aerobic/anaerobic exercise

• what most likely uses fats as a fuel source?

  low intensity aerobic.
• assess the relative importance of aerobic respiration to a cyclist during a 50 mile cycling race?

  Aerobic respiration:

  is needed for activities that require endurance. cycling for 50 miles would take several hours, so aerobic respiration would be needed for the majority of the race. therefore its very important to the cyclist to maintain a good performance during the race.
• assess the relative importance of anaerobic respiration to a cyclist during a 50 mile cycling race?

  anaerobic respiration:

  happens during vigorous exercise when the body cant supply all the oxygen needed to the muscles. anaerobic respiration would be needed for the high intensity parts of the race e.g. the final sprint or cycling on a steep gradient.

  although its important for speed and power the cyclist should avoid using it too often as this would cause muscle fatigue and could lead to a drop performance the whole race.