In energy systems section we saw three different energy systems. Following figure shows the use of anaerobic and aerobic systems as function of heart rate. Note that the number 65% may vary between people and for the same human over time (more trained will lead to higher anaerobic threshold).

What is anaerobic threshold?

The gateway passage between works based mainly on oxygen supply and work without oxygen.
How can you find your personal anaerobic threshold? I’ll use treadmill in the following explanation.

1. Warm up.
2. Increase speed gradually till you get to ~110% of your usual speed. If you usually run at 10 km/h pace try 11 km/h.
3. After running several (2-3) minutes with the new pace one of the following might happen:
• You are feeling your leg muscles start “burning” (meaning that you body doesn’t get enough energy from aerobic system and started using anaerobic lactic system). This speed is your aerobic threshold.
• You don’t feel anything. Increase speed by ~10% and go back to step 3 (running several minutes with the new speed …).
• You don’t feel your legs, but it’s hard to keep current speed for some reason (maybe you feel like you don’t have enough air). It’s too early for you to make this test. For more information please review weakest link section.