Exercise Physiology Lab 1 Exam

Work (general definition)

the transfer of energy

mechanical work--> product of the force applied against an object and the distance the object moves in the direction of the force while the force is applied (W (J) = f x d)

chemical work

involved in ATP biosynthesis

cellular work

involved in active transport

mechanical work

accomplished with muscular contractions

What units can work be measured in

Joules

Newton-meters

kilgram meters

kilopond meters

Kilogram (kgm) vs. kilopond meters (kpm)

kilogram is a unit of mass

kgm synonym for kpm--> kpm is a unit of work

kgm / kpm represents (for quantifying work)

work = force x distance

kgm represents the force exhibited by 1 kg multiplied by 1 m

Power (W)

the rate of work done

power (w)= work (j) / time (sec)

often used to describe the rate of transforming metabolic energy to physical performance (aerobic or anaerobic power)

Various ways power can also be expressed besides watts (w)

kcal per minute

kilogram-meters per minut (kgm*min-1)

kilopond-meters per minute (kpm*min-1)

Energy (J)

the rate of work done

the capacity to do work (J)

humans must tx chemical energy from food to perform work

- also measured in calories

Absolute vs. Relative values

absolute terms are actual measures values, with units (ex: 80kg, 10m, 300 W, 1.0 L/min VO2)

Relative are values that are expressed in relation to another value --> in relation to body mass

(ex: 50kg subject exercising at an absolute rate of O2 consumption of 1 L/min; his relative rate of O2 consumption is 20 mL/kg/min)

Absolute VO2 units vs. Relative VO2 consumption units

absoute: L/min

relative: mL/kg/min

ex: 50kg subject exercising at an absolute rate of O2 consumption of 1 L/min; his relative rate of O2 consumption is 20 mL/kg/min

--> 1.0 L*min / 50kg = .02 L/kg/min

--> .02 L/kg*min (1000mL/1L) = 20 ml/kg/min (relative)

Exercise Intensity (absolute and relative terms)

absolute intensities: 100 W, 100mph, or exercise at an absolute rate of O2 consumption of 1.0L/min

relative exercise intensities are expressed relative to each individuals maximal capabilities

synonymous term for %VO2max

relative aerobic power

Graded Exercise vs. Constant Workrate--> exercise testing

Graded exercise test: the workrate changes during the test and is often the independent variable

(ex on cycle--> 50W, 100W and 150 W for 4 min per stage; on tred--> grade changes ever 2 min)

Constant: workmate remains fixed, time is often the independent variable

(ex: monitoring the HR response in a subject over a 30 min exercise bout at a fixed workmate

Steady state vs. Non-steady State

any time a parameter is systematically changing over time, we refer to this as a non-steady state condition.

Metabolism

reflects all chemical and cellular reactions, as well as mechanical work that occurs in living cells

Catabolic Reactions

those that wild energy (downhill)

anabolic reactions

those that require energy input (uphill)

second law of thermodynamics:

two isolated systems in contact with each other, which differ in any way (temp, density, oressure( will equalize if given the opportunity

how is metabolic rate measured

via direct or indirect calorimetry

direct calorimetry

the measurement of metabolic rate

directly quantifying heat production

device: calorimeter (measures heat in calories)

provides a direct measurement of all head production in the body

indirect calorimetry

energy production must occur through oxidative pathways

rate of O2 consumption is a reflection f energy productions and thus metabolic rate

measure the rate of O2 consumption to determine metabolic rate

Calorie

the head required to raise the temp of 1 gram of water 1 degree Celsius

Aerobic metabolism

(i.e. oxidation) utilizes three diff substrates (carbs, fats, protiens) to produce ATP

which substrate utilizes the most ATP

Carbs> fats> proteins

carbs 5 kcal/LO2

fats 4.7 kcal /L O2

protein 4.5kcal/L O2

Rate of Oxygen Uptake (VO2)

subtract the amount of oxygen expired from the amount of oxygen inspired

(VO2= ViO2-VeO2)

what technique is used to measure the rate of oxygen uptake

douglas bag technique

Vexpired (Ve) is collected and analyzed for the [ ] of fractional expired O2 (FeO2) and Co2 (FeCO2) using gas analysis machines = PARVO

O2 and CO2 fractions in the inspired air are constant and do not need to be measured

Indirect Calorimetry --> Metabolic Rate

*Variables to be MEASURED by the technician:

-Room Temp

-Barometric Pressue

-The volume of expired air (Ve) also called Pulmonary ventilation (L/min)

-the fraction of expired oxygen (FeO2)

-the fraction of expired CO2 (FeCO2)

Indirect Calorimetry --> Metabolic Rate

*Variables always KNOWN (do not change between subjects or trials)

-fraction of inspired oxygen (FiO2= .2093)

-fraction of inspired carbon dioxide (FiCO2= .0003)

why do we use the STPD

the Volume expired is saturated with water vapor and is at an ambient temp and pressure

--> this makes comparisons under diff environmental conditions inappropriate

--> thus, all expired min ventilations collected in douglas bag are corrected to dry gas at STPD

(ACCOUNDS FOR DIFFERENCES IN ENVORONMENTS)

STPD correction factor determination:

gas volumes must be standardized to account for differenced in environmental conditions with influence volume

--> expressing a gas volume in STPD makes it possible to eval and compare VO2 values calculated at altitude, sea level, and @ any temp or humidity

Efficiency

bc heat is released as a product of any metabolic rxn in the body (not 100% efficient), only part of the energy transformed goes toward work

heat lost= energy lost

Gross Mechanical Efficiency (ME) (%)

is the ration of mechanical power (mechanical workrate) to metabolic power (rate of energy expenditure required to maintain this specific mechanical workmate)

-->0 to 30%

Efficiency is dependent on many factors such as:

intensity

exercise modality (running/biking/resistance)

training

contraction type (isometric,concentric, eccentric)

muscle fiber type

Energy Balance occurs when

Energy intake = Energy expenditure

Dynamic energy balance equation:

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

1 MET = ? in VO2 (ml/kg/min)

3.5 ml/kg/min

-->ex: 10.5 ml/kg/min= 3 METS

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

conditions: 1) oxidative pathway (aerobic)

2) steady state

if an individual were trying to lose weight would it be more advantageous to have a lower or higher gross efficiency?

LOWER--> bc bigger energy expenditure (more calories lost)

ME (%) =

mechanical power (w) / metabolic power (J/sec)

ex: (100w) / (500 j/sec) = 20% vs.

(100w)/ (400 j/sec)= 25%

the lower your % the more efficient you are at not losing energy as heat

energy lost as heat = calories lost as heat