L3 - measuring Force, Work and Power

Question 1

what is force

Answer 1

resistance to overcome

Question 2

what is work

Answer 2

volume of exercise. is the energy needed to apply a force to move an object a particular distance. = force x distance

Question 3

what is power

Answer 3

rate of which work is done in. work/time (watts)

Question 4

ergometer, types and modes

Answer 4

a device from which work and power can be determined. many types (resistance is applied using gravity, air and friction) and many modes (step, swim, run, cycle)

Question 5

main ergometric issues in ex science.

Answer 5

what are you trying to assess? and
are you doing it appropriately?
Validity (relavent) and accuracy (get the right number)
- does your ergometer measure what you want it to? is your protocol appropiate and is it reliable (reporducable0

Question 6

what is strength

Answer 6

the abiloty to produce force.
= max force that can be produced by a muscle group in a single movement

skeletal msucle generates up to 30 N .cm-2 of muscle.

Question 7

what is strength dependent on. (5)

Answer 7

muscle size, fibre type proportions, fibre orientation, neural activation and metabolic factors.

Question 8

in exercise what is accelerarion often relate to?

Answer 8

gravity, body mass, equipment.

Question 9

is power trainable and how is it often expressed relavent to?

Answer 9

highly. body mass or upper limit attainabke (%peak power output)

Question 10

efficiency

Answer 10

ability to maintain force or repeated contractions. depends on strength, motivation, injury, thermoreg, efficiency…

= work rate / metabolic rate * 100. (can only calculate when can measure power output)

Question 11

air-braked ergometers. example, relation with cadence and pros and cons

Answer 11

e.g. rowing machine and cycle. resistance is usually wind vanes.
resistance and so workrate increase exponentially with cadence.
pros relatively cheap.
cons difficult to calibrate 9rely on physiological calibration and need to know barometric pressure (affect resistance)

Question 12

friction braked ergometers. example, relation with cadence and pros and cons

Answer 12

monark bike. mechanical resistance. as cadence increases so does work rate (linear). should take other internal resistances into account.

pros easy to use, relatively cheap, portable and robust.
cons limited precision of work rate control, reduces reliability.

Question 13

electromagnetically-braked ergometers. example, relation with cadence and pros and cons

Answer 13

Velotron and lode cycle. resistance varies inversely with cadence.

pros: wide power range, fine control of power, allows setting of constant power output, or various patterns. decrease measurement error by increase reliability.

cons can be expensive.

Question 14

treadmill ergometry. pros and cons

Answer 14

usually motorised. - inclined slop or tethered against a load cell.

pros
can be highly specific (runners) encourages central rather than peripheral fatigue.

cons
cost and size
variability in running effciency - less certain in energy e

Question 15

swim ergometry (3 types).

Answer 15

tethered swimming - use load cell or hang weight over pulley. limited specificity and little scope for altering power.

swimming power system
swim along pool towing cable attached to generator. more specific and allows changes in speed to be measured.

swim flume
specific, versatile and precisly controlled. very good for knetic and kinematic analyse.

Question 16

fieldable devices

Answer 16

quantify movement and often couple with physiology (heart rate) .

can give insight re fitness e.g., agility, explosive, endurance.

may be less direct but valueable for a team sport and motivational.