Measurements Of Energy Expenditure Flashcards
Indirect calorimetry
- measures an estimate of energy expenditure through gas exchange
- measures how much Co2 is produced & how much o2 is consumed at both rest and during aerobic exercise
- calculation the gas volumes enables us to find out the main substrate being used (carbs / fats)
- accuracy of the test is reliable - gives precise calculation of the Vo2 max
Lactate sampling
- take a tiny blood sample and hand held device will analyse the blood and indicates how much blood lactate is present
- accurate and objective
- means of measuring exercise intensity, the higher the intensity at which the lactate threshold occurs the fitter the athlete is.
- allows performer to select training zones - measured in HR or Power
- regular lactate testing: comparison to see improvement.
- if the results show lower lactate levels at the same intensity = increased peak power/speed, time to exhaustion, recovery HR and higher lactate threshold.
Vo2 max test
- multi stage fitness test, Harvard step test and the cooper 12 minutes run - gives indications or predictions of the Vo2 max
- sports science laboratory = more valid and reliable results using direct gas analysis
-> increasing intensities on treadmill, cycle ergometer or rowing machine
-> air that is expired is calculated by computer software
-> vo + conc of o2 is compared with the % of o2 that is in the atmospheric air = see how much o2 used in the task.
Respiratory exchange ratio (RER)
RER = ratio of Co2 produced compared to o2 consumed + a measure of exercise intensity
- info on fuel usage during Ex, e.g. fats, carbs + protein (all can be oxidised to produce energy)
- for a certain vol of o2, energy released will depend on the energy source.
- calculating the RER determines which En source is being oxidised + whether the performer is working aerobically or anaerobically.
Procedure: athlete attached to gas analyser on treadmill or cycle ergometer
RER = Co2 expired per minute (VCo2) / o2 consumed per minute (Vo2)
RER - what values of RER show that carbs and fats are the fuel source for that exercise
RER value close to 1 = using carbs
RER value approx 0.7 = fats
RER value greater than 1 = anaerobic respiration, more Co2 being produced than o2 consumed