Energy Zones Explained!
In practice, you might see the codes En1, En2, En3, Sp1, Sp4, or Rec
next to the workout. But what do these codes mean?
Each of these codes are a shorthand name for a specific energy zone! Any time
that you move, your body needs energy,and any time your body uses energy,
your body uses fuel. Your body has three major fuel sources:
Adenosine Triphosphate:
Glucose:
and Oxygen:
Depending on the intensity and duration of your movement, different fuels will be
used in different combinations. Cheeck out the graphic below to see which
fuels are used and when!
Recovery
Energy Zone 1
Heart Rate 00-50% Max
Oxygen-Aerobic
Energy Zone 2
Energy Zone 3
Heart Rate 51-70% Max
Oxygen/Glucose Aero/Anerobic Mix
Exercise Time: +180-15 min
Sprint One
Heart Rate 71-90% Max
Glucose Anaerobic/Aerobic Mix
14-2 min
As you can see, the borders between energy zones are not clearly defined. There
are many variables that can influence how your body uses energy during exercise;
stroke style, total mass, body mass, aerobic capacity, and gender are just a few!
Some types of exercise will always fall into a narrow energy zone range. The 50m
freestyle will always be anerobic, and the 10k will always be aerobic. However,
through diligent training at a specific heart rate threshold, an athlete can push their
aerobic borders further and further. This is good news; you cannot refuel on
glucose and ATP mid race, but oxygen is all around you!
2 min - 8 sec
Sprint Four
90-100% Max Heart Rate
ATP Anaerobic
1-8 sec