Lecture 1 Common Measurements

Metric system

standard system of measurement used by scientists

expresses mass, length, volume

SI units

standardized units of measurement

mass SI unit

kg

Distance SI unit

meter

Time SI unit

seconds

Force SI Unit

Newton

Work SI unit

J

Energy SI unit

J

Power SI unit

Watt

Work

Work (J)= force (N) x distance (m)

1 kpm=

9.81 J

1 kcal=

4186 J or 4.186 kJ

426.8 kpm

1 J=

0.102 kpm

Power (W)

work (J) / time (s)

Ergometry

measurement of work output

Ergometer

device used to measure work

• bench step

• cycle

• arm

• treadmill

Krough

invented first cycle ergometer

Direct calorimetry

measures energy expenditure via measurement of body heat production

Indirect calorimetry

evaluates energy expenditure by measuring oxygen consumption as an estimate of resting metabolic rate

Direct calorimetry

measurement of heat production as an indication of metabolic rate

Components of open-circuit spirometry

• computer

• mixing chamber (collects expired gas)

• gas analyzers (measures O2 and CO2)

• pneumotach (measures gas volume)

• two-way breathing mask

Metabolic equivalent (MET)

1 MET= resting metabolic rate

energy expenditure of physical activities expressed in terms of multiples of MET unit

Exercise efficiency

ratio of work output to energy input

a more efficient individual uses less energy to perform the same amt of work

Net efficiency

ratio of work output divided by energy expended above rest

net efficiency of cycle ergometry often ranges from 15-27%

Factors that impact efficiency

exercise intensity

speed of movement

muscle fiber type

How exercise intensity impacts efficiency

curvilinear relationship btwn work rate and energy expenditure

therefore, efficiency decreases at high exercise intensities bc of higher energy cost

How speed of movement impacts efficiency

there’s an optimum speed of movement and deviation away from optimum speed reduces efficiency

Muscle fiber type

slow muscle fibers (type 1 ) are more efficient in using ATP compared to fast muscle fibers (type 2)

Running economy

oxygen cost (that is energy expenditure) of running at a specific speed

lower oxygen consumption (VO2) at same speed indicates better running economy

Muscle fiber type (in regards to running economy)

slow muscle fibers are more efficient in using ATP compared to fast (type eight fibers)