity