Question

For each measurement of physical fitness A–E, select the most appropriate option from the following list of physiological terms. 

1. Aerobic metabolism. 

2. Anaerobic metabolism. 

3. Slow twitch muscle. 

4. Fast twitch muscle. 

5. Maximal oxygen consumption. 

6. Respiratory quotient.

A. The subject tested measures handgrip strength by gripping as strongly as possible a measuring device which gives a reading proportional to the strength of the handgrip. 

B. The subject runs back and forward across a 20 metre length in time to a series of beeps, one for each traverse; the beeps gradually come closer together and the subject’s score is the number of twenty laps completed before giving up either due to fatigue or lagging behind the beeps. 

C. Small samples of blood are taken from an athlete’s ear lobe during exercise and measured for lactic acid content. 

D. The subject’s ventilation rate (litres per minute) expired carbon dioxide and oxygen levels, heart rate, respiratory exchange ratio and blood lactic acid level are measured each 15 seconds during exercise at an increasing level, reaching exhaustion after about 15 minutes. 

E. The timing for completion of a Marathon is recorded.

Answer 1

A. Option 4 Fast twitch muscle. This is a test of muscle strength as opposed to endurance; it is related to muscle bulk and not skill, so the dominant hand is not always the strongest. 

B. Option 3 Slow twitch muscle. In contrast to the above, this is a test of endurance, a property of the less bulky slow twitch muscles. 

C. Option 2 Anaerobic metabolism. Lactic acid is a marker for anaerobic metabolism; a relatively low value at a high level of performance indicates good fitness. 

D. Option 5 Maximal oxygen consumption. Oxygen consumption is calculated from the difference between inspired (atmospheric) and expired oxygen multiplied by the ventilation rate; it is assumed to be maximal when a plateau is reached around the time of exhaustion; heart rate should be maximal and the respiratory exchange ratio (carbon dioxide output/oxygen uptake) should have risen to above 1.0; lactic acid is usually 5–10 times the resting value. 

E. Option 3 Slow twitch muscle. For most people this is the ultimate test of the slow twitch endurance muscle.