Endurance Training

What is the objective of endurance training?

The objective of endurance training is to develop the energy production systems to meet the demands of the event.
What are the energy production systems?

In the human body, food energy is used to manufacture adenosine triphosphate (ATP) the chemical compound that supplies energy for muscular contraction. Since ATP is in very low concentrations in the muscle, and since it decreases only to a minor extent, even in the most intense voluntary contraction, tightly controlled energy pathways exist for the continual regeneration of ATP as muscular contraction continues. For continuous exercise, ATP must be re-synthesised at the same rate as it is utilised.

What types of endurance are there?

The types of endurance are aerobic endurance, anaerobic endurance, speed endurance and strength endurance. A sound basis of aerobic endurance is fundamental for all events.

Work conducted by Paul B Gastin, "Energy system interaction and relative contribution during maximal exercise" Sports Med 2001: 31(10); 725-741, provides estimates of anaerobic and aerobic energy contribution during selected periods of maximal exercise (95% effort).
Duration % Aerobic % Anaerobic
0-10 seconds 6 94
0-15 seconds 12 88
0-20 seconds 18 82
0-30 seconds 27 73
0-45 seconds 37 63
0-60 seconds 45 55
0-75 seconds 51 48
0-90 seconds 56 44
0-120 seconds 63 37
0-180 seconds 73 27
0-240 seconds 79 21
Aerobic Endurance

Aerobic means 'with oxygen'. During aerobic work, the body is working at a level that the demands for oxygen and fuel can be meet by the body's intake. The only waste products formed are carbon dioxide and water. These are removed as sweat and by breathing out.

Aerobic endurance can be sub-divided as follows:

* Short aerobic - 2 minutes to 8 minutes (lactic/aerobic)
* Medium aerobic - 8 minutes to 30 minutes (mainly aerobic)
* Long aerobic - 30 minutes + (aerobic)

Aerobic endurance is developed using continuous and interval running.

* Continuous duration runs to improve maximum oxygen uptake (VO2max)
* Interval training to improve the heart as a muscular pump

Aerobic threshold

The aerobic threshold, point at which anaerobic energy pathways start to operate, is around 65% of maximum heart rate. This is approximately 40 beats lower than the anaerobic threshold.
Anaerobic endurance

Anaerobic means 'without oxygen'. During anaerobic work, involving maximum effort, the body is working so hard that the demands for oxygen and fuel exceed the rate of supply and the muscles have to rely on the stored reserves of fuel. The muscles, being starved of oxygen, take the body into a state known as oxygen debt. The body's stored fuel soon runs out and activity ceases - painfully. This point is often measured as the lactic threshold or anaerobic threshold or onset of blood lactate accumulation (OBLA). Activity will not be resumed until the lactic acid is removed and the oxygen debt repaid. Fortunately, the body can resume limited activity after even only a small proportion of the oxygen debt has been repaid. Since lactic acid is produced, the correct term for this pathway is lactic anaerobic energy pathway.

The alactic anaerobic pathway is the one in which the body is working anaerobically but without the production of lactic acid. This pathway can exist only so long as the fuel actually stored in the muscle lasts, approximately 4 seconds at maximum effort.

Anaerobic endurance can be sub-divided as follows:

* Short anaerobic - less than 25 seconds (mainly alactic)
* Medium anaerobic - 25 seconds to 60 seconds (mainly lactic)
* Long anaerobic - 60 seconds to 120 seconds (lactic +aerobic)

Anaerobic endurance can be developed by using repetition methods of relatively high intensity work with limited recovery.

Anaerobic threshold

The anaerobic threshold, the point at which lactic acid starts to accumulates in the muscles, is considered to be somewhere between 85% and 90% of your maximum heart rate. This is approximately 40 beats higher than the aerobic threshold. Your anaerobic threshold can be determined with anaerobic threshold testing.
Speed endurance

Speed endurance is used to develop the co-ordination of muscle contraction. Repetition methods are used with a high number of sets, low number of repetitions per set and intensity greater than 85% with distances covered from 60% to 120% of racing distance. Competition and time trials can be used in the development of speed endurance.
Strength endurance

Strength endurance is used to develop the athlete's capacity to maintain the quality of their muscles' contractile force. All athletes need to develop a basic level of strength endurance. Examples of activities to develop strength endurance are - circuit training, weight training, hill running, harness running, Fartlek etc.
Effect on the heart

As an endurance athlete, you will develop an athlete's heart which is very different to the non athlete's heart. You will have:

* Bradycardia - Low resting pulse rate of under 50 bpm
* ECG shows ventricular hypertrophy (thickening of the heart muscle wall)
* X-ray reveals an enlarged heart
* Blood tests shows raised muscle enzymes

The above for the average person (non athlete) indicate a probable heart block, hypertension, heart failure, a recent myocardial infarct or cardiomyopathy. Should you need to go into hospital or see your doctor, you should inform them that you are an endurance athlete.