Aerobic and Anaerobic Capacity of Endurance Athletes

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Coach Barbara writes: When you are new to endurance training your goal is to create an aerobic system capable of functioning for the duration of the race (regardless of pace).

First of all you would need to understand that the body uses two different Energy systems:

  • Aerobic system – with oxygen
  • Anaerobic lactic system – without oxygen

We, Coaches understand the energy system capabilities and limitations to design sequenced training programs. In teaching you to listen to your body during training sessions, adjustments can be made in the sequenced workout with careful understanding of the energy system. Remember that all energy systems turn on at basically the same time; intensive tempo running makes high demands on both the aerobic and anaerobic and, thus, is a sharing system.

When some one asks you, “How much are you training?” they usually want to know how far or how often you train each week. Not very often will you be asked, “How hard are you training?”

Understanding the hardness or intensity of your training is the key to understanding how a progressive, balanced training programme is put together.

Check out the list below and get a better understanding of the systems:

  • Aerobic System (with oxygen): provides energy at a slower rate for long-term exercise (e g Ironman, Marathon etc).
  • it uses oxygen to help provide fuel
  • it enables athletes to recover from tough workouts and helps develop the capacity increase repetitions.
  • does not produce fatigue-producing waste products
  • lower intensity exercises
  • takes longer to overload than the anaerobic systems
  • requires a minimum 20 minutes duration training period
  • workload can be continuous or broken up into interval training
  • Anaerobic Lactic System (without oxygen): generates energy quickly and the by- product of this system is lactic acid (e g sprints, weight training, interval training, training at various speeds)
  • less efficient
  • hastening muscle fatigue
  • high intensity level
  • body must burn carbohydrates stored in muscle
  • lactic acid must be removed — can take up to one hour
  • carbohydrates must be replaced for further activity to occur
  • first ten minutes of active recovery produces greatest reduction in lactic acid
  • provide majority of energy requiring high bursts of speed or resistance lasting up to 10 seconds
  • built by alternating periods of work and rest
  • builds on the aerobic base, and challenges the athlete at the upper level of aerobic capacity

With Aerobic training, you become much more efficient at using fat as an energy source for exercise. This allows muscle and liver glycogen to be used at a slower rate. Comparing to Anaerobic training which improves muscle buffering capacity, permitting higher muscle and blood lactate levels. Although sprint-type exercise is anaerobic by nature, part of the energy used during longer sprint bouts comes from oxidation, so muscle aerobic capacity also can be increased with this type of training.

I have mentioned that the energy systems used for certain sports is determined by the intensity (how hard) and duration (how long) of exercise. However, to train at the right intensity, you will need a way to monitor exercise intensity. One of the best ways to monitor is the heart rate monitor. It is possible to take your heart rate manually by placing your fingers (not thumb) on your wrist (palm side) at the base of the thumb. Count the number of pulses for fifteen seconds and then multiply by four.

Your heart rate ranges from rest at the lowest end to the maximum heart rate at the highest end.

  • Resting heart rate – as you get fitter your RHR will get lower because the heart pumps more blood per beat and therefore doesn't have to beat as fast to pump the same amount of blood as it did before.
  • Maximum heart rate – you can measure your MHR accurately by performing a test on an ergometer in a laboratory. The work output is gradually increased until your heart rate stops rising and you can’t keep up with the increased work load. There are also other methods you can use in general training as detailed in several other articles on our website (Read more on finding out your MHR HERE)

Your heart rate monitor is a tool and should not dictate your training! After determining your resting and maximum heart rates you can now establish “training zones”. Each of the training zones uses different energy systems, different fuel supplies and different muscle fiber types.

Depending on the objective of the training session, your coach would prescribe that the main part of the training session be in a certain zone, or that you shift from zone to zone in a set way. If done correctly, this stresses specific features of that system, resulting in improvement and better performance.

By varying the training zones from day to day you challenge the body to improve as well as allowing your body to recover! (Read more on setting training zones HERE).

Brendon Downey of is an Exercise Physiologist, Level 2 triathlon coach, and coach to Sam Warriner, the 2003 ITU Oceania Champion. Coaching and detailed training programs are available at


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