Energy for exercise: an introduction
Physical Education · Key Stage 3 · The School
Two ways to get energy
AEROBIC means "with oxygen" — energy made using the oxygen you breathe in, and it can keep going for a long time at a steady pace. ANAEROBIC means "without oxygen" — energy made very fast for a short, hard effort, without waiting for oxygen to arrive. A gentle jog leans on the first. A sprint leans on the second.
Why a sprint cannot last
Anaerobic energy is made fast, but the fuel runs out quickly and a by-product builds up that makes the muscles feel like they are burning. That is why nobody can sprint flat out for five minutes — the system that makes energy fast is also the one that cannot keep it up for long.
A stitch, explained
A sharp pain under the ribs during exercise, a STITCH, is usually harmless. One common explanation is the tissue that holds your organs in place being pulled about unevenly by jostling movement and breathing. It normally eases if you slow down and breathe more steadily. It is not the same as a real injury.
A 100-METRE SPRINT: over in ten seconds, almost entirely anaerobic. A MARATHON: over two hours, almost entirely aerobic. A FOOTBALL MATCH: a mix — jogging most of the time (aerobic), then sprinting for the ball (anaerobic), over and over. A SINGLE MAXIMUM WEIGHTLIFT: a few seconds, anaerobic. A GENTLE 5KM RUN: mostly aerobic. Longer and steadier leans aerobic; short and maximal leans anaerobic.